مدلسازی رفتار تراکم پذیری خاکهای دارای ساختار با در نظر گرفتن اثرات دستخوردگی در تعیین فشار پیش تحکیمی

نوع مقاله : پژوهشی اصیل (کامل)

نویسندگان
احد اوریا 1
علی فارسی جانی 2
1 دانشیار گروه عمران(ژئوتکنیک)، دانشکده فنی و مهندسی، دانشگاه محقق اردبیلی، اردبیل،ایران
2 دانشجوی دکتری عمران(ژئوتکنیک)، دانشکده فنی و مهندسی، دانشگاه محقق اردبیلی، اردبیل، ایران
10.22034/23.1.8
چکیده
رفتار تنش-نسبت نسبت تخلخل خاک‌های دارای ساختار هم در مقیاس نیمه لگاریتمی و هم در مقیاس لگاریتمی کامل، غیرخطی می باشد به گونه ای که امکان بیان رفتار این گونه خاک‌ها با یک خط در مقیاس لگاریتمی یا نیمه لگاریتمی امکان پذیر نمی باشد. همچنین یکی از پارامترهای تعیین کننده در بیان رفتار خاکها، تنش پیش تحکیمی می باشد. دستخورگی نمونه ها باعث می شود شکستگی نمودار تنش-نسبت نسبت تخلخل در محل فشار پیش تحکیمی محو و تعیین دقیق فشار پیش تحکیمی از نمودارهای تنش-نسبت تخلخل مشکل شود. ازطرفی با توجه به تقعر منحنی تنش-نسبت نسبت تخلخل خاک‌های دارای ساختار، روشهای مرسوم برای تعیین فشار پیش تحکیمی این خاکها کاربرد ندارند. در این تحقیق براساس نتایج آزمایشگاهی، مدلی برای تراکم‌پذیری و گسیختگی حجمی خاکهای دارای ساختار ارائه شده که براساس تئوری حالت آشفتگی بوده و فقط از یک منحنی پیوسته برای بیان رفتار خاک هم درحالت پیش تحکیمی و هم در حالت عادی تحکیمی استفاده شده است. منحنی های تنش-نسبت نسبت تخلخل خاک در سطح تنش بسیار پایین در شرایط پیش تحکیم یافته با ساختار به نسبت سالم و سطح تنش بسیار بالا در شرایط عادی تحکیمی بعد از تخریب کامل ساختار، بعنوان مجانب های مدل ارائه شده استفاده شده است. با استفاده از یک تابع حالت مشابه سیگموئید، انتقال رفتار خاک از حالت پیش تحکیمی به حالت عادی تحکیمی شبیه سازی شده است. تابع حالت ارائه شده براساس فشار پیش تحکیمی و شاخص دستنخورگی می باشد که با تعیین آن، فشار پیش تحکیمی نیز بصورت تحلیلی مشخص می شود. مقایسه نتایج مدل ارائه شده با مدلهای دیگر قابلیت های مدل ارائه شده را نشان می دهد.

کلیدواژه‌ها

موضوعات

عنوان مقاله English

Modeling the Compression Behavior of Structured Soils Considering the Effects of Sample Disturbance on the Pre-Compression Pressure

نویسندگان English

A. Ouria 1
A. Farsijani 2
1 Ahad Ouria, Ph.D, Associate Professor, Civil Engineering Department, University of Mohaghegh Ardabili, Iran.
2 Ali Farsijani, Ph.D Candidate, Civil Engineering Department, University of Mohaghegh Ardabili, Iran
چکیده English

