@article{ author = {Rostami, Vahid and AfsharFarnia, A.}, title = {The Evaluation of Footing Bearing Capacity Rest on Top of Retaining Wall Reinforced by Geogrid in Saturated and Dry Soil}, abstract ={Reinforced soil is a common technique to improve the soil properties and can be used in design of foundations and retaining earth structures. Reinforced earth structures are embankments which are reinforced with reinforcing elements such as geogrids, steel straps, etc. This study evaluates the strip footing bearing capacity that rest on near the geogrid reinforced retaining walls in saturated and dry sandy soil conditions. The previous researches have indeed studied the effects of many different parameters on the strip footing bearing capacity including the number of reinforcing elements, reinforcement depth, vertical distance of the reinforcing elements, etc. However, the retaining walls behavior in saturated embankment conditions has not so far been studied up to now so the emphasis in this article was to study the effect of saturation condition on the footing bearing capacity near the reinforced walls. For this purpose small scale laboratory model tests were carried out to investigate the behavior of strip footing bearing capacity that rest on near the geogrid reinforced retaining walls. A steel frame model box with inner dimensions of 0.5 m × 0.5 m in plan and 0.5 m in height was used. One side of the test box was made of Plexiglas for observations during the tests. The strip footing was made of a steel plate 0.49 m in length, 0.05 m in width and 0.02 m in thickness. An aluminum plate with thickness of 3mm used as retaining wall model. A two-way geogrid sheet with a tensile strength of 20KN/m was used to reinforce the sand bed. The sand bed prepared by sand raining technique and a water tank placed on top of the frame to saturate the bed and Overall, 90 tests were conducted. To evaluate the effect of geogrid length on strip footing bearing capacity in dry condition, three different lengths (L/B=3, 4, 5) was used. The bearing capacity of the strip footing increases with an increase in the geogrid length. Increasing of geogrids lengths prevents expansion of the failure area and allows for wide distribution of applied loads. Based on the BCR diagrams reveals that in most diagrams, the slope of the first part (i.e. L/B=3 to L/B=4) is larger than the slope of the second part, which indicates that an increase in the length to the L/B=4 level causes a significant change in the strip footing’s bearing capacity. As a result, larger increases do not have significant effects on the strip footing’s bearing capacity. Therefore, in this study, the L/B=4 length ratio was recommended as the optimum ratio considering economic problems. To study the effect of the geogrid depth on the footing bearing capacity in the saturated embankment, the bearing capacity at four different depth ratios of u/B=0.25, u/B=0.5, u/B=0.75, and u/B=1.0 are used and that compared with dry condition. The results are showed that increasing the geogrid depth introduced a descending trend in the bearing capacity of the strip footing, so that the full capacity of the geogrid sheet could not be utilized. One reason for this is that increasing geogrid depth would compress the soil between the footing and the geogrid, leading to large settlements. Considering the conditions of the present study, the depth ratio of u/B=0.25 selected as the optimum ratio.}, Keywords = {strip footing bearing capacity,saturated embankment,reinforced soil,geogrid.,}, volume = {17}, Number = {6}, pages = {1-15}, publisher = {Tarbiat Modares University}, title_fa = {بررسی ظرفیت باربری پی واقع بر بالای دیوار حائل مسلح شده با ژئوگرید در خاکریز خشک و اشباع}, abstract_fa ={استفاده از خاک مسلح در طراحی شالوده ها و سازه های حائل خاکی، روشی است که در سال های اخیر متداول شده است. در واقع دیوارهای حائل خاک مسلح، خاکریزهایی هستند که به وسیله المان های مسلح کننده از قبیل ژئوگرید، تسمه های فولادی و ... مسلح شده-اند. در این مقاله به بررسی ظرفیت باربری یک پی نواری که در مجاورت دیوار حائل مسلح شده با ژئوگرید در شرایط خاکریز اشباع وخشک تحت بار استاتیکی قائم قرار گرفته، پرداخته شده است و تاثیر پارامترهایی از قبیل فاصله پی نواری از لبه دیوار، تعداد ژئوگریدها، طول ژئوگرید و عمق قرار گیری ژئوگرید بر روی آن مورد بررسی قرار گرفته است. با توجه به اینکه در تحقیقات محققین پیشین شرایط اشباع بودن خاکریز درنظر گرفته نشده بود، تاکید این مقاله بر تاثیر شرایط اشباع بر ظرفیت باربری پی نواری که در مجاورت دیوار حائل قرار گرفته می باشد. به منظور انجام آزمایش ها از یک مدل آزمایشگاهی کوچک مقیاس بهره گرفته شده است. نتایج این پژوهش نشان می دهد که بکارگیری خاک مسلح در شرایط خاکریز اشباع و خشک موجب افزایش قابل توجه ظرفیت باربری پی نواری نسبت به شرایط خاک غیر مسلح می گردد.}, keywords_fa = {ظرفیت باربری پی نواری,خاکریز اشباع,خاکریز خشک,خاک مسلح,ژئوگرید,}, url = {http://mcej.modares.ac.ir/article-16-15806-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15806-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Ouhadi, v.r and Amiri, M.}, title = {Using Tailings of NanoClay Production Process in Environmental Geotectonic Projects to Retention Cu Contaminants}, abstract ={Soils contaminated with heavy metals are among the common environmental geotectonic problems all around the globe. Clay is considered as one of the best protective layers for environment to absorb polluters. Considerable SSA, very low permeability and the clays cationic capacity have been good factors to use these materials in geo-environmental projects vastly. It can react with the materials existing in the polluters because of the layered structure and special vast surface so the clay can absorb all or some of the dangerous polluter materials passing through the soil. Each part of the mineral materials constituting the clay, carbonate, organic materials, oxides, amorphous materials or remained phases can play a role in the process retention heavy metals. Carbonates play a special role in the process of the clay and metallic polluters’ interaction. The effect of the soil structure in retention heavy metal has been studied in many researches. In geotechnical environment view the clay mineral montmorillonite is one of the clays used in geo-environmental projects. Among the clay minerals montmorillonite has the highest property absorbing polluters. In the absence of clayey soils, compacted bentonite-enhanced sand mixtures are attracting greater attention as suitable material for contaminant barrier systems. The efficiency of these insulated barriers depends largely on their hydraulic and mechanical behavior. In landfills, as the main function of the liner is to minimize the movement of water out of the waste disposal facility, Landfill should satisfy three performance criteria if it is to perform satisfactorily as a barrier material. It should have low hydraulic conductivity (typically less than 1×10-9 m/s), should have sufficient strength in order to be stable during construction and operation, and it should not be susceptible to excessive shrinkage cracking due to water content changes that usually occur during the lifetime of the landfill. On the other hand, provision of the proper platform for landfills has been a concern of geotectonic and environmental geotectonic researchers in the past three decades. One of the objectives of this research was to introduce a material with suitable environmental geotectonic properties, minimum permeability, and maximum contaminant absorption potential. The process of producing nanoclay particles from bentonite clay with a top-down approach involves omission of some materials in the form of tailings. In related studies, the bentonite clay sample was divided into the following two main parts through physical and chemical processes: nano-montmorillonite (SLB) and process tailings (BLB). In this research, through a series of geotectonic and environmental geotectonic experiments the interaction of nano-montmorillonite interaction (SLB), process tailings (BLB), and bentonite clay samples with heavy metal contaminants was studied and analyzed experimentally. It shall be mentioned that the process of separating bentonite clay sample components was analyzed through microstructural X-ray diffraction (XRD) and specific surface area (SSA) experiments as well as scanning electron microscope (SEM) imaging. The tests conducted in the study were mostly on the basis of ASTM standard and the geo-environmental tests directions issued by McGill University of Canada. The soil carbonate percentage was defined by titration method. The specific surface area (SSA) was determined using the ethylene glycol-monoethyl ether (EGME) method. CEC was determined by the BaCl2 replacement method. The carbonate content of the soil was determined by titration, and the soil pH was measured in 1:10 soil solution.Also the soil pollution retention capacity was measured by titration test and HNO3 in different concentrations was added to the samples. Results of the present research suggest that process tailings (BLB) contain approximately 80% of copper as a heavy metal contaminant at a concentration of 100 cmol/kg-soil. In addition, permeability of the BLB sample and its inflation are approximately 5.2 10-10 m/sec and 70%, respectively.}, Keywords = {BLB,XRD,Heavy Metal,NanoClay,Landfill,.,}, volume = {17}, Number = {6}, pages = {17-28}, publisher = {Tarbiat Modares University}, title_fa = {استفاده از ضایعات فرایند تولید نانورس در پروژه‌های ژئوتکنیک زیست‌محیطی به منظور جذب آلاینده‌ فلز سنگین مس}, abstract_fa ={زمینه و هدف: خاک‌های آلوده به فلزات سنگین یکی از مشکلات متداول ژئوتکنیک زیست‌محیطی در سراسر جهان هستند. از سوی دیگر ایجاد بستری مناسب برای مراکز دفن زباله همواره یکی از مخاطرات پژوهشگران ژئوتکنیک و ژئوتکنیک زیست‌محیطی در سه دهه گذشته بوده است. ارائه ماده‌ای با خصوصیات ژئوتکنیک زیست‌محیطی مناسب با کمترین میزان نفوذپذیری و قابلیت جذب حداکثری آلاینده از اهداف این مقاله است. فرایند تولید نانوذرات رسی از رس‌های بنتونیت با رویکرد بالا به پایین شامل حذف بعضی از مواد به شکل ضایعات است. در پژوهش‌های صورت گرفته از طریق فرایندهای فیزیکی و شیمیایی اجزای نمونه رسی بنتونیت به دو بخش اصلی نانومونت‌موریلونیت (SLB) و ضایعات فرایند (BLB) جداسازی شده است. روش بررسی: در این پژوهش با انجام یک سری آزمایش‌های ژئوتکنیکی و ژئوتکنیک زیست‌محیطی فرایند اندرکنش نانومونت‌موریلونیت (SLB)، ضایعات فرایند (BLB) و نمونه رسی بنتونیت با آلاینده‌های فلز سنگین مورد مطالعه و تجزیه و تحلیل آزمایشگاهی قرار گرفته است. شایان ذکر است روند جداسازی اجزا نمونه رسی بنتونیت از طریق آزمایش‌های ریزساختاری پراش اشعه ایکس (XRD)، تعیین سطح ویژه (SSA) و بررسی تصاویر میکروسکوپ الکترونی پویشی (SEM) مورد آنالیز قرار گرفت. بحث و نتیجه‌گیری: نتایج تحقیق حاضر نشان می‌دهد، ضایعات فرایند (BLB) حدود 80% آلاینده فلز سنگین مس را در غلظت cmol/kg-soil 100 نگهداری می‌کند. همچنین میزان نفوذپذیری نمونه BLB در حدود m/sec 10-10*5.2 و درصد تورم آن 70% است.}, keywords_fa = {آلاینده فلز سنگین,نانورس,مرکز دفن مهندسی,}, url = {http://mcej.modares.ac.ir/article-16-15452-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15452-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Bagheri, S. and Kabiri-Samani, A.R.}, title = {Hydraulic Characteristics of flow over the streamlined weirs}, abstract ={The present study is subjected to analytical, numerical, and experimental simulation of hydraulic characteristics of flow over the streamlined weirs. Numerical simulations were performed using an open source software namely OpenFoam. According to the objectives of the present study, to evaluate the results of numerical modeling, experimental investigation was conducted, studying different models of streamlined weirs, experimentally. The profiles of the experimental models as well as the simulated numerical models were designed based on the Joukowsky transform function. By analyzing the results of different turbulence models including standard k-ε model, realized k-ε model, RNG k-ε model, k-ω SST model and Reynolds stress LRR model, the k-ω SST model was chosen as the most accurate numerical turbulence model for the simulation of flow over the streamlined weirs. The results of the numerical simulations for different flow discharges and different geometrical characteristics, indicated that, increasing the flow discharge and the relative eccentricity in Joukowsky transform function, tends to increase the velocity and consequently decrease the pressure over the weir crest. Therefore, the lowest pressure and the most probable potential of cavitation belongs to the circular-crested weirs with λ = 1 and high flow discharges. Furthermore, the results show that the greatest bed shear stresses and the compressive forces occur at the downstream end of the circular-crested weirs, thus the downstream zone of the circular-crested weirs is responsible to large values of bed erosion. This is partly due to formation of shock waves, reduction of the flow depth and enhanced velocity of flow downstream of the circular-crested weirs. Furthermore, the lowest bed shear stresses occur at the upstream end of the circular-crested weirs. Therefore, potential of sedimentation upstream of the circular-crested weirs increases. Accordingly, by employing streamlined weirs with λ< 1, and an appropriate curvature, unfavorable flow conditions would be improved, leading to a more safe and economic hydraulic structure. The present study is subjected to analytical, numerical, and experimental simulation of hydraulic characteristics of flow over the streamlined weirs. Numerical simulations were performed using an open source software namely OpenFoam. According to the objectives of the present study, to evaluate the results of numerical modeling, experimental investigation was conducted, studying different models of streamlined weirs, experimentally. The profiles of the experimental models as well as the simulated numerical models were designed based on the Joukowsky transform function. By analyzing the results of different turbulence models including standard k-ε model, realized k-ε model, RNG k-ε model, k-ω SST model and Reynolds stress LRR model, the k-ω SST model was chosen as the most accurate numerical turbulence model for the simulation of flow over the streamlined weirs. The results of the numerical simulations for different flow discharges and different geometrical characteristics, indicated that, increasing the flow discharge and the relative eccentricity in Joukowsky transform function, tends to increase the velocity and consequently decrease the pressure over the weir crest. Therefore, the lowest pressure and the most probable potential of cavitation belongs to the circular-crested weirs with λ = 1 and high flow discharges. Furthermore, the results show that the greatest bed shear stresses and the compressive forces occur at the downstream end of the circular-crested weirs, thus the downstream zone of the circular-crested weirs is responsible to large values of bed erosion. This is partly due to formation of shock waves, reduction of the flow depth and enhanced velocity of flow downstream of the circular-crested weirs. Furthermore, the lowest bed shear stresses occur at the upstream end of the circular-crested weirs. Therefore, potential of sedimentation upstream of the circular-crested weirs increases. Accordingly, by employing streamlined weirs with λ< 1, and an appropriate curvature, unfavorable flow conditions would be improved, leading to a more safe and economic hydraulic structure.