Modares Civil Engineering journal
مهندسی عمران مدرس
MCEJ
Engineering & Technology
http://mcej.modares.ac.ir
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2476-6763
10.22034
fa
jalali
1392
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gregorian
2013
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online
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توسعه یک مدل برای نمایش رفتار مکانیکی خاکهای
ماسهای سیمانیشده
Developement of a Constitutive Model for the Mechanical Behavior of Cemented Sands
چکیده- در این پژوهش، یک مدل برای نمایش رفتار مکانیکی خاک ماسه ای سیمانی شده ارائه شده است. این مدل بر اساس جدا کردن رفتار خاک سیمانی شده به دو بخش بافت غیرسیمانی و باندهای سیمانی و ترکیب رفتار مکانیکی دو بخش با استفاده از معادلات سازگاری تغییر شکل ها و انرژی، طراحی شده است. برای بخش غیرسیمانی از یک مدل برپایه ی پلاستیسیته عمومی استفاده شده که با یک مدل رفتاری برای باندهای سیمانی ترکیب شده است. ترکیب این دو بخش، نتایجی دلخواه برای مدل­سازی رفتار خاک سیمانی شده در شرایط زهکشی شده و زهکشی نشده فراهم کرده است. برای کالیبراسیون این مدل، نتایج مدل­سازی به صورت منحنی های تنش محوری اضافی-کرنش برشی، کرنش حجمی-کرنش برشی و تنش محوری اضافی-تنش مؤثر میانگین با آزمایش های سه محوری انجام شده بر خاک ماسه­ای سیمانی شده با عامل سیمانتاسیون گچی، مقایسه شده و کارکرد مناسب آن در بازه ی گسترده ای از فشارهای همه جانبه و درصد سیمان تایید شده است .
Cemented sandy soils can be found in different parts of nature. Slopes and natural cuts are observed to be stable for long periods of time. Indeed the stability is related to the cementation and bonding between soil grains which induces an equivalent cohesion for coarse grained soil. Several experimental and theoretical studies have been performed to investigate the mechanical behavior of this category of geomaterials. In present research, a constitutive model is proposed for simulating the mechanical behavior of cemented sandy soils. The model is based on separating the mechanical behavior of cemented soil to two different parts; firstly the uncemented soil matrix and secondly the cemented bonds. The generalized plasticity model developed by Manzanal et al. (2011) is used for predicting the mechanical behavior of the uncemented soil matrix. The model is based on critical state concepts and is able to simulate the behavior of sandy soil in a wide range of confining pressures. It contains sixteen parameters which can be determined using ordinary geotechnical tests for the base soil. Also the elastic-plastic damage bond model proposed by Haeri and Hamidi (2009) is used for cemented bonds. The model has two additional parameters and is able to predict the brittle behavior of cemented bonds besides their degradation with increase in shear strain. Peak shear resistance of cemented bonds increases with confining pressure, however, the axial strain associated to the peak shear strength decreases with enhancement of confining stress. Also cement content is considered in this bond model which is its advantage in comparison with similar ones. Both components have been combined together based on deformation consistency and energy equilibrium equations. Deviatoric stress-shear strain curves besides volumetric strain-shear strain ones have been compared with the results of consolidated drained triaxial tests on a gypsum cemented sand to verify the proposed model. Also deviatoric stress-axial strain besides deviatoric stress-mean effective stress curves of model are compared with results of tests in consolidated undrained state. Results of verification indicate good performance of developed model in a wide range of cement contents and confining pressures. The proposed model has two distinct advantages. At first it considers the effect of cement content as a model parameter and shows variation of the results with this parameter. Secondly, it simulates the soil behavior in a wide range of confining pressures which enables using it in the boundary value problem in geotechnical engineering. However, it should be noted that the model predicts the mechanical behavior of cemented sand in cement contents less than floating limit. Increasing the cement content from the floating threshold changes its role from effective bonding between soil grains to a filler of voids. In this condition, the model can not predict the behavior of cemented soil due to the limitations in the elastic-plastic damage bond model applied in present constitutive model.
- ماسه سیمانیشده,مدل رفتاری,آزمایش سه محوری,منحنی تنش-کرنش,فشار حفره ای
cemented sand,Constitutive Model,triaxial test,stress strain curve,pore pressure
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http://mcej.modares.ac.ir/browse.php?a_code=A-10-1000-5031&slc_lang=fa&sid=16
A.
Hamidi
امیر
حمیدی
100319475328460042311
100319475328460042311
Yes
Kharazmi University
دانشگاه خوارزمی
E.
Ravanbakhsh
احسان
روانبخش
100319475328460042312
100319475328460042312
No
Kharazmi University
دانشگاه خوارزمی