Natural soils pose an inter particle bonds that makes their compression and failure behavior different than the compression and failure behavior of remolded soils. Different reasons have been suggested for the creatin of inter particle bonds, including natural cementation, carbonating agents, and aging. These classes of soils are called structured soil. Structured soils could also be produced from artificial cementation by cement, lime, and other chemical agents. Overconsolidated generally show different compression behavior in overconsolidated state and normally consolidated state and their compression index in both states are different. Structured materials show a highly nonlinear compression behavior after initial yielding in the normally consolidated state. Their compression index has a large value at the beginning of the virgin yielding and decreases as the structure of the soil crashes. This highly nonlinear behavior prevents from adapting the conventional linear compression models in both semilogarithmic or fully logarithmic scale in e-log(p) or ln(1+e)-ln(p) spaces. On the other hand, sampling disturbs the soil samples and destructs the soil structure. Although there are several new sampling methods and apparatuses to reduce the disturbance of the samples, however the disturbance could not be completely removed from sampling procedure. Disturbance of the samples makes the determination of the precompression pressure of the soil samples where the compression regime of the soil changes, very complicated. There are several methods for determination of the precompression pressure of disturbed samples that most of them are based on graphical procedures. This paper presents a contentious compression model for volumetric compression and yielding of structured soils considering the effect of the sample disturbance on the determination of the precompression pressure. The compression behavior of the structured soil in low stress levels where the structure of the soil is relatively intact (RI) is known and can be measured in the laboratory. Also, the compression behavior of a structured soil at very high stress level where in fully adjusted (FA) state is similar to the compression behavior of the same soil in remolded state. The compression behavior of the structured soil with some degree of the disturbance must lays between these two reference states. Based on the Disturbed State Concept (DSC) the behavior of any complex phenomenon between two reference states of RI and FA could be completely described using a coupling mechanism called the state function. In this paper, the compression curve of the soil in low stress levels at overconsolidated state was considered as RI state and the compression curve of the same soil in the remolded state was considered as FA state. A continuous sigmoid form state function was proposed for description of the continuous change of the e-log(p) curve of the soil from overconsolidated state to normally consolidated states. The effect of the sample disturbance was introduced in the state function by an intactness parameter. High values of the intactness parameter produce distinctive changes from overconsolidated regime to normally consolidated regime that is the main character of intact samples. Based on the proposed model the precompression pressure could be determined minimizing the deviations of the predicted results from observed results in compression test. The proposed model was verified by data reported in the literature and also laboratory tests conducted by the authors. The verification of the model showed the ability of the model in determination of the precompression pressure of artificially overconsolidated samples with known precompression pressures more precise than the other methods.