}, Keywords = {Streamlined weir,Joukowsky transform,OpenFoam software,Velocity profile,Pressure distribution.,}, volume = {17}, Number = {6}, pages = {29-42}, publisher = {Tarbiat Modares University}, title_fa = {بررسی مشخصات هیدرولیکی جریان در سرریزهای خط جریانی}, abstract_fa ={هدف از این تحقیق، مطالعه تحلیلی، عددی و آزمایشگاهی جریان بر روی سرریزهای خط جریانی است. با توجه به اهداف تحقیق و به‏منظور ارزیابی نتایج مدل‏سازی‏های عددی حاصل از نرم‏افزار متن‏باز OpenFoam، مدل‏های آزمایشگاهی سرریزهای خط جریانی بر اساس تابع تبدیل ژوکوفسکی طراحی و در آزمایشگاه مورد مطالعه قرار گرفتند. با بررسی نتایج مدل‏های آشفتگی متفاوت، مدل k-ω SST به‏عنوان بهترین مدل آشفتگی، در شبیه‎سازی جریان عبوری از روی سرریزهای خط جریانی انتخاب شد. نتایج شبیه‏سازی‏های عددی به‏ازای دبی‏های مختلف و خصوصیات هندسی متفاوت، نشان داد که با افزایش دبی جریان و نیز افزایش میزان خروج از مرکزیت نسبی در رابطه ژوکوفسکی، سرعت بر روی تاج سرریز خط جریانی افزایش و به‏تبع آن فشار در این محل کاهش می‏یابد. کم‏ترین فشار در نتیجه بیشترین احتمال وقوع پدیده کاویتاسیون مربوط به سرریز تاج‏دایره‏ای (نوعی سرریز خط جریانی با خروج از مرکزیت واحد) است. همچنین نتایج نشان داد که بیشترین تنش‏های برشی بستر و نیروهای فشاری در پایین‏دست سرریزهای تاج‏دایره‏ای رخ می‏دهند و در مقایسه با سرریزهای خط جریانی، بیشترین امکان فرسایش مربوط به پایین‏دست سرریزهای تاج‏دایره‏ای است. دلیل این امر وقوع امواج ضربه‏ای، کاهش عمق و افزایش سرعت جریان در پایین‏دست سرریزهای تاج‏دایره‏ای می‏باشد. علاوه بر این، کم‏ترین مقادیر تنش‏های برشی بستر در بالادست سازه، مربوط به سرریزهای تاج‏دایره‏ای است و درنتیجه این نوع سرریز نسبت به سایر انواع سرریزهای خط جریانی مستعد رسوب‏گذاری در بالادست خود می‏باشد. لذا براساس نتایج حاصل، بهره‏گیری از سایر انواع سرریزهای خط جریانی با انحنای مناسب، می‏تواند مشکلات رایج در سرریزهای تاج‎دایره‎ای را مرتفع سازد.}, keywords_fa = {سرریز خط جریانی,تبدیل ژوکوفسکی,نرم‌افزار OpenFoam,نیم‌رخ سرعت,توزیع فشار,}, url = {http://mcej.modares.ac.ir/article-16-15811-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15811-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Bahaaddini, Mojtab}, title = {Size effect on the mechanical behavior of intact rock}, abstract ={Determination of the rock mass strength is a challenge for geotechnical engineers. Some part of this problem is related to complex interaction of rock mass components, intact rock and discontinuities, and the other part is related to difficulty in determination of the mechanical properties of intact rock and discontinuities. The common approach to determine the mechanical properties of rocks is undertaking laboratory experiments and extrapolate the insitu properties based on these laboratory experiments. This extrapolation, or in the other word size effect, has been remained as a challenge for practical rock engineers for decades. Size effect studies can be divided into two groups of one dimensional scale effect, in which the diameter of samples is fixed and the length of samples are changed, and three dimensional scale effect, in which the ratio of length to diameter, called slenderness ratio, is fixed and the diameter is changed. Review of previous studies on the effect of slenderness ratio on the strength of intact rock shows that in some studies as the slenderness increases up to specific value, the strength decreases while in other studies the slenderness ratio has no significant effect on the strength. Results of previous studies on the effect of sample diameter on the strength of intact rock are also inconclusive. Some studies show that as the diameter of sample increases, the strength decreases while other studies show the increase of strength up to specific diameter or no scale effect. This paper aims to study both one dimensional and three dimensional size effect on intact rock properties. To this end, around 120 sandstone samples with diameter between 19 to 145 mm and slenderness ratio of 1 to 4 were prepared and uniaxial compression tests were carried out on these samples. Uniaxial compression tests were carried out using MTS 815. Axial and circumferential extensometers were used to measure deformation of samples during experiments. Results of this study show that the increase of diameter up to 50 mm resulted in the increase of uniaxial compressive strength and no scale effect was observed for diameters greater than 50 mm. This trend was observed for all slenderness ratios. No scale effect was observed on the elastic modulus and the Poisson’s ratio. Therefore, the minimum diameter of around 50 mm, which is suggested by ISRM and ASTM standards, is the size that scale has no effect on the results of uniaxial compression tests. It was found that the increase of slenderness ratio up to 2.5 results in the decrease of strength and no significant effect was observed for greater slenderness ratios. To find out the reason of observed behavior, failure mechanisms of samples at different slenderness ratios were studied. Four types of failure mode were observed in the experiments; generation of a single shear plane, multiple shear planes, shear plane with some cracks in the center of specimens and tensile cracks parallel to the loading direction. It was found that at low slenderness ratios, samples are failed by propagation of tensile cracks which results in higher strength compared to the other failure modes. Therefore, the higher strength of samples with slenderness ratio of 1 is related to this failure mechanism.}, Keywords = {Scale effect,Slenderness ratio,Uniaxial compression test,Failure mechanism,Intact rock,}, volume = {17}, Number = {6}, pages = {44-55}, publisher = {Tarbiat Modares University}, title_fa = {بررسی تاثیر ابعاد نمونه بر رفتار مکانیکی سنگ بکر}, abstract_fa ={رایج‌ترین روش برای تعیین خواص مکانیکی سنگ‌ها، انجام آزمایش در مقیاس آزمایشگاهی و تعمیم آن به خواص درجا می‌باشد. اما نحوه تعمیم خواص آزمایشگاهی به خواص درجا یا بعبارت دیگر تاثیر مقیاس، یکی از چالشهای مهندسین ژئوتکنیک می‌باشد. تعدادی از تحقیقات گذشته، حاکی از کاهش مقاومت با افزایش قطر بوده، درحالیکه تعدادی دیگر افزایش مقاومت تا قطری خاص و یا عدم تاثیر مقیاس را گزارش نموده‌اند. در این مقاله، هدف بررسی تاثیر ابعاد نمونه بر رفتار مکانیکی سنگ بکر می‌باشد. برای این منظور، حدود 120 نمونه ماسه سنگ با قطر بین 19 تا 145 میلیمتر و نسبت لاغری بین 1 تا 4 تهیه گردید و این نمونه‌ها تحت بارگذاری تک محوره قرار گرفتند. نتایج آزمایشات نشان داد که با افزایش قطر نمونه تا حدود 50 میلیمتر، مقاومت فشاری تک محوره افزایش و پس از آن، قطر نمونه تاثیر قابل ملاحظه‌ای بر مقاومت ندارد. همچنین مشخص گردید که قطر نمونه تاثیر چشم‌گیری بر مدول الاستیسیته و ضریب پواسون ندارد. بنابراین حداقل قطر حدود 50 میلیمتر که توسط استانداردهای ISRM و ASTM برای آزمایش فشاری تک محوره پیشنهاد شده، قطری است که در آن تاثیر مقیاس مشاهده نمی‌گردد. همچنین نتایج بررسی تاثیر نسبت لاغری نشان داد که با افزایش این نسبت تا حدود 5/2، مقاومت کاهش می‌یابد و پس از آن این تاثیر از بین می‌رود. برای بررسی دلیل این رفتار، مکانیزم شکست نمونه‌ها مورد بررسی قرار گرفت و مشخص گردید که در نسبت لاغری کم، مکانیزم شکست گسترش ترکهای کششی قائم می‌باشد که باعث ایجاد بالاترین مقاومت در نمونه‌ها می‌گردد.}, keywords_fa = {تاثیر مقیاس,ضریب لاغری,آزمایش فشاری تک محوره,مکانیزم شکست و سنگ بکر,}, url = {http://mcej.modares.ac.ir/article-16-15808-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15808-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Beheshti-Aval, Seyed Bahram and Mohsenian, V. and Nikpour, N.}, title = {A Study on Seismic Performance of RC Tunnel-Form Building Structures With Irregular Plan}, abstract ={The tunnel-form falls under the category of industrial construction methods which is one of the modern construction methods for building houses. A current tendency in the building industry in many countries around the world with increasing city populations, is toward utilizing the modular construction system for development of multistory residential units. The tunnel-form system is an industrialized construction technique in which structural walls and slabs are cast in situ simultaneously using steel forms composed of vertical and horizontal panels set at right angles.The wall and slab frameworks consist of joining horizontal (table) and vertical parts that are reused on multiple stories of a building without being dismantled. The assembled sections are flown by crane from one story to the next. Once in position the gaps between the tables are filled with fillers. They vary in shape and size. The use of these systems can greatly reduce the time and manual labor involved in setting and striking the formwork. Their advantages are best utilized for mass building construction and also for simple designed structures. The main characteristic of a tunnel-form system are its relatively thinner components, i.e. walls and slabs compared to those of traditional reinforced concrete buildings.Through reduction of the construction time and proper performance during the past earthquakes, this type of building construction is recognized as a suitable method used in mass production projects. Despite its widespread use and different behavior in respect of other systems, in the current building design codes, this system has not been considered as an independent structural system. Unfortunately no special seismic code is published for reinforced concrete wall-slab system with tunnel-form and there is only little information about the seismic behavior of this structural system type in technical and research docs. Therefore based on reasonable numerical results, seismic behavior and performance of structures constructed with this technique considering the effective factors on response is highly noteworthy in a seismic code development process. Due to domination of the natural torsion mode respecting to the natural transverse mode based on eigen value analysis of their structural model, use of this system with an irregular plan by the authority building standards departments like the Building and Housing Research Center of Iran has been declared illegal. However, so far no information on their seismic behaviors and vulnerability reports subjected to past earthquakes are available. Necessitating regularity of tunnel-form constructions in the plan and elevation, despite superior advantages such as high-speed manufacturing process and high quality assurance, several limitations in terms of architectural design requirements are one of the basic problems of using this structural system in urban zones. In this paper, the seismic behavior of the two-tunnel-form structures of 5 and 10 stories with an irregular floor plan which were designed based on current building codes in range of nonlinear behavior, is studied. Indeed, performance levels under the design earthquake using the response history and pushover analysis are specified through excitation in two longitudinal and traversal plan directions simultaneously. The results showed the appropriate seismic performance despite the irregularities. Both structures subjected to the design earthquake are placed in the immediate occupancy performance level. It seems that the provision no. 5 of the regulations issued by the Building and Housing Research Center of Iran pertaining to tunnel form building design and construction that stipulate regularity requirement of the tunnel-form plan , at least, are strict and scrupulous for the studied structures.}, Keywords = {RC tunnel form system,plan irregularity,seismic performance levels,design code,}, volume = {17}, Number = {6}, pages = {57-68}, publisher = {Tarbiat Modares University}, title_fa = {مطالعه‌ای بر عملکرد لرزه‌ای سازه‌های بتن‌آرمه قالب تونلی با پلان نامنظم}, abstract_fa ={به علت غلبه مود پیچشی بر مود انتقالی بر اساس نتایج تحلیل مقادیر ویژه بر روی مدل‌های سازه‌ای قالب تونلی، کاربرد این سیستم با پلان نامنظم توسط متولیان تهیه استانداردها چون مرکز تحقیقات ساختمان و مسکن ایران غیر مجاز اعلام شده و این در حالی است که هیچ اطلاعاتی در خصوص رفتار لرزه‌ای سازه‌های بتنی قالب‌تونلی با پلان نامنظم از زلزله‌های گذشته موجود نیست. ضرورت منظم بودن سازه‌های بتنی قالب‌تونلی در پلان و ارتفاع، علی‌رغم مزایایی چون تسریع روند ساخت و تضمین کیفیت بالاتر، محدودیت‌های زیادی از نظر طراحی معماری بدنبال دارد که از مشکلات اساسی کاربرد این سیستم سازه‌ای در مناطق شهری است. در این مطالعه، رفتار لرزه‌ای سازه‌های قالب‌تونلی5 و10 طبقه با پلان نامنظم که بر اساس آیین‌نامه‌های موجود طراحی شده‌اند در محدوده تغییرشکل‌های غیرخطی مورد بررسی قرار گرفته و سطح عملکرد این سازه‌ها، در سطح خطر طرحی آیین‌نامه ایران، با استفاده از تحلیل‌های تاریخچه زمانی و بار‌افزون و با تحریک مدل‌ها در دو راستای طولی و عرضی پلان به صورت همزمان، تعیین شده است. نتایج حاکی از عملکرد لرزه‌ای مناسب این سازه‌ها علی‌رغم وجود نامنظمی در آنهاست. هر دو سازه در زلزله طرح در سطح عملکردی قابلیت استفاده بی‌وقفه قرار گرفتند. به نظر می‌رسد که بند پنجم از ضوابط ابلاغی از سوی مرکز تحقیقات ساختمان و مسکن ایران در خصوص طرح و اجرای سازه‌های قالب‌تونلی که بر منظم بودن در پلان تاکید می‌کند، حداقل برای سازه‌های مورد مطالعه سختگیرانه است.}, keywords_fa = {سازه‌های بتنی قالب تونلی,نامنظمی در پلان,سطوح عملکرد لرزه‌ای,آیین‌نامه طراحی,}, url = {http://mcej.modares.ac.ir/article-16-14741-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-14741-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Biglari, Mahnoosh and Ashayeri, Iman and Hoshyar, Yadegar}, title = {Evaluating inversion of microtremor H/V spectrum in extracting shear wave velocity profile with Down-Hole test results}, abstract ={The velocity of shear wave, which is utilized in evaluation of the stiffness and strength of subsurface layers, the geotechnical site effects of earthquakes, and determination of the profile of subsurface layers is one of the most prominent and essential parameters in geotechnical studies. The profile of shear wave velocity of soil layer is usually discerned in the site by means of prevalent direct seismic and geophysical methods such as reflection, refraction like SASW and MASW, and borehole ways or indirectly, by geotechnical methods such as conducting CPT or SPT sounding and employing experimental relations among Vs and CPT or SPT quantities. As far as these methods need to dig boreholes, it is obvious that deploying borehole geophysical methods or geotechnical ones to certify the profile of shear wave velocity is expensive and time-consuming. As an economical and practical alternative, the measurements of microtremors which can be easily implemented on the ground surface at a single station. Firstly, the method registers ambient vibrations; then, the spectral proportion of the average of horizontal components to vertical component of microtremors (H/V) are determined. At the end, shear wave velocity profile of the site are discerned by inversion of the H/V spectrum in a reversal algorithm. The analyses are easily performed by means Dinver program of useful package of Geopsy software. In this study, single station microtremor measurements are done at six points along Kermanshah Urban Railroad project. In order to determine shear wave velocity profile from inversion of H/V spectrum, four shear wave models with 3,5,7,and 10 layers are initially suggested for all mentioned six points. All initial models were similar in parameters like thickness of layers and range of shear wave velocity in each layer, so that final conclusions and interpretations can be made for future studies. The best of achieved shear wave velocity profiles in terms of minimum misfit error of inversion of horizontal to vertical spectral peak are compared with the result of field Vs measurements that were performed by down-hole experiments. The most outstanding point is that, the procedure is utilized to find shear wave velocity profile without considering the results of down-hole tests for thickness and velocity limits. The comparison showed that there are significant compatibility between shear wave velocity profiles achieved by inversion method and the results of field down-hole tests. Generally, this compatibility increases with increasing the number of layers from three to ten layers of initial models. Furthermore, the depth of exploration grows with increasing the number of layers as well as the accuracy of profiles, so the initial model with 10 layers has more consistency with the results of borehole experiments of all six points in relation to other models. However, it is obvious that the time for analyzing initial model with 10 layers is more than other ones and a tradeoff between accuracy and time of analyses must determine the acceptable results. In conclusion, inversion of H/V spectrum method shows the ability to appropriately estimate shear wave velocity profile even in deeper sediments in relation to down-hole tests.}, Keywords = {Shear wave velocity profile,single station seismogram,microtremors,inversion of horizontal to vertical spectrum ratio,}, volume = {17}, Number = {6}, pages = {69-79}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی روش معکوس نسبت طیفی افقی به قائم خردلرزه های محیطی در استخراج نیمرخ سرعت موج برشی ساختگاه با آزمایش درون چاهی سطح به عمق}, abstract_fa ={به منظور استخراج نیمرخ سرعت موج برشی با استفاده از معکوس نسبت طیفی مولفه‌ی افقی به قائم خردلرزه‌ها (H/V)، اندازه‌گیری‌های خردلرزه‌ای به صورت تک ایستگاهی در شش ایستگاه در مسیر قطار شهری کرمانشاه انجام شد. ابتدا داده‌های ثبت شده توسط دستگاه لرزه‌نگار سه مولفه‌ای، با استفاده از نرم‌افزار Geopsy پردازش و فرکانس غالب ساختگاه برآورد گردید. سپس به منظور تعیین نیمرخ سرعت موج برشی از معکوس طیف H/V، از 4 مدل پیشنهادی 3، 5، 7 و 10 لایه برای همه‌ی نقاط مذکور استفاده گردید و در نهایت به منظور بررسی دقت نتایج حاصله، نیمرخهای سرعت موج برشی به دست آمده از روش معکوس طیف H/V با مدلهای مذکور با نتایج آزمایش درون‌چاهی سطح به عمق (Down-hole) مقایسه شده‌اند. نکته قابل توجه این استکه نیمرخهای سرعت موج برشی ساختگاه بدون توجه به نتایج آزمایشهای درون چاهی برای در نظر گرفتن ضخامت و محدوده‌ی سرعت لایه‌های زمین، استخراج شد و در نهایت با نیمرخ سرعت موج برشی حاصل از آن آزمایشها مقایسه گردید. نتایج به دست آمده از تطابق خوبی با نتایج آزمایشهای درون‌چاهی برخورداراست. تشابه نیمرخ‌های استخراج شده با نیمرخ آزمایش درون چاهی سطح به عمق با افزایش تعداد لایه‌های در نظر گرفته شده در مدل تحلیلی افزایش می‌یابد. همچنین عمق نیمرخهای استخراج شده، با افزایش تعداد لایه‌های مدلهای اولیه افزایش می‌یابد و بدین ترتیب روش معکوس طیف H/V، نیمرخ سرعت موج برشی را تا عمق بیشتری نسبت به آزمایش درون چاهی برآورد می‌کند.}, keywords_fa = {نیمرخ سرعت موج برشی,روش تک ایستگاهی,خردلرزه,معکوس طیف افقی به قائم,}, url = {http://mcej.modares.ac.ir/article-16-15809-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15809-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Taghipoor, Mohammad and Kavussi, Amir and Kazemian, Farbod and adresi, mostaf}, title = {Evaluation of brick powder to improve the fatigue behavior of asphalt mixtures.}, abstract ={Acting as a surface which is supposed to tolerate several reloading of heavy axes, pavement shall hold enough resistance against failures. Fatigue phenomenon is one of the most important causes of weakness in road pavement, which is occurred due to reloading of it. Many laboratory researches are carried out with the purpose to enhance fatigue life of asphalt concrete mix, in which researchers have tried to improve quality of asphalt concrete mix against load carrying transportation vehicles. During recent years, additives like polymer, iron powder, hydrated lime, glass wastages, crumb rubber and brick powder are also considered for improving tar and, consequently, asphalt mix properties. Generally, hot-mix asphalt (HMA) mixtures consist of three components: mineral aggregates, asphalt binder and air voids. It is well recognized that mineral fillers play an important role in the properties of mastics and hot-mix asphalt (HMA) mixtures. Better understanding of the effects of fillers on the properties of mastics and HMA mixtures is crucial to good mix design and high performance of HMA mixtures. In this stydy, the effect of brick powder on fatigue parametrs have been investigatedFiller content for mix design should be determined based on the overall performance of HMA mixtures.It has been recognised with growing concern that agricultural and industrial wastes are increasingly produced in large volume. In order to reduce environmental hazards and conserve natural resources, the use of waste materials in highway pavements would be extremely effective in terms of recycling waste materials. The main purpose of this study was to investigate the effects of waste materials as filler on the performance of hot mix asphalt (HMA) mixtures.It is well recognized that mineral fillers play an important role in the properties of mastics and hot-mix asphalt (HMA) mixtures. Better understanding of the effects of fillers on the properties of mastics and HMA mixtures is crucial to good mix design and high performance of HMA mixtures. Laboratory experiments were conducted to investigate the effect of different fillers on properties of mastics and HMA mixtures. The properties of HMA mixtures were investigated by Marshall, indirect tensile stiffness modulus and indirect tensile fatigue tests. The results indicated that WBP mixtures exhibited higher fatigue life and better performance than control mixtures. With the increase of filler content, some properties of HMA improved while others decreased. The effects of filler were exerted on HMA mixtures through the mastic. Fillers with rough particle texture (such as manufactured sand) tend to increase the stiffening effect of the mastics and mixtures. Considering the overall effects of filler on the properties of HMA mixtures, a filler content range would be required in order to ensure the performance of the mixtures. Waste materials can be mainly regarded as the following classifications: (a) industrial wastes such as cellulose waste, slag, bottom ash and fly ash; (b) municipal/household wastes such as incinerator residue, scrap rubber and waste glass; (c) mining wastes such as coalmine refuse and (d) construction and demolition Based on the results, in consequence of increased awareness of environmental issues and natural resources constraints, the studied waste materials can be advantageously utilised in road construction.}, Keywords = {Pavement,Asphalt mixtures,Additive,Brick powder .,}, volume = {17}, Number = {6}, pages = {81-91}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی تأثیر پودر آجر در بهبود رفتار خستگی مخلوط‌ آسفالتی}, abstract_fa ={روسازی راه‌ها به عنوان سطوحی که تحت بارگذاری مکرر و متعدد محورهای سنگین قرار می‌گیرند، باید دارای مقاومت کافی در برابر خرابی‌ها باشند. پدیده خستگی یکی از مهم‌ترین دلایل بروز ضعف در روسازی راه می‌باشد که بر اثر تکرار بارگذاری در آن رخ می‌دهد. تحقیقات آزمایشگاهی فراوانی به منظور افزایش عمر خستگی مخلوط‌های آسفالتی صورت گرفته که در آن‌ها سعی گردیده تا با استفاده از افزودنی‌های مطلوب، بتوان کیفیت مخلوط‌های بتن آسفالتی در برابر بار وسایل نقلیه افزایش داد. در سالیان اخیر استفاده از افزودنی‌ها از جمله پلیمر، پودر آهن، آهک هیدراته، ضایعات شیشه، خرده لاستیک و پودر آجر جهت بهبود خواص قیر و در نتیجه بهبود خواص مخلوط‌های آسفالتی مورد توجه قرار گرفته است. در این مقاله تاثیر استفاده از افزودنی‌ پودر آجر ضایعاتی بر روی پارامترهای خستگی مخلوط‌ آسفالتی مورد ارزیابی قرار گرفته است. نتایج حاصل از این پژوهش بیانگر تأثیر مثبت این افزودنی‌ در بهبود عملکرد خستگی مخلوط‌های آسفالتی می‌باشد.}, keywords_fa = {روسازی,مخلوط‌های بتن آسفالتی,افزودنی,پودر آجر,}, url = {http://mcej.modares.ac.ir/article-16-14345-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-14345-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {SoltaniMohammadi, Masoud and Jafari, Mohamm}, title = {The investigation of pushover lateral force profile characteristics considering record uncertainties}, abstract ={Abstract: In recent years nonlinear static analysis method has been widely used in the field of performance based earthquake engineering. Whereas the capabilities of this method is well recognized, it still has inherent shortcomings. Accordingly, by considering aspects such as nonlinear properties of members, higher modes effect, and the computational cost, the accuracy of the method should be investigated. Although an enormous study have been carried out to improve the pushover analysis, the proposed methods are almost deterministic and cannot directly consider the seismic records uncertainties. Toward this challenge, the present study aims to examine the requirements of inelastic static analysis method through a comparison with incremental dynamic analysis results. The general purpose of the pushover method is to yield the maximum story responses (shear and drift) expected during the earthquake. For this reason, the selection of the dynamic response absolute maxima is discussed and different criteria are investigated; maximum displacement versus corresponding base shear, maximum displacement versus maximum base shear and, finally, maximum base shear versus corresponding displacement. Therefore, using the information obtained from dynamic analysis, the characteristic of the proper lateral forces that can represent the average of the maximum effect of the ensemble of earthquake records and consider the inherent records uncertainties, can be obtained. So, to derive the characteristics of equivalent lateral forces based on the dynamic response of the system, four different lateral force profiles can be considered; (1) F1: lateral forces create the same average story forces as dynamic analysis, (2) F2: the profile and intensity of the lateral forces that produce the average of the maximum story shear induced by seismic record ensemble, (3) D1: the lateral force profile is chosen in a way that it can produce the same maximum story drifts as dynamic analysis, and (4) D2: the forces that their responses best represent the average of the story lateral displacement in dynamic analysis. The comparisons are performed for three levels of the typical small, medium and high-rise buildings denoted as four, twelve and twenty-story shear frames. The mathematical model of the frames are chosen as the smoothly varying differential Bouc–Wen model. Because of the versatility and mathematical tractability of the Bouc-Wen model, by altering different parameters of the model, it can simulate various structural behavior with any degree of nonlinearity. The estimated responses are compared to those resulted from the nonlinear dynamic analysis. The comparison procedure in the validation process is conducted in two levels; structural global level results (base shear and roof displacement) and story level results (the story drift and lateral force profiles). Furthermore, using the considered characteristics of the lateral load profile, the probabilistic capacity curve which has the potential to be used for assessing different parts of the structure for different performance levels is extracted. As we expect from static nonlinear analysis the demand of the stories should reach their maximum. In fact, in the low-rise structure when the roof displacement reach its maximum, all of the stories also lean towards their maximum demands. By increasing the structures height (followed with higher modes effect), the result of classic pushover analysis cannot correctly estimate the demands and it differs from the result of dynamic analysis.