کلیدواژه‌ها English

Disturbed state concept
Structured soil
Compression
Pre-compression pressure
Sample disturbance
1- Mitchell JK, Soga K,(2005). ”Fundamentals of soil behavior”, John Wiley & Sons, US, pp 325-350.
2- Bagherieh, A. R., Farpour, R., Farsijani, A. (2017). The collapse and creep beheviour of kaolin with double porosity structure. Modares Journal of Civil Engineering, 16(20), 11–20. http://mcej.modares.ac.ir/article-16-10663-fa.html
3- Memarzadeh, I., Lashkari, A. & Shourijeh, P.T. Consolidation Behavior of Structured Clayey Soils: A Case Study on Shiraz Fine Alluvial Strata. Int J Civ Eng 16, 1435–1444 (2018). https://doi.org/10.1007/s40999-017-0163-1
4- Garakani, A. A., Haeri, M., Desai, C. S., Ghafouri , M. H. S., (2019) Testing and Constitutive Modeling of Lime-Stabilized Collapsible Loess. II: Modeling and Validations, Int. J. Geomechanics, 19(4) 10.1061/(ASCE)GM.1943-5622.0001386
5- Ouria, A., Karamzadegan, S., Emami, S., “Interface properties of a cement coated geocomposite”, Construction and Building Materials, Volume 266, Part B, 2021, 121014. https://doi.org/10.1016/j.conbuildmat.2020.121014
6- Sangrey, D. A. (1972). “Naturally cemented sensitive soils.” G_eotechnique,22(1), 139–152.
7- Ouria, A., & Behboodi, T. (2017). Compressibility of Cement Treated Soft Soils. Journal of Civil and Environmental Engineering, 47.1(86), 1–9. https://ceej.tabrizu.ac.ir/article_6273.html
8- Chowdhury B, Haque A, Muhunthan B, (2014 ). “New pressure-void ratio relationship for structured soils in the virgin compression range”, Journal of Geotechnical and Geoenvironmental Engineering, 140 (8), 06014009.
9- Ouria, A. (2017). “Disturbed state concept-based constitutive model for structured soils.” International Journal of Geomechanics, 17(7) Doi:10.1061/(ASCE)GM.1943-5622.0000883.
10- Shogaki, T., and Kaneko, M. (1994), Effects of Sample Disturbance on Strength and Consolidation Parameters of Soft Clay, Soils and Foundations, 34(3) 1-10.
11- Rouainia, M., and Muir Wood, D. (2000). “A kinematic hardening constitutive model for natural clays with loss of structure.” Geotechnique, 50(2), 153–164
12- Yang, C., Liu, X., Yang, C., and Carter, J. P. (2015). “Constitutive modelling of Otaniemi soft clay in both natural and reconstituted states.” Comput. Geotech, , 70, 83–95.
13- Liu, M. D., and Carter, J. P. (2000a). “Modelling the destructuring of soils during virgin compression.” Geotechnique, 50(4), 479–483.
14- Liu, M. D., Carter, J. P., and Desai, C. S. (2003). “Modeling compression behavior of structured geomaterials.” Int. J. Geomech., 10.1061 /(ASCE)1532-3641(2003)3:2(191), 191–204
15- Horpibulsuk, S., Suddeepong, A., Chinkulkijniwat, A., and Liu, M. D. (2012). “Strength and compressibility of lightweight cemented clays.” Appl. Clay Sci., 69, 11–21.
16- Horpibulsuk, S., Rachan, R., Suddeepong, A., Liu, M. D., and Du, Y. J. (2013). “Compressibility of lightweight cemented clays.” Eng. Geol., 159, 59–66.
17- Zhu, E. Y., and Yao, Y. P. (2015). “Structured UH model for clays.”Transp. Geotech., 3, 68–79.
18- Lagioia, R., and Nova, R. (1995). “An experimental and theoretical study of the behaviour of a
calcarenite in triaxial compression.” Geotechnique, 45(4), 633–648
19- Ouria, A., Ranjbarnia, M., and Vaezipour, D. (2018). “A Failure Criterion for Weak Cemented Soils.” Journal of Civil and Environmental Engineering, 48.3(92), 13–21.
20- Casagrande, A. 1936. Determination of preconsolidation load and its practical significance. In Proceedings of the First International Conference on Soil Mechanics and Foundation Engineering, Cambridge, Mass., 22–26 June 1936.pp. 60–64.
21- Pacheco Silva, F. 1970. A new graphical construction for determination of the pre-consolidation stress of a soil sample. In Proceedings of the 4th Brazilian Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, Brazil. pp. 225–232.
22- Burland, J.B. 1990. On the compressibility and shear strength of natural clays. Géotechnique, 40(3): 329–378. doi:10.1680/geot.1990.40.3.329
23- Jacobsen, H.M. 1992. Bestemmelse af forbelastningstryk I laboratoriet. NordiskeGeotecknikermde NGM-92, Aalborg, 28–30 May 1992. pp. 455–460
24- Boone, S.J. 2010. A critical reappraisal of “preconsolidation pressure” interpretations using the oedometer test. Canadian Geotechnical Journal, 47(3): 281–296. doi:10.1139/T09-093.
25- Butterfield, R. 1979. A natural compression law for soils (an advance on e-logp). Géotechnique, 29(4): 469–480. doi:10.1680/geot.1979.29.4.469.
26- Oikawa, H. 1987. Compression curve of soft soils. Soils and Foundations, 27(3):99–104. doi:10.3208/sandf1972.27.3_99.
27- Jose, B.T., Sridharan, A., and Abraham, B.M. 1989. Log-log method for determination of preconsolidation pressure. Geotechnical Testing Journal, 12(3): 230–237. doi:10.1520/GTJ10974J
28- Onitsuka, K., Hong, Z., Hara, Y., and Yoshitake, S. 1995. Interpretation of oedometer test data for natural clays. Soils and Foundations, 35(3): 61–70. doi:10. 3208/sandf.35.61.
29- Bjerrum, L. 1967. Engineering geology of Norwegian normally-consolidatedmarine clays as related to settlements of buildings. Géotechnique, 17(2): 83–118. doi:10.1680/geot.1967.17.2.83.
30- Becker, D.E., Crooks, J.H.A., Been, K., and Jefferies, M.G. 1987. Work as a criterion for determining in situ and yield stresses in clays. Canadian Geotechnical Journal, 24(4): 549–564. doi:10.1139/t87-070.
31- Wang, L.B., and Frost, J.D. 2004. Dissipated strain energy method for determining preconsolidation pressure. Canadian Geotechnical Journal, 41(4): 760–768. doi:10.1139/t04-013.
32- Umar, M., & Sadrekarimi, A. (2