}, Keywords = {Bouc-Wen model,stochastic linearization,probabilistic capacity curve,extreme value,}, volume = {17}, Number = {6}, pages = {93-107}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی ویژگی‌های بارگذاری جانبی در تحلیل بارافزون با در نظر گرفتن عدم قطعیت‌های رکورد به رکورد زلزله}, abstract_fa ={با توجه به اینکه در ارزیابی لرزه‌ای سازه‌ها به صورت گسترده‌ای از روش تحلیل بارافزون استفاده می‌گردد، لازم است با بررسی این روش، محدودیت‌ها و دقت نتایج برای انواع سازه‌ها معلوم گردد. در روش‌های بارافزون موجود، عموما مبنای توزیع بار و محاسبه منحنی ظرفیت و عملکرد سازه تعینی است و عدم قطعیت‌های ناشی از مشخصات زلزله اعمالی به سازه، به صورت صریح منظور نمی‌شود. از این رو در این پژوهش ابتدا با استفاده از مدل چرخه‌ای بوک-ون چنددرجه‌آزاد، انواع مقادیر بیشینه جابجایی بام، بیشینه برش پایه و منحنی‌های ظرفیت حاصل از تحلیل‌های استاتیکی و دینامیکی مقایسه شده است. سپس ویژگی‌های یک الگوی بار جانبی مناسب که بتواند با در نظر گرفتن عدم قطعیت‌های رکورد به رکورد در هر شدت ورودی زلزله، تقاضاهای لرزه‌ای مناسب را در سازه‌ها ایجاد نماید، معرفی شده‌اند. علاوه بر این، نحوه رسیدن به منحنی ظرفیت احتمالاتی سازه که در آن بررسی سازه در مقیاس محلی اعضا و کل سازه برای سطوح اطمینان متفاوت امکان‌پذیر باشد، بررسی شده است. در انتها، پاسخ سازه تحت یک الگوی بار جانبی متغیر که دارای ویژگی‌های مذکور بوده و مبتنی بر احتمال مشخصی از پاسخ لرزه‌ای سازه است به دست آمده است. انطباق مناسب نتایج تحلیل استاتیکی و دینامیکی نشان می‌دهد که الگوی بار جانبی دارای ویژگی‌های مورد نظر می‌تواند به خوبی نتایج احتمالاتی تحلیل دینامیکی را پیش‌بینی نماید.}, keywords_fa = {تحلیل بارافزون تطابقی,منحنی ظرفیت احتمالاتی,مدل بوک-ون,}, url = {http://mcej.modares.ac.ir/article-16-14639-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-14639-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Habibi, A.R. and jami, E.}, title = {}, abstract ={}, Keywords = {}, volume = {17}, Number = {6}, pages = {109-119}, publisher = {Tarbiat Modares University}, title_fa = {ارائه‌ی رابطه‌ی بین پارامترهای لرزه‌ای حرکت زمین با تغییرمکان هدف}, abstract_fa ={حداکثر حرکات زمین، مدت تداوم حرکات شدید و محتوای‌ فرکانسی از مهمترین خصوصیات زمین لرزه‌ها است که در خسارت لرزه‌ای تاثیر بسزائی دارد. در روش‌های متعارف به صورت مستقیم و غیر‌ مستقیم از حداکثر شتاب زمین به عنوان یک پارامتر مهم برای طراحی لرزه¬ای استفاده می‌شود. هدف از تحقیق حاضر بررسی رابطه¬ی بین تعدادی از پارامترهای لرزه‌ای جنبش نیرومند زمین با تغییر مکان هدف سازه که یک شاخص مهم در ارزیابی عملکرد لرزه¬ای است، می¬باشد. به این منظور، ابتدا تغییرمکان¬های هدف یک سازه فولادی با سیستم قاب خمشی 9 طبقه تحت 50 زلزله با استفاده از روش طیف ظرفیت تعیین می‌شود. سپس از مفهوم آماری ضریب همبستگی برای پی بردن به رابطه¬ی بین تغییر مکان هدف و پارامترهای لرزه‌ای مربوط به زلزله‌ها، استفاده می‌شود. نتایج بدست آمده نشان می‌دهد که حداکثر شتاب زمین، رابطه‌ی ضعیفتری را نسبت به بقیه پارامترها از خود نشان می‌دهد؛ در حالی که پارامترهای طیفی همبستگی بیشتری دارند.}, keywords_fa = {ضریب همبستگی, تحلیل استاتیکی غیر خطی, پارامترهای لرزه ای, تغییر مکان هدف سازه}, url = {http://mcej.modares.ac.ir/article-16-33442-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-33442-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Heidari, T. and ShahniKaramzadeh, N. and Ahadiyan, J.}, title = {Analysis of Flow Front Characteristics of Convergent and inclined Plane Surface Jet in Stagnant Water Resources}, abstract ={This study presented the results of an experimental study on the dense flow discharging from convergent and inclined plane surface jet in stagnant and deep ambient resources. Development of industrial and commercial activities throughout the world leads to pollution of water resources. For example, The salt water obtaining from desalination process whose density exceeds the one of the ambient water is discharged into the sea by the desalination plants through discharging structures. Therefore, it is essential to study related processes to suitable transfer of effluent into the ambient. With respect to the importance of this matter, extensive studies have been conducted in recent years as physical and numerical modeling on examining and understanding of flow behavior discharging through submerged and surface jets. This study discusses the plunge and impact location under the effect of different variables. The study tests were carried out in a 3.2×0.6×0.9 m3 flume. The Jet fluid obtained from salt dissolution in water was prepared in three concentrations of 5, 15, and 45 g/lit. To show fluid’s moving path, the obtained solution was colored by using a substance with no effect on density changing. The flow rate of the jet fluid in values of 0.042, 0.08 and 0.105 lit/sec was adjusted by using an electromagnetic flow meter with the accuracy of 0.01 lit/sec. The injection of the jet fluid was carried out by using rectangular channels in four convergence angle of 12.5, 25, 45 and 90 degrees and the constant width of 0.06m. Width of the outlet section in all the channels were considered 0.035 m. Discharge channels injected the jet fluid tangent to the surface of the ambient water. Thus, the channels were installed and adjusted on a base at slopes of zero, 0.04 and 0.08 and certain convergence angle. The water depth in the flume was adjusted at a constant value of 0.7m in all experiments. The ambient fluid was settled before injection of the jet fluid. During this time interval, the temperature of the jet fluid and the ambient fluid were measured by a thermometer and their densities were measured by a hydrometer. For each experiment, the moving path of the jet fluid in the receiving ambient was recorded by using a Sony digital camcorder (DSC-WX220) with the frequency of 50 FPS. This camera recorded the images of flow’s section that was placed in front of the flume’s wall and perpendicular to the central vertical plane of the jet flow. The data was obtained by using of images routing process. Based on the results, the 8-percent slope has the longest length of plunge and impact locations. The 8-percent slope provides high initial momentum. Therefore, the flow has further advance in this condition. Slopes of 0 and 4 percent are very close to each other. Although the value of initial momentum exceeds zero in the 4-percent slope, the length of plunge and impact locations in the 4-percent slope are lower than zero slope. The initial momentum is divided into X and Z directions in 4 percent slope, but all initial momentum is in X direction in zero slope. While the longitudinal slope of the discharge channel is fixed, the length of plunge and impact locations reduce with the jet fluid concentration increasing. Density difference and buoyancy force increase with the concentration increasing. Flow becomes denser and it loses its contact with the surface more quickly. Besides that, the length of plunge and impact locations increases with the convergence angle decreasing. The initial momentum and the discharge velocity of jet flow increase with the convergence angle of discharge channel decreasing. Increasing the initial momentum leads to further advance of jet flow. As the ambient has a fixed depth, was seen the location of the plunge point in the range of 1.2 and the location of the impact point depending on the ambient depth. Finally, the ratio of the length of plunge to impact locations for data was within the range of 0.1-0.8.}, Keywords = {Surface jet,Dense jet,Convergence,Plunge location,Impact location,}, volume = {17}, Number = {6}, pages = {121-129}, publisher = {Tarbiat Modares University}, title_fa = {تحلیل خصوصیات جبهه جریان جت سطحی صفحه ای همگرا و شیبدار در منابع آب ساکن}, abstract_fa ={در این مطالعه نتایج بررسی آزمایشگاهی جریان چگال تخلیه شونده از جت‌های سطحی صفحه‌ای همگرا و شیبدار در منابع پذیرنده ساکن و عمیق ارائه گردیده است. در این راستا، خصوصیات جبهه جریان جت تحت تأثیر پارامترهای هندسی و هیدرولیکی مختلف مورد توجه قرار گرفته است. بدین منظور در محیط آزمایشگاه هیدرولیک دانشگاه شهید چمران اهواز، از فلومی با ابعاد 9/0×6/0×2/3 مترمکعب استفاده گردید. سیال جت نیز به صورت محلول آب-نمک رنگی و در غلظت‌های مختلف فراهم گردید. تخلیه سیال جت در سه شیب متفاوت با استفاده از یک کانال مستطیلی با عرض ثابت و چهار زاویه همگرایی انجام گرفت. استخراج داده‌های مربوط به آزمایش‌ها با استفاده از روندیابی تصاویر ثبت شده توسط دوربین ویدئویی دیجیتال انجام گرفت. مطابق نتایج حاصل، موقعیت نقطه شیرجه جریان جت در محدوده 2/1 و موقعیت برخورد آن وابسته به عمق محیط پذیرنده مشاهده گردید. همچنین، نسبت طول موقعیت شیرجه به موقعیت برخورد جریان برای اکثر داده‌ها در محدوده 1/0 تا 8/0 مشاهده گردید}, keywords_fa = {جت سطحی,جت چگال,همگرایی,موقعیت شیرجه,موقعیت برخورد,}, url = {http://mcej.modares.ac.ir/article-16-14616-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-14616-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Khosravi, Mahdi and GhoreishiNajafabadi, Sayed Hossein and Khosravi, Mohammad Hossei}, title = {Development and Investigation of a Simultaneous Dewatering – Excavation Method for Reducing the Settlement in the Vicinity of Construction Pit}, abstract ={Steady population growth resulted in increasing the land prices which lead to construction of deep excavation. Therefore the use of underground spaces is economically acceptable. One of the most important issues in the design of underground spaces and deep foundation pits is the existence of groundwater and how to control it. The influence of groundwater on a structural project can be very extensive and it may affect the structural design, performance and the total cost of the project significantly. Many problems related to ground water have been observed in excavation sites recently. Those problems have made significant delays in construction process and sometimes lead to significant re-design of the entire operation process. Considering the negative influence of groundwater on the reinforcement system, (e.g. nailing and anchoring) as well as the difficulty of excavation process under wet condition, water must be pumped out from the excavation area. The process of ground water discharge from the construction area which results in lowering the ground water level in that area is called dewatering. Dewatering operation may lead to ground settlement in the vicinity of construction pit which may damage the building. Although the damage due to ground settlement may be negligible, the potential consequences, especially in connection with claims of third parties, requires sufficient attention. In recent years, dewatering and lowering groundwater levels along deep foundation pits subway tunnels in urban environments caused some significant ground subsidence. The mechanism of this type of ground subsidence is that due to water drainage from the soil layers, the hydraulic pressure decreases leading to an increase in the density of the soil and therefore, ground settlement. Dewatering can leads to ground subsidence in different ways where some of them are as: a) removing the finer soil particles from the ground during water pumpage due to a poor pumping performance, b) in the case of dewatering by pumping water from the floor of excavation pit, piping and boiling can reduce the soil strength properties, leading to a failure in the soil mass and c) compaction of the compressible soils or crushable sandy soils due to increasing the effective stress. Some methods such as cut off walls and artificial injection can be used to reduce the ground settlement due to dewatering, but these methods are very time consuming and costly. Furthermore, methods such as artificial injection may have low efficiency and cause environmental effects. Therefore providing a new technique for reducing the dewatering induced ground settlement in less time and cost is necessary. The strategy proposed in this study is to apply a step by step dewatering method, by setting pumping from drainage wells, coincides with the excavation process. For this purpose the PLAXIS2D software is employed as a finite element method to model the settlement due to dewatering. This operation could be applied by modeling two deep foundation pits with the same structures and different groundwater conditions. The proposed step by step method was modeled in this software by estimating the excavation time and coinciding it with water pumping. Step by step dewatering method has some advantages such as reducing the amount of settlement behind the wall and asymmetric ground settlement under adjacent foundation, reducing the amount of water pumping out of the ground, decreasing the Mohr-Coulomb full plastic points in the range of geogrids and reducing the time and cost of dewatering.}, Keywords = {PLAXIS2D,Groundwater,Excavation,Dewatering,Ground settlement,}, volume = {17}, Number = {6}, pages = {131-143}, publisher = {Tarbiat Modares University}, title_fa = {ارائه و بررسی روش خشک‌اندازی همزمان با گودبرداری برای کاهش نشست حاشیه گود}, abstract_fa ={پیامدهای آب زیرزمینی بر یک پروژه ساختمانی بسیار گسترده بوده و بر طراحی سازه ای، برنامه اجرایی و هزینه های کلی پروژه تاثیر می‌گذارد. با توجه به اینکه در نواحی آب گرفته، مهاربندی و اجرای سازه های نگهبان دشوار است، آب باید از ناحیه گودبرداری به بیرون پمپاژ شود که به این عمل خشک‌اندازی گفته می‌شود. عملیات خشک اندازی گاهی منجر به نشست زمین در مناطق اطراف کارگاه شده که با وارد شدن خسارت به ساختمانهای موجود نیز ممکن است همراه باشد. بنابراین ارائه راهکاری مناسب که بتواند با صرف هزینه و زمان کمتر مقدار نشست ناشی از خشک‌اندازی را کاهش دهد امری ضروری می‌باشد. راهکار عملی ارائه شده در این پژوهش، استفاده از روش خشک‌اندازی همزمان با گودبرداری بوسیله تنظیم پمپاژ از چاه‌های زهکش می‌باشد. روش مذکور در این پژوهش بر تخمین زمانهای توقف و اجرا و تنظیم مقادیر پمپاژ بر اساس تراز سطح آب مورد انتظار، با استفاده از نرم‌افزار PLAXIS2D استوار است. از نتایج روش خشک‌اندازی همزمان با گودبرداری می‌توان به کاهش حدود 20 و 9 درصدی در نشست ناشی از خشک‌اندازی و نشست کل در طی عملیات گودبرداری و همچنین کاهش حدود 22 درصدی نشست نامتقارن پی مجاور در این پروژه اشاره کرد. از فواید زیست محیطی روش خشک‌اندازی همزمان با گودبرداری نیز می‌توان به کاهش حدود 68 درصدی مقدار آب خروجی از زمین طی مراحل گودبرداری اشاره کرد و نیز کاهش زمان و هزینه عملیات خشک‌اندازی از دیگر مزایای روش مذکور می‌باشد.}, keywords_fa = {آب‌های زیرزمینی,گودبرداری,خشک‌اندازی,نشست زمین,}, url = {http://mcej.modares.ac.ir/article-16-14481-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-14481-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Roushangar, Kiyoumars and Ghasempour, Roghayeh}, title = {Modeling bed-load discharge in sewer pipes with different boundary conditions using Gene Expression Programming (GEP)}, abstract ={Accurate prediction of the sediment load is one of the important issues to water engineering. Due to complexity of sedimentation phenomenon and influence of various parameters on estimation of sediment transport rate, determining the governing equations are difficult, and classical mathematical models are not sufficiently accurate in this regard. In the present study the applicability of Gene-Expression Programming (GEP) for modeling bed load discharge in sewer pipes with different boundary conditions was assessed (i.e. fixed and movable beds). Therefore different input models based on theoretical concepts were defined for each boundary condition. In order to develop the models, under two scenarios, different input combinations were considered, first scenario (Scenario1) which uses only hydraulic characteristics and second scenario (Scenario2) which uses both hydraulic and sediment characteristics as inputs for modeling bedload discharge. The sewer pipes experimental data available in the literature were applied for training and testing the employed GEP. For evaluating the efficiency of the models three statistical indexes which called: Determination Coefficient (DC), Correlation Coefficient (R) and Root Mean Square Errors (RSME) were used. Then the accuracy and capability of several available bed load formulas such as Ackers, Neilsen, May, Mayerle and Laursen were investigated and compared with GEP- best modes in each boundary. Also with considering this point that may there is no information about bed boundary condition and for evaluating the applicability of applied technique for a wide range of data; all data series of sediment transport were combined. Then, for predicting Cv, as the dependent variable, several models of Scenarioa 2 analyzed for the combined data. The obtained results confirmed the efficiency of Gene-Expression Programming method for estimation sediment discharge in sewage pipes, and proved this method superior to the semi- theoretical relationships. According to the results it was found that in scenario 1, for all of the cases, model (IV) with input parameters of Fr and y0/D presented better performance than the others models, however it was observed that Scenario 2, which took advantage of both hydraulic and sediment parameters as inputs for modeling sediment discharge in sewer pipes performed more successful than Scenario1 which used only combinations of hydraulic parameters as input variables for models. Comparison between the results of separate data sets and combined data set revealed that analyzing data sets separately led to more accurate outcome. According to the results from fixed beds, it was found that adding Frm and d50/y as an input parameter increased the accuracy of the models. For both smooth and rough beds, the model with input parameters λs, Frm, Dgr, d50/y presented better results from the RMSE, R, and DC viewpoints (i.e. highest R and DC and lowest RMSE). For movable beds condition in the two cases of separate dunes and continuous loos bedform, the model with input parameters of ys/D, Frm, Wb/y0 showed more accuracy. This model showed the influence of flow depth and width and depth of movable bed in estimating of bedload transport in sewer pipes. For loose beds Frm has dominant role than other parameters.}, Keywords = {Sediment,Gene Expression Programming (GEP),Sewer pipes,fixed and movable bed.,}, volume = {17}, Number = {6}, pages = {145-157}, publisher = {Tarbiat Modares University}, title_fa = {مدل‌سازی دبی بار بستر در لوله های‌ فاضلاب‌رو با شرایط مرزی متفاوت با استفاده از روش برنامه‌ریزی بیان ژن (GEP)}, abstract_fa ={پیش‌بینی دقیق بار رسوبی یکی از مهم‌ترین موضوعات مهندسی آب می‌باشد. به دلیل پیچیدگی پدیده رسوب و تأثیر پارامترهای مختلف در تخمین نرخ انتقال آن، تعیین معادلات حاکم بر آن مشکل بوده و مدل‌های کلاسیک ریاضی نیز در این راستا از دقت کافی برخوردار نیستند. در این مقاله کارایی روش برنامه‌ریزی بیان ژن (GEP) در تخمین دبی بارکف در لوله‌های فاضلاب‌رو با شرایط مرزی متفاوت (یعنی بستر ثابت و بستر متحرک) مورد ارزیابی قرارگرفته است. بدین منظور برای هر شرایط مرزی مدل‌های ورودی مختلفی مبتنی بر مفاهیم تئوریک و تحت دو سناریو بر اساس دبی رسوب فقط تابعی از مشخصات جریان (سناریو1) و دبی رسوب تابعی از هر دو مشخصات جریان و ذرات رسوب (سناریو2) تعریف گردید. سپس دقت و کارایی چندین فرمول انتقال بار بستر موجود مورد بررسی قرار گرفت و با مدل برتر روش GEP در هر شرایط مرزی مقایسه گردید. نتایج حاصله ضمن تائید قابلیت و کارایی روش برنامه‌ریزی بیان ژن در تخمین دبی عبوری از لوله‌های انتقال فاضلاب، برتری این روش را نسبت به روابط نیمه تجربی به اثبات رساند. همچنین مشاهده گردید که مدل‌های تعریف شده تحت سناریو2 نتایج مطلوب تری را نسبت به مدل‌های سناریو1 ارائه می‌دهند.}, keywords_fa = {رسوب,لوله‌های فاضلاب,برنامه‌ریزی بیان ژن,بستر ثابت و متحرک,}, url = {http://mcej.modares.ac.ir/article-16-15807-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15807-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Ghasemzadehmosavinejad, s. Hosein and Shadmani, Ali and Tahmouresi, Behz}, title = {Mechanism of SBR latex effect on mechanical strength, permeability and microstructure of concrete containing asphalt waste}, abstract ={The use of recycled materials in Portland cement concrete (PCC) has become more and more popular in recent years. Most recycled materials applied in PCC are used to replace coarse aggregates, fine aggregate, or act as cementitious additives. When using recycled materials in PCC, it is desirable that the properties of the concrete can also be improved. Plain PCC, while typically having high strength, generally possesses very low post failure toughness, which may cause abrupt failure of structures and short pavement life. Reclaimed or recycled asphalt pavements (RAP) have been routinely used in the construction of pavement granular bases and hot-mix asphalt concrete. RAP is the removed and/or processed asphalt pavement materials containing both aged asphalt and aggregates. The asphalt coated on the surface of the aggregates typically forms a film with a thickness between six to nine microns. The use of RAP in PCC, though seems to be a viable solution to improve the toughness, has received little attention by research communities. Cementitious systems incorporating polymers have received considerable inter- national attention, especially over the last 30 years or so. The reason for this interest can be attributed to the improved engineering properties when compared to the unmodified materials, e.g. tensile/flexural strength, toughness and durability, the latter including resistance to carbonation, chloride penetration, and frost damage. Additionally, these systems may be used as repair materials where a good bond with the existing concrete or steel is required. Many polymer concrete combinations are available. Polymer-modified cement mortar and concrete (PMC): polymer particles in the form of a latex or redispersible powder are added to a fresh cementitious mix which is then cured. The most commonly used latexes are aqueous suspensions of styrene- butadiene-rubber (SBR) and various acrylics (Ac) containing 45±50% polymer solids. In SBR, the ratio of styrene to butadiene governs the properties of the polymer, with 60±65% styrene giving a good balance. Higher styrene contents would improve compressive and tensile strengths but reduce adhesion and raise the minimum film-forming temperature (MFT). In this study, the effect of SBR latex and silica fume on the mechanical strength (compressive, bending, and splitting tensile strength, elasticity modulus, toughness index), permeability (water penetration, rapid chloride penetration (RCPT), electrical specific resistivity) and microstructure of concrete made with recycled asphaltic aggregates to replaced with natural coarse aggregate (33%, 66% and 100% by weight) were studied. Results showed that the adding of latex and silica fume significantly increased mechanical strength and decrease permeability of concrete mixes. quality and microstructure of interfacial transition zone (ITZ) between aggregate- cementitious matrix by use of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy analysis (EDX) was evaluated. SEM images showed that the mixtures containing latex and silica fume had uniform and smooth structure at surface aggregate- cementitious matrix, and also EDX analysis represents reducing the thickness of ITZ and the calcium to silicon ratio. For assessment of latex effect mechanism on compressive strength, three different type of curing on cube mixtures were applied. The results showed that compressive strength of specimens cured at temperatures significantly increased, which indicates of heating- help to formation polymeric membrane in specimens containing latex.}, Keywords = {Mechanical strength,Microstructure,Permeability,SBR latex,Recycled asphaltic concrete,}, volume = {17}, Number = {6}, pages = {159-170}, publisher = {Tarbiat Modares University}, title_fa = {مکانیزم تاثیر لاتکس SBR بر مقاومت مکانیکی، نفوذپذیری و ریزساختار بتن حاوی ضایعات آسفالتی}, abstract_fa ={صنعت راه و ساختمان بزرگ‌ترین مصرف‌کننده و برداشت کننده مواد از زمین و بزرگ‌ترین تولیدکننده ضایعات جامد است. از راه کارهای مناسب جهت کاهش مصرف مصالح معدنی، بازیافت و به‌کارگیری مجدد مواد پسماندی از جمله نخاله ساختمانی و آسفالتی می‌باشد. در این پژوهش اثر لاتکس لاستیکی بوتادین استایرن (SBR) و دوده سیلیسی بر مقاومت مکانیکی (مقاومت فشاری، خمشی، کشش غیر مستقیم، مدول الاستیسیته، شاخص چقرمگی)، نفوذپذیری (نفوذ آب، نفوذ تسریع شده یون کلر، مقاومت ویژه الکتریکی) و ریز ساختار بتن های ساخته شده با سنگدانه های آسفالت بازیافتی جایگزین درشت دانه طبیعی (33 %، %66 و 100% وزنی)، بررسی شد. نتایج نشان داد که افزودن لاتکس و دوده سیلیسی به طور قابل توجهی موجب افزایش مقاومت مکانیکی شده و نفوذپذیری مخلوط های بتنی را به طور محسوسی کاهش می دهد. با استفاده از ریزنگار الکترون پویشی (SEM) و روش تحلیلی طیف سنجی پراش انرژی پرتو ایکس (EDX)، کیفیت و ریزساختار ناحیه انتقال میان سطحی (ITZ) بین ماتریس سیمانی- سنگدانه ارزیابی شد. تصاویر SEM نشان داد که مخلوط های حاوی لاتکس و دوده سیلیسی ساختار یکنواختی را در مرز مشترک ماتریس سیمانی- سنگدانه داشتند و همچنین تحلیل EDX بیانگر، کاهش ضخامت ITZ و نسبت کلسیم به سیلیس بود. جهت ارزیابی مکانیزم تاثیر لاتکس بر مقاومت فشاری، سه روش مختلف عمل آوری بر نمونه های مکعبی اعمال شد. نتایج نشان داد که مقاومت فشاری نمونه های عمل آوری شده در حرارت به طور محسوسی افزایش پیدا کرده که بیانگر کمک حرارت به شکل گیری غشاء پلیمری در نمونه های حاوی لاتکس است.}, keywords_fa = {بتن آسفالت بازیافتی,لاتکس SBR,مقاومت مکانیکی,نفوذپذیری,ریزساختار,}, url = {http://mcej.modares.ac.ir/article-16-20186-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-20186-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {KasehgarMohammadi, Shoaib and Eghbali, Porya and KasehgarMohammadi, Abozar}, title = {The examination of mixing time on the compressive strength of Nano-silica concrete with rice husk pozzolan}, abstract ={Due to the increasing use of concrete and the use of additives in it , research in this direction is very important . Resistance is one of the effective values in the design and control of concrete quality that numerous factors and parameters affect it . Perhaps increasing in concrete mixing time is one of the parameters that are considered less attention and in this research ; the effect of mixing time on compressive strength of Nano - silica concrete with pozzolan rice husk was studied and were compared with concrete without Nano - silica and pozzolan rice husk .Therefore the effect of sulfate to reduce the resistance of this type of concrete was studied and compared . So , a number of pieces of concrete cube with sides of 15 cm contains %1 Nano - silica and 20% pozzolan husk Rice with a time of mixing varies between 10 to 40 minutes , that every 5 minutes , 3 samples of concrete were taken and made in the days 3 , 7 and 28 under the stress test and ultimately the results of mixing different compressive strength by the time was drawn and reported . Rice husk also tested and its components determined and compared with the standard . Nano - silica concrete and concrete pozzolan rice husk and without Nano – silica and pozzolan was also photographed to compare the density of particles , and at the end testing plan was written by Taguchi testing of concrete . The results show that for the most compressive strength of concrete pozzolan Nano comes with rice husk , the right time (optimal) 25 minutes with a Taguchi test results differ by about 9 percent lower than the margin of error is permitted , that at this time the concrete maximum compressive strength shows the maximum compressive strength at 28 days after the concrete 415 kg/cm2 and then does not show significant strength concrete . Pozzolan concrete without silica and rice husk increasing mixing time increases the compressive strength of concrete 375 kg/cm2 in 28 days from the time the concrete mixing process increase the resistance of shows . Ash consumption in the non - crystalline silica , which is 88% of the project , has shown its high pozzolanic activity . Physical and chemical (XRF) examination showed that rice husk ash used in this project within the requirements of ASTM C-618 for pozzolan is located . XRD results show that the consumer is fully amorphous silica from rice husk ash . As the electro - microscopic pictures (sem) is observed in samples without Nano - silica and pozzolan rice husk , the concrete has uneven texture and large crystals are clearly visible which are connected with needle - shaped crystals and large pores are clear in concrete . However , the concrete samples with Nano - silica and rice husk pozzolan , concrete has a more amorphous structure which are homogeneous and integrated together . And the porosity of the concrete is significantly reduced , which increases the resistance of concrete.}, Keywords = {Nano-silica,rice hull pozzolan,mixing time,the compressive strength of concrete,Taguchi experimental design,}, volume = {17}, Number = {6}, pages = {171-181}, publisher = {Tarbiat Modares University}, title_fa = {بررسی اثر زمان اختلاط بر مقاومت فشاری بتن نانوسیلیس حاوی پوزولان پوسته برنج}, abstract_fa ={باتوجه به کاربرد روزافزون بتن وگسترش استفاده ازافزودنی‌هادرآن،انجام تحقیقات دراین راستا ازاهمیت خاصی برخورداراست.مقاومت یکی از کمیت های مؤثردرطرح وکنترل کیفیت بتن می باشدکه عوامل متعددی برآن تأثیر گذار است. افزایش زمان اختلاط بتن شایدیکی ازپارامترهایی باشد که کمترمورد توجه و بررسی قرار گرفته که دراین تحقیق تاثیرزمان اختلاط بر مقاومت فشاری بتن نانو سیلیس همراه با پوزولان پوسته برنج بررسی وبا بتن بدون نانو سیلیس وپوزولان پوسته برنج مقایسه گردید. همچنین تاثیرمحیط سولفاته برکاهش مقاومت این نوع بتن موردبررسی قرار گرفته وبا هم مقایسه شد. بدین منظور تعدادی آزمونه بتنی مکعبی به اضلاع15سانتیمتر حاوی1%نانو سیلیس و20%پوزولان پوسته برنج بازمانهای اختلاط متفاوت بین10تا40 دقیقه ساخته شدندکه هر5 دقیقه،3 نمونه ازبتن گرفته شدودر روزهای3،7و28 تحت تست فشاری قرارگرفته ودر نهایت نتایج مقاومت فشاری برحسب زمان اختلاط ودرسنین مختلف ترسیم وگزارش گردید. همچنین پوسته برنج تحت آزمایشXRD قرارگرفته و ازنمونه ها نیز عکسSEMگرفته شد تا از نظر تراکم ذرات باهم مقایسه شد ودرآخرتوسط نرم افزار تاگوچی طرح آزمایش از بتن نوشته شد. نتایج تحقیق نشان می دهد که برای دستیابی به بیشترین مقاومت فشاری دربتن نانوسیلیس همراه با پوزولان پوسته برنج، زمان مناسب(بهینه) 25دقیقه است که بانتایج آزمایش تاگوچی حدود 9درصد اختلاف دارد که پایین تر از میزان خطای مجاز می باشد.این بتن دارای ساختار آمورف تر وهمگن تری بوده و باکاهش تخلخل مقاومت خوبی در برابر حمله سولفاتها از خود نشان داده است.}, keywords_fa = {نانوسیلیس,پوزولان پوسته برنج,زمان اختلاط,مقاومت فشاری بتن,طرح آزمایش تاگوچی,}, url = {http://mcej.modares.ac.ir/article-16-14420-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-14420-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {mohammadaliha, mohammadreza and Behbahani, hamed and fattahiamirdehi, hamidrez}, title = {Statistical analysis of mode I fracture mechanics of asphalt mixtures at low temperature based on Weibull prediction model}, abstract ={This paper describes an evaluation of low temperature cracking of asphalt pavement and its propagation agents. Low temperature cracking is one of the noticeable deterioration of asphalt pavement in cold climate regions. This work employed a repeatable semi circular bending (SCB) fracture test to evaluate the low temperature fracture resistance of asphalt mixtures, additionally a large number of edge cracked semi circular bend specimens containing 4% and 7% air voids are used and subjected to symmetric three-point bending load at -10 °c to measure fracture toughness. The effect of air voids on pure mode I asphalt fracture are investigated experimentally and Linear Elastic Fracture Mechanics, its assumptions and effective crack tip parameters introduced, which is used in asphalt fracture mechanics. Then fracture toughness as a main parameter of fracture in the asphalt mixtures is calculated and various methods with different specimen types for determining the fracture toughness of asphalt has been viewed and Asshto suggested method has been discussed, which applied to the experimental part of this work. According to the statistical principle, the experimental results were analyzed by Weibull statistical distribution model in order to present the prediction models for each asphalt mixture with different air voids. The two-parameter and the three-parameter Weibull distribution function was applied to air voids data, Thus compared these two functions. Within the statistical analysis, the probability function for brittle fracture suggested by Wallin using a Weibull analysis that have the three parameters, Kmin, m and K0 ,all of which predicted in this study. The analysis of the results also revealed that Weibull distribution model is one of the most appropriate function for disscussing the volumetric properties of asphalt mixtures.Furthermore, a statistical analysis illustrated that Weibull model is also able to predict the statistical parameters for each set of test data, By preliminary data from the tests and also a well- defined Transfer Coefficient from the previous experimental data that the other researchers obtained through their studies, can be predicted the three-parameter and the two-parameter of Weibull statistical model such as Kmin and K0 which have significant role for asphalt fracture mechanics. In addition to the parameters of Weibull distribution, the average fracture toughness or the average stress intensify factor for asphalt specimens can be predicted from this type of the statistical analysis. In conclusion, this paper emphasises on the statistical and the experimental aspect of asphalt fracture mechanics that has investigated Weibull distribution model and the ability of this model to predict the important fracture parameters and the average stress intensify factor from a determined experimental data based on volumetric properties such as air voids. Finally, by investigating the errors for different models that suggested in this paper, indicatin the suitability of this model to predict the actual values of asphalt fracture.}, Keywords = {Mode I Fracture of asphalt,Weibull model,Low temperature Cracking,}, volume = {17}, Number = {6}, pages = {183-193}, publisher = {Tarbiat Modares University}, title_fa = {بررسی آماری چقرمگی شکست مخلوط های آسفالتی در دمای پایین براساس مدل پیش بینی وایبول}, abstract_fa ={ترک های دمای پایین در روسازی آسفالتی یکی از عوامل تخریب و واماندگی راه ها می باشد. لذا بررسی رفتار شکست و مقاومت ترک خوردگی روسازی آسفالتی بسیار مهم ارزیابی می شود. به دلیل ساختار چند جزیی مخلوط های آسفالتی، پراکندگی داده های آزمایشگاهی برای این مواد از سایر مواد همگن و تک فازی بیشتر می باشد و در نتیجه برای بررسی رفتار ترک خوردگی مخلوط های آسفالتی بایستی از تعداد بیشتری از نمونه های آزمایشگاهی و نیز مدل های آماری استفاده نمود.در این پژوهش برای بررسی رفتار شکست مخلوط های آسفالتی تعداد زیادی آزمایش چقرمگی شکست مود I بر روی نمونه های نیم دیسک خمشی آسفالتی در دو فضای خالی 4 و 7 درصد در دمای 10- درجه سیلیسیوس انجام شد. با بررسی نتایج حاصل از آزمایش های چقرمگی شکست و با استفاده از مدل توزیع تجمعی وایبول، به تحلیل آماری و ارائه مدل پیش بینی نمونه های ترک دار در دو فضای خالی آزمایش شده پرداخته شد. نشان داده شد که با استفاده از مدل آماری وایبول دو و سه پارامتری می توان مشخصات شکست مخلوط های آسفالتی با درصد فضای خالی مختلف را تنها با انجام آزمایش شکست بر روی یک نمونه آسفالتی و با فضای خالی مشخص پیش بینی نمود.}, keywords_fa = {چقرمگی شکست,مود کششی بارگذاری,مدل وایبول,ترک های برودتی دمای پایین,مطالعه آزمایشگاهی وتحلیلی,}, url = {http://mcej.modares.ac.ir/article-16-14939-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-14939-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {mohamadi, Mahdieh and Barghian, Majid and Mostofinejad, D}, title = {Alkali effect on the bond-strength of FRP-concrete bond in EBR and EBROG methods}, abstract ={Various researches have been performed regarding the deterioration and behavior of fabrics made from carbon, glass and aramid in different environmental conditions. Carbon fibers reinforced polymer (FRP) are very corrosion resistant. The CFRP laminates are extremely useful in very corrosive atmospheres, such as marine and aggressive chemical atmospheres. They have been advanced over the years because of their high strength, light weight, long-term durability and high resistance to deterioration. The very thin (0.2 - 0.4 mm) laminates are very easy to apply and can be applied in cross directions without any difficulty. Environmental conditions impact on the bond strength of FRP-to-concrete has sparsely been investigated. The sources of CFRP bond deterioration can originate from alkaline attack and thermal expansion. Alkaline attack occurs at the interface of the concrete and a CFRP laminates with the resulting damage to the matrix of the CFRP laminates. Also, alkali aggregate reaction can lead to the destruction of concrete elements. However, studies in this field are not enough and for externally bonded FRP materials, no such long term test results are available yet. Severe corrosion damage can often be prevented by a correct treatment of the structure against chemical influences or aggressive environmental effects. Methods such as the externally bonded reinforcement (EBR), despite of their advantages, have a problem known as the premature debonding of FRP from concrete substrate. In this method the surface of concrete is sanded and cleaned. After the preparation of the surface, the layer of epoxy is applied uniformly on the surface of concrete. Then, FRP is installed on the surface and saturated with epoxy. In other hand, a new strengthen method is the externally bonded reinforced on grooves (EBROG) method that consists of grooves on the surface of concrete. In this method, grooves with a proper length, width and depth are catted on the concrete surface; then the concrete surface and the grooves are cleaned with an air pressure. Later, grooves are filled with an appropriate epoxy. At the end, FRP sheets are installed with a proper epoxy on the concrete surface. In this paper, the effect of environmental conditions, including three alkaline environments with temperatures of 〖 23〗^° C, 〖40〗^° C and 〖60〗^° C, was investigated on the bond strength of FRP-to-concrete. The specimens were strengthened with two methods: EBR and EBROG. Samples were kept in environmental conditions for 3000 hours. Single-shear tests were conducted to evaluate the bond behavior of FRP-to-concrete. Experimental results showed that the specimens strengthened by the EBROG method - in the alkali environment with different conditions - experienced up to 50 % higher than ultimate bond loads compared with the specimens which were strengthened by the EBR method. In the EBR method, the bond failure mode changed from concrete delamination in laboratory condition to epoxy-concrete interface separation in alkali immersion with different temperatures. On the other hand, in the EBROG method environmental conditions had not effect on the mode of failure and more than 90% of specimens experienced FRP rupture. As a whole, the alkali environment caused a sudden drop in the bond strength of FRP-to-concrete substrate.}, Keywords = {EBR,EBROG,alkaline environment,temperature,}, volume = {17}, Number = {6}, pages = {195-204}, publisher = {Tarbiat Modares University}, title_fa = {تاثیر محیط قلیایی بر مقاومت اتصال نمونه‌های بتنی تقویت شده به روش‌های EBR وEBROG}, abstract_fa ={الیاف پلیمری تقویت شده ( FRP) در مقاوم‌سازی سازه‌های بتنی و فولادی، پل‌ها، مخازن و ... به طور گسترده استفاده می‌شوند. وجود محیط‌های مخرب اعم از دمای بالا، محیط قلیایی، اسیدی و ... امری اجتناب ناپذیر است و در برخی موارد خرابی‌های جبران ناپذیری را سبب می‌شوند. تاثیر شرایط محیطی مختلف بر مقاومت اتصال بین بتن و FRP به طور پراکنده مورد بررسی و آزمایش قرار گرفته است. با این وجود مطالعات در این زمینه کافی نمی‌باشد. به همین منظور در این مقاله تاثیر محیط قلیایی در دماهای مختلف بر مقاومت اتصال بتن-FRP بررسی شده است. مراحل کار به 4 قسمت تقسیم می‌شود: 1) ساخت نمونه‌های آزمایشگاهی، 2) آماده‌سازی سطحی به دو روش نصب خارجی سطحی ( EBR) و نصب خارجی سطحی روی شیار ( EBROG)، 3) تقویت نمونه‌ها با الیاف CFRP و قرار دادن آن‌ها در شرایط محیطی، 4) بررسی مقاومت پیوند سطح بتن- FRP بعد از خارج کردن نمونه‌ها از شرایط محیطی. مقاومت فشاری نمونه‌ها در حدود 35 مگاپاسکال و مدت زمان نگهداری نمونه‌ها در شرایط محیطی 3000 ساعت می‌باشد. نتایج نشان می‌دهد که روش EBROG در شرایط محیطی مختلف عملکرد بهتری نسبت به روش EBR دارد و همچنین ظرفیت باربری نهایی نمونه‌های تقویت شده به روش EBROG در حدود 50 درصد بیشتر از ظرفیت باربری نمونه‌های تقویت شده به روش EBR است.}, keywords_fa = {دما,محیط قلیایی,}, url = {http://mcej.modares.ac.ir/article-16-15456-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15456-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Mahmoodzadeh, Davood and Ketabchi, H.}, title = {Feasibility of groundwater resources cooperative management considering the environmental damages using ant colony optimization}, abstract ={In the recent decades, water demand has been increased specially in arid and semi-arid areas, led to the over-exploitation of water resources. Groundwater resources are important sources of water supply for domestic, industrial and agricultural consumption. Nowadays, over-exploitation from groundwater resources has increased the pressure on these sources which causes the major environmental damages. In this study, a cooperative game theory model is used to investigate how the cooperation of groundwater resources consumers influences the environmental damage and the benefit of stakeholders. The used model in the present study is developed for investigation of an optimal control problem including the variables of economic, environmental, agronomic, and hydrologic issues. Ant colony optimization method is used to flexible define and solve the simulation-optimization problem of this study which provides an ability to consider an extensive range of objectives and constraints. The results show that how uncontrolled pumping and over-exploitation in each aquifer affect on the stakeholders of the adjacent aquifers. Furthermore, the impacts on aquatic ecosystems are analyzed and presented as environmental damages. The obtained results demonstrate that in different areas, environmental damages are reduced under the coalition and effective cooperation condition among stakeholders and considering the environmental externalities in comparison with status quo. In the recent decades, water demand has been increased specially in arid and semi-arid areas, led to the over-exploitation of water resources. Groundwater resources are important sources of water supply for domestic, industrial and agricultural consumption. Nowadays, over-exploitation from groundwater resources has increased the pressure on these sources which causes the major environmental damages. In this study, a cooperative game theory model is used to investigate how the cooperation of groundwater resources consumers influences the environmental damage and the benefit of stakeholders. The used model in the present study is developed for investigation of an optimal control problem including the variables of economic, environmental, agronomic, and hydrologic issues. Ant colony optimization method is used to flexible define and solve the simulation-optimization problem of this study which provides an ability to consider an extensive range of objectives and constraints. The results show that how uncontrolled pumping and over-exploitation in each aquifer affect on the stakeholders of the adjacent aquifers. Furthermore, the impacts on aquatic ecosystems are analyzed and presented as environmental damages. The obtained results demonstrate that in different areas, environmental damages are reduced under the coalition and effective cooperation condition among stakeholders and considering the environmental externalities in comparison with status quo. In the recent decades, water demand has been increased specially in arid and semi-arid areas, led to the over-exploitation of water resources. Groundwater resources are important sources of water supply for domestic, industrial and agricultural consumption. Nowadays, over-exploitation from groundwater resources has increased the pressure on these sources which causes the major environmental damages. In this study, a cooperative game theory model is used to investigate how the cooperation of groundwater resources consumers influences the environmental damage and the benefit of stakeholders. The used model in the present study is developed for investigation of an optimal control problem including the variables of economic, environmental, agronomic, and hydrologic issues. Ant colony optimization method is used to flexible define and solve the simulation-optimization problem of this study which provides an ability to consider an extensive range of objectives and constraints. The results show that how uncontrolled pumping and over-exploitation in each aquifer affect on the stakeholders of the adjacent aquifers. Furthermore, the impacts on aquatic ecosystems are analyzed and presented as environmental damages. The obtained results demonstrate that in different areas, environmental damages are reduced under the coalition and effective cooperation condition among stakeholders and considering the environmental externalities in comparison with status quo.}, Keywords = {Groundwater resources management,cooperative approach,simulation-optimization,Environmental externalities,game theory,}, volume = {17}, Number = {6}, pages = {205-220}, publisher = {Tarbiat Modares University}, title_fa = {امکانسنجی مدیریت همکارانه منابع آب زیرزمینی با در نظر گرفتن خسارات محیط‌ زیستی با استفاده از روش بهینه‌سازی جامعه مورچه‌ها}, abstract_fa ={در دهه‌های اخیر تقاضا برای آب بویژه در مناطق خشک و نیمه‌خشک افزایش یافته است و باعث افزایش بهره‌برداری از این منابع شده است. منابع آب‌ ‌زیرزمینی از منابع مهم تأمین آب برای مصارف در بخشهای مختلف از جمله شرب، صنعت و کشاورزی است. امروزه استفاده بیش از حد از منابع آب زیرزمینی، فشارهای وارده بر این منابع را افزایش داده و پیامد‌های محیطزیستی جبران‌ناپذیری را سبب شده است. در این مطالعه از یک مدل نظریه بازی همکارانه جهت بررسی نحوه همکاری میان بهره‌برداران از منابع آب زیرزمینی با هدف مطالعه خسارت محیط‌زیستی و سود ذینفعان استفاده شده است. مدل استفاده شده در این مطالعه برای بررسی یک مسئله کنترل بهینه شامل مباحث اقتصادی، محیط‌زیستی، کشاورزی و متغیرهای هیدرولوژیکی توسعه داده شده است. جهت تعریف و حل مسئله شبیه‌سازی - بهینه‌سازی بصورت منعطف‌تر در این مطالعه، از روش بهینه‌سازی جامعه مورچه‌ها استفاده شده که امکان تمرکز بر گستره متنوع‌تری از اهداف و قیود را فراهم می‌نماید. نتایج نشان می‌دهد که چگونه برداشت‌های بی‌رویه و کنترل نشده در هر آبخوان بر روی سایر ذ‌‌ینفعان از منابع آب‌زیرزمینی که در مجاورت آن آبخوان قرار گرفته‌اند، تأثیر می‌گذارد. همچنین، اثرگذاری بر روی اکوسسیتم‌های آبی نیز مورد بررسی قرار گرفته و نتایج آن به صورت خسارت محیط‌زیستی ارائه شده است. نتایج مطالعه نشان می‌دهد که در حالت تشکیل ائتلاف و همکاری مؤثر میان ذینفعان در نواحی مختلف و در نظر گیری پیامدهای محیط‌زیستی، خسارات محیط‌زیستی نسبت به شرایط وضع موجود کاهش می‌یابد.}, keywords_fa = {مدیریت منابع آب زیرزمینی,رویکرد همکارانه,شبیه‌سازی - بهینه‌سازی,پیامدهای محیط‌زیستی,نظریه بازی,}, url = {http://mcej.modares.ac.ir/article-16-15810-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15810-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Mehdizadeh, M. and Mamdoohi, Amir Rez}, title = {Role of Parental Environmental Norms on Use of Car in Elementary School Trips, a Quantitative Analysis}, abstract ={Reducing the environmental problems caused by transportation in various trip purposes (especially air pollution caused by cars use) in developed countries is of researches priorities. While in developing countries such as Iran, cultural aspects and environmental norms in discussing the use of cars in school trips (due to the complexity of decision making in school trip mode choice) well not identified. So far, in the field of educational trips have been discussed traffic and urban aspects (Strategies to reduce the volume of traffic), student’s health (encouraging children towards walking or cycling), traffic safety, accident prevention and mode use patterns. Also, less attention has been paid to environmental aspects and its quantification in school trips mode choice. Hence, this study analyses relation of parental norms towards environmental factors besides socio-economic factors in using schools trips modes of elementary students especially household private car what has been done in the frame of questionnaire with their parents. A questionnaire was designed and 1078 Questionnaires were distributed among Parents of students from grade one to three in nine elementary schools (including public and private boys and girls schools) in all districts of department of education in January 2014 (Return Rate: 80%) in Rasht. The questionnaire has three parts: socio-economic part, transport modes in school trips and parental norms towards environment and reducing car use. The questionnaire return rate was approximately 80%. After processing data, 735 questionnaires (more than 68% of total) were identified for analyzing and valid modeling. Based on the data achieved from this field questioning, Binary logit model were used to survey effectiveness and relationships of environmental norms components and socio-economic factors in use of household private car in school trips. Descriptive statistical analysis of the results of socio-economic variables (general characteristic of household) shows that 49.5% of observation were parents of boy student, 78.8% of sample were from public schools, 93.3% of fathers and 67.3% of mothers have driving license. Principal Component Analysis (PCA), with Varimax Rotation implied, a three-factor structure “personal norms ”, “Awareness of Consequences” and “Ascription of Responsibility” for parental environmental norms. Results show that parental environmental norms such as personal norms, concerns, feeling guilty about use of car and sense of responsibility towards the environment can play important role in reducing household private car use in escort of children to school. Also, direct and cross elasticity of logit model show that an increase of one percent of personal norms (Parental concerns about the environment and lees using of household private car) decreases the probability of choosing household private car mode to school by 0.86% and increases 0.15% choosing others school trips modes. An increase of one percent of awareness of environmental responsibilities in the utility of other school trip modes decreases 0.38% the probability of choosing household private car in school trips. Thus, such policies applied by the authorities in order to increasing parental awareness and sense of responsibility about importance of environmental issues with programs such as inviting parents to schools or cultural programs in the media can be effective in reducing car use in school trips.}, Keywords = {environmental norms,private car,elementary student,binary logit,questionnaire,}, volume = {17}, Number = {6}, pages = {221-231}, publisher = {Tarbiat Modares University}, title_fa = {یک تحلیل کمی از نقش هنجار زیست‌محیطی بر استفاده از خودرو در سفر دانش‌آموزان دبستانی}, abstract_fa ={کاهش مشکلات زیست‌محیطی ناشی از حمل و نقل در اهداف مختلف سفر nر کشورهای توسعه‌یافته از اولویت‌های پژوهشی به شمار می‌رود. با توجه به پیچیدگی در فرآیند تصمیم‌گیری انتخاب شیوه سفر دانش‌آموزان دبستانی و نقش مهم والدین در این تصمیم، پژوهش حاضر با پرسش از والدین به تحلیل ارتباط بین هنجارهای زیست‌محیطی نها در کنار سایر متغیرهای اقتصادی- اجتماعی در انتخاب شیوه‌ی خودروی شخصی خانوار برای رساندن دانش‌آموزان دبستانی به مدرسه می‌پردازد. به این منظور پرسشنامه‌ای شامل سه بخش کلی اقتصادی- اجتماعی، شیوه‌های حمل و نقلی سفر به مدرسه و هنجارهای والدین نسبت به محیط‌زیست و استفاده از خودروی شخصی طراحی و به تعداد 1078 میان والدین دانش‌آموزان پایه‌های اول تا سوم دبستان در 9 مدرسه پسرانه و دخترانه دولتی و غیردولتی شهر رشت در اسفند ماه سال 1392 توزیع گردید. مدل لوجیت دوتایی برای تبیین اثرگذاری و ارتباط متغیرهای هنجار زیست‌محیطی و متغیرهای اقتصادی- اجتماعی بر استفاده از شیوه‌ی خودروی شخصی خانوار بکار برده شد. نتایج نشان می‌دهد، مولفه‌های هنجاری زیست‌محیطی والدین از قبیل هنجارهای شخصی، دغدغه‌ها، احساس عذاب وجدان نسبت به استفاده از خودرو و احساس مسئولیت نسبت به محیط‌زیست می‌تواند نقش مهمی در کاهش استفاده از خودروی شخصی خانوار در رساندن کودکان به مدارس رشت داشته باشد. از این رو، اعمال سیاست‌هایی از سوی مسئولین در جهت آگاهی‌ دادن نسبت به اهمیت مسائل زیست‌محیطی و افزایش حس مسئولیت در قبال محیط‌زیست با برنامه‌هایی همچون دعوت والدین به مدارس و یا فرهنگ‌سازی در رسانه‌ها می‌تواند در کاهش استفاده از خودروهای شخصی در سفرهای تحصیلی دانش‌آموزان موثر واقع شود.}, keywords_fa = {هنجار زیست‌محیطی,خودروی شخصی,دانش‌آموز دبستانی,لوجیت دوتایی,پرسشنامه,}, url = {http://mcej.modares.ac.ir/article-16-15720-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15720-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Mousavi, Shahram and Nourani, Vahid and Alami, Mohammad Taghi}, title = {Assessment of Chloride Concentration in Groundwater by Conjugation of Artificial Intelligence and Wavelet Transform Coherence Approaches}, abstract ={When groundwater is contaminated, removal of contaminants and the restoration of quality may be slow and sometimes, impractical. It can be harmful for human health, the ecosystem and can result in water shortage. Thus, simulation of contaminant transport can be an important task in hydro-environmental studies and consequently, it is necessary to develop the robust models which can determine the temporal forecast of pollution. For temporal modeling groundwater level and contaminant concentration (GLCC), several computational methods, namely, finite difference method, finite volume method, finite element method and boundary element method have been applied for numerical solution of governing physical-based partial differential equation (PDE). Although the physical-based numerical technique are widely used for temporal and/or spatial modeling of systems, some real-world conditions such as anisotropy and heterogeneity can have meaningful impacts on GLCC and restrict the usefulness of such methods. As a result, these method may be replaced by other techniques. In situation where there is no sufficient field data and output accuracy is preferred over perception of phenomena, a data-driven or black box model can be proper subsided. The uncertainty and complexity of the groundwater process have caused data-driven models such as artificial neural networks (ANNs) and adaptive neuro-fuzzy inference system (ANFIS) are widely used by hydrogeologists. Several studies have been performed to examine the susceptibility of artificial intelligence (AI) models for GFCT modeling. Wavelet transform coherence (WTC) is a technique for examination the localized correlation coefficient and their phase lag between non-stationary time series as a function of both time-frequency spaces. Furthermore, the cross-wavelet power is indicated as high common power of two time series and is found in time-frequency space by cross wavelet transform (XWT). Specifically, XWT investigates the regions in time-frequency space with large common power about a consistent phase relationship, and accordingly suggestion for causality between and time series. On the other hand, the WTC explores the regions in time-frequency apace in which and time series co-vary, but not essentially with high power. So, while analyzing two time series for evaluating both causality and local co-variance, the WTC is more suitable. In order to examine the applicability of the proposed AI-meshless model in real world conditions, the contaminant transport problem in Miandoab plain located in the northwest of Iran was considered as the case study. Miandoab plain, is located in a delta region of Zarrineh and Simineh Rivers. Urmia Lake in north of Miandoab plain, the largest salt-water lake in the Middle East, has been experienced climate change in early 2 decades. The wavelet transform coherence used in this study can be considered as a novel method for spatial clustering of piezometers, for detecting the interaction of aquifers in the plain and relationship between water level of the lake and GLs and CCs of piezometers located near the lake shore witch can present helpful information in GL and CC modeling. The results showed that the efficiency of ANFIS model was more than ANN model up to 30%. Reliability of ANFIS model is more than ANN model in both calibration and verification stages duo to the efficiency of fuzzy concept to overcome the uncertainties of the phenomenon.}, Keywords = {Groundwater,Contaminant Transport,Artificial Intelligence,Wavelet Transform,}, volume = {17}, Number = {6}, pages = {233-244}, publisher = {Tarbiat Modares University}, title_fa = {بررسی کلراید در آب زیرزمینی با استفاده از تلفیق مدل هوش مصنوعی و روش وابستگی تبدیل موجک}, abstract_fa ={در این تحقیق، مدلهای زمانی جریان آب زیرزمینی و انتقال آلودگی با استفاده از تلفیق تکنیکهای هوش مصنوعی و وابستگی تبدیل موجک توسعه داده شده‌است. دشت میاندوآب به عنوان مطالعه موردی برای شبیه‌سازی تراز آب زیرزمینی و غلظت کلراید مورد مطالعه قرار گرفت. به منظور خوشه‌بندی پیزومترهای دشت، وابستگی تبدیل موجک به عنوان تکنیکی برای بررسی وابستگی و تاخیر فاز بین سری‌های زمانی ناایستای تراز آب و غلظت کلراید استفاده شد. همچنین از وابستگی تبدیل موجک به عنوان یک روش جدید برای مشخص کردن ارتباط سفره‌ها و ارتباط بین تراز آب دریاچه و تراز آب پیزومترهای نزدیک ساحل دریاچه که می‌تواند در مدلسازی تراز آب و غلظت کلراید مفید باشد، استفاده گردید. در ادامه سری‌های زمانی تراز آب و غلظت کلراید در 14 پیزومتر مختلف با استفاده شبکه عصبی مصنوعی و سیستم عصبی-فازی تطبیقی برای تخمین تراز آب و غلظت کلراید در یک ماه بعد آموزش و اعتبارسنجی شدند. نتایج نشان داد که کارایی مدل عصبی-فازی تطبیقی تا 13 درصد بیشتر از مدل شبکه عصبی مصنوعی می‌باشد. توانایی مدل عصبی-فازی تطبیقی در هر دو مرحله آموزش و صحت سنجی بدلیل کارایی منطق فازی برای غلبه بر عدم قطعیت پدیده از شبکه عصبی مصنوعی بیشتر بوده‌است.}, keywords_fa = {آبهای زیرزمینی,انتقال آلودگی,هوش مصنوعی,وابستگی تبدیل موجک,}, url = {http://mcej.modares.ac.ir/article-16-14417-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-14417-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Mirabi, Mohammad Hossein and Mansoori, Abbas}, title = {Assessment of Multi-Equation Mathematical Models of Turbulence in Estimation of Hydrodynamic Parameters at Submerged Jet}, abstract ={Three-dimensional submerged jet at a sudden expansion includes chaotic hydrodynamics. At a sudden expansion, secondary flows developed adjacent to the potential core of the jet generate turbulence, and the formed eddies cause energy transfer and dissipation and decline of fluid momentum in the zone of established flow. By utilizing an efficient mathematical model of turbulence, hydrodynamic flow parameters can be predicted with a good accuracy in various locations. This paper studies the three-equation mathematical models of turbulence, namely the Walters and Cokljat (k-kl-ω), and the seven-equation Reynolds Stress mathematical model of turbulence. Comparison between the results of computational fluid dynamics using Ansys Fluent software and experimental results shows that Reynolds Stress model of turbulence predicts the results with a higher accuracy. It can be concluded that this higher accuracy is due to the use of individual transport equations for each component of the stress tensor in the normal conditions of inhomogeneous and anisotropic turbulence. Kinetic energy, very high fluid momentum and pressure fluctuations are among characteristic of a submerged jets at a sudden expansion. How the energy is dissipated by the flow and how the secondary flow structures are generated need an extensive research. In the submerged jets, because secondary flows are developed in the vicinity of jet potential nuclear and eddies are generated in various sizes, the energy is received from the mean flow and will be being dissipated while being transferred. The dissipation process can be observed during the interaction between stress and strain fields of fluid elements (second-order tensor interaction). Formation of eddies with different sizes and decay of them into smaller structures prompt the process of turbulence diffusion. The energy-bearing eddies formed in the vicinity of the jet potential core are displaced by convection terms. After these eddies are displaced, they experience decay and reduction in size (Kolmogorov microscale) and finally disappear. Rotational dynamics around the jet potential core is of a great importance in terms of flow kinetic energy dissipation; it is why the sudden expansion ratio is a number that represents the range of rotation. Therefore, understanding the flow behavior as well as how the resulting energy is generated and dissipated requires the flow parameters to be known. In order to predict the most accurate (closest to reality) values of the hydrodynamic parameters of a submerged jet, it is necessary to utilize an efficient mathematical model. Among the proposed models of turbulence, only the multi-equation Reynolds stress mathematical model has included anisotropy. Based on what have been stated so far, it seems that the existence of discrete transport equations for each component of stress tensor for a fluid and turbulence kinetic energy dissipation as well as comparison with experimental results provide the possibility of acceptable accuracy in predicting the flow hydrodynamic parameters. In this model, the term of turbulence kinetic energy generation from the mean flow, energy dissipation term, and pressure-strain term transferring the turbulence kinetic energy toward different directions of the coordinate axes are among the very important elements of the transport equation.}, Keywords = {Submerged jet,Multi-Equation Mathematical Models of Turbulence,Computational Fluid Dynamics,}, volume = {17}, Number = {6}, pages = {245-258}, publisher = {Tarbiat Modares University}, title_fa = {ارزیابی مدل‌های ریاضی‌ آشفتگی چند معادله‌ای در تخمین پارامترهای هیدرودینامیکی جت مستغرق}, abstract_fa ={جت مستغرق سه بعدی در یک بازشدگی ناگهانی، دارای هیدرودینامیک آشفته‌ایست. در محل بازشدگی ناگهانی، ایجاد جریان‌های ثانویه مجاور هسته پتانسیل جت، تولید آشفتگی نموده و ادی‌های تشکیل شده باعث انتقال و استهلاک انرژی و همچنین کاهش تکانه سیال در ناحیه استقرار یافته جریان می گردند. با بکار گیری مدل‌ ریاضی آشفتگی مناسب و کارآمد، می توان پارامترهای هیدرودینامیکی جریان را در نقاط مختلف، با دقت مطلوب پیش ‌بینی نمود. در این تحقیق، مدل‌ ریاضی آشفتگی سه معادله‌ای والترز و کوکلجات (k-kl-ω) و مدل ریاضی آشفتگی هفت معادله‌ای تنش رینولدز، مورد بررسی قرار گرفته‌اند. مقایسه نتایج تحلیل دینامیک سیالات محاسباتی به روش حجم محدود در نرم افزار Ansys Fluent با نتایج آزمایشگاهی، نشان می‌دهد که مدل آشفتگی تنش رینولدز نتایجی با دقت بالاتر را پیش بینی می‌نماید. می‌توان به این نتیجه رسید که دلیل این دقت در تخمین، بکار گیری معادلات انتقال مجزا برای هر یک از مولفه‌های تانسور تنش، در شرایط طبیعی آشفتگی غیرمتجانس و غیرهمسانگرد است.}, keywords_fa = {جت مستغرق,مدل‌های ریاضی آشفتگی چند معادله‌ای,دینامیک سیالات محاسباتی,}, url = {http://mcej.modares.ac.ir/article-16-17018-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-17018-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {Nosrati, M. and golshani, Aliakbar and Barani, Omid rez}, title = {Numerical modeling of hydraulic fracturing in a poroelastic medium using cohesive elements}, abstract ={From oil and gas engineering point of view, one of the challenges in low permeable or damaged wells is improving the productivity. There are different methods to increase the productivity of low permeable wells and one of the most efficient one is hydraulic fracturing. In this study, two-dimensional modeling of hydraulic fracturing using finite element method and cohesive element approach through traction-separation law has been performed. This approach avoids the singularity in the crack tip and the cohesive zone fits naturally into the conventional finite element method. Hydraulic fracture is assumed to propagate in a poroelastic and permeable medium with a constant injection rate and under quasi-static conditions and the criterion for fracture initiation is quadratic nominal stress criterion. Also as a propagation criterion, Benzeggagh Kenane (BK) approach has been considered. Two types of elements have been implemented in the model which are 4-node bilinear displacement and pore pressure reduced integration and 6-node displacement and pore pressure two- dimensional cohesive element. Cohesive elements have three degrees of freedom that two of them are in X and Y directions and one of them is pore pressure. Mesh size in the near fracture region is small enough to consider the stress and pressure distribution efficiently and avoid any problem in convergence. Meantime, to decrease the computation cost the mesh size gradually increases from fracture area to the boundaries. Also, to increase the accuracy of the model, the time steps for fracture propagation is 0.01 second. In addition, the effect of fracturing fluid has been directly included in the model which means that the fluid pressure would be applied along the fracture without any simplifying assumption. To validate the model, the results have been compared with KGD approach. The results indicate that in the initial steps the pressure at the wellbore wall is high which decreases with time significantly and eventually it gets a steady and uniform trend. In other words, in the initial steps, the fluid pressure should be high enough to overcome the hoop stress around the wellbore and after some injection periods, the fracturing fluid pressure would reach the breakdown pressure and the fracture starts to initiate and propagate. It is clearly observed that increasing the injection rate would lead to faster propagation of hydraulic fracture and in the models with higher injection rate the fracture tends to grow in the propagation direction. This indirectly means that increasing the injection rate would affect both opening and length of the hydraulic fracture which can result in increasing the productivity. The results reveal that the peak of the normal effective stress profiles corresponds to the fracture tip position, where the fracture opening is zero,and the peak value equals the cohesive strength of the material,as expected.Moreover,with increasing thedistance from the fracture tip,the stress decreases rapidly and approaches the initial stress value. The way that Young’s modulus affects the overall characteristics of hydraulic fracture implies that higher Young’s modulus would lead to longer fractures. In other words, formations with higher Young’s modulus can be fractured easily but the opening of the hydraulic fracture would reduce at the same time. This also indirectly means that Young’s modulus would play an important role in the productivity.}, Keywords = {Hydraulic Fracturing,Finite Element,Fracture Mechanics,Cohesive Element.,}, volume = {17}, Number = {6}, pages = {259-268}, publisher = {Tarbiat Modares University}, title_fa = {مدل‌سازی عددی پدیده شکست هیدرولیکی در محیط پروالاستیک با استفاده از المان چسبنده}, abstract_fa ={از نقطه نظر مهندسی نفت و گاز در چاه‌هایی با نفوذپذیر کم یا چاه‌های آسیب دیده یکی از مهم‌ترین اهداف ، افزایش بهره‌دهی است. روش‌های گوناگونی برای افزایش بازده چاه‌های نفت و گاز با نفوذپذیری پایین وجود دارد. از مهم‌ترین روش‌های افزایش بهره دهی می‌توان به پدیده شکست هیدرولیکی اشاره کرد. در این پژوهش مدل‌سازی دو بعدی شکاف هیدرولیکی با استفاده از روش اجزای محدود و المان‌های چسبنده و با نرم‌افزار آباکوس مورد بررسی قرار گرفته است. گسترش شکاف هیدرولیکی به صورت شبه استاتیکی و در محیط متخلخل و تراوا و با نرخ تزریق سیال ثابت فرض شده است. در این پژوهش اثر سیال به صورت مستقیم در شکاف هیدرولیکی وارد شده است که در نتیجه فشار سیال بدون هیچ گونه ساده سازی در طول شکاف اعمال می‌شود. همچنین تاثیر دو پارامتر نرخ تزریق سیال و مدول الاستیسیته محیط بر روی تنش موثر، فشار و بازشدگی در دهانه شکاف هیدرولیکی مورد بررسی قرار گرفته است. برای صحت سنجی، نتایج مدل‌سازی با روش تحلیلی KGD مقایسه شده است.}, keywords_fa = {شکست هیدرولیکی,اجزای محدود,مکانیک شکست,المان چسبنده,}, url = {http://mcej.modares.ac.ir/article-16-12824-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-12824-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} } @article{ author = {NazariAliAbady, Kh. and Akhtari, A.A.}, title = {Effect of Vertical and Curve blocks on Hydraulic Jump Characteristic in Diverging Rectangular Sections With FLOW-3D Software}, abstract ={The hydraulic jump phenomenon is one of the most common phenomena in open channels. Hydraulic jump is a transition state from supercritical to subcritical flow regime, which normally occurs in conjunction with hydraulic structures, such as spillways, weirs, and sluice gates. A hydraulic jump phenomenon serves a variety of purposes, for instance, to dissipate the energy of flow to prevent bed erosion and aerate water or to facilitate the mixing process of chemicals used for the purification of water. Stilling basins are one of the most common structures for energy dissipation of flow with high velocities. The stilling basin has been accepted to be the most powerful hydraulic structure for the dissipation of the flow energy. The size and geometry of the stilling basin affect the formation of flow patterns, which can be influential for hydraulic performance of the whole system. The depth of water after the jump is related to the energy content of the flow, and any reduction in energy content with increased energy dissipation in the jump will reduce the required depth of flow after the jump. Sometimes these basins are supplied with appurtenances that increase the overall roughness of the basins. This in turn increases the energy dissipation, decreases the sequent depth, and requires a shorter basin for the full development of the hydraulic jump. There are plenty of research studies in the literature regarding the classical hydraulic jump in the usual rectangular straight stilling basin, but less for the hydraulic jump in other cross section shape of basins. Expanding gradually basin with the rectangular cross section acts as two separate hydraulic structures including stilling basin and transition. In this type of structures not only the transition can be eliminated, but the length of the basin will be also much smaller than what is designed for the usual straight basins. Researchers’ studies show that divergence in stilling basins reduce the sequent depth and the length of the jump while increasing the energy losses compared to the classic jumps. In this research, numerical simulation of the hydraulic jump was performed in divergence rectangular sections, and compared with the results of the laboratory, making use of the FLOW-3D software and the standard k-ԑ and RNG k-ԑ turbulence models. The effects of Vertical and Curve blocks on the specification of hydraulic jump were evaluated. The results showed that the standard k-ԑ turbulence model was able to predict the water level profiles in the hydraulic jump in divergence rectangular sections with appropriate and acceptable coincidence. Results showed that the mean relative error of water surface obtained from numerical model and measured values is about 3.55 percent. Also the numerical model showed the vortices that were accrued because of diverging walls as well as experiment investigations. The results show that creating the vertical blocks, reduces the sequent depth as much as 46.27 % and the length of the hydraulic jump as much as 17.64%, while increasing the energy loss as much as 31.57%, compared to the classic hydraulic jumps. The results also show that creating the Curve blocks, reduces the sequent depth as much as 69.76 % and the length of the hydraulic jump as much as 35.29%, while increasing the energy loss as much as 32%, compared to the classic hydraulic jumps.}, Keywords = {Diverging Hydraulic Jump,Curve blocks,Vertical blocks,k-ԑ Turbulence model,FLOW-3D software,}, volume = {17}, Number = {6}, pages = {269-280}, publisher = {Tarbiat Modares University}, title_fa = {تأثیر بلوک های قائم و منحنی بر مشخصات پرش هیدرولیکی در مقاطع مستطیلی واگرا با استفاده از نرم افزار FLOW-3D}, abstract_fa ={یکی از سازه های متداول جهت استهلاک انرژی جریان های پر سرعت، حوضچه آرامش می باشد. بررسی محققین نشان می دهد که واگرایی و زبری های مصنوعی حوضچه های آرامش هر یک باعث کاهش نسبت عمق ثانویه به اولیه، طول پرش و افزایش افت نسبی انرژی نسبت به پرش کلاسیک می شود. در این تحقیق با استفاده از نرم افزار FLOW-3D و مدل های آشفتگی k-ԑ استاندارد و RNG k-ԑ شبیه سازی عددی پرش هیدرولیکی در مقاطع مستطیلی واگرا انجام شده است و با نتایج بدست آمده از بررسی های آزمایشگاهی مورد مقایسه قرار گرفت، درادامه اثرات بلوک قائم و منحنی بر مشخصات پرش هیدرولیکی مورد ارزیابی قرار گرفت. نتایج نشان داد که مدل آشفتگی k-ԑ استاندارد برای پیش بینی پروفیل سطح آب در پرش هیدرولیکی در مقاطع مستطیلی واگرا مناسب بوده و انطباق قابل قبولی دارد. بررسی ها نشان داد که در مقایسه میان بلوک ها، بلوک های منحنی، اثر گذارتر عمل می کنند، طوری که بلوک های منحنی باعث کاهش عمق ثانویه و طول پرش هیدرولیکی به ترتیب 70 و 35 درصد نسبت به پرش کلاسیک شده است و بلوک های قائم، باعث کاهش عمق ثانویه و طول پرش هیدرولیکی به ترتیب 46و 18 درصد نسبت به پرش کلاسیک شده است.}, keywords_fa = {پرش هیدرولیکی واگرا,بلوک قائم,بلوک منحنی,مدل آشفتگی k‏-ԑ,نرم افزار FLOW-3D,}, url = {http://mcej.modares.ac.ir/article-16-15238-en.html}, eprint = {http://mcej.modares.ac.ir/article-16-15238-en.pdf}, journal = {Modares Civil Engineering journal}, issn = {}, eissn = {2476-6763}, year = {2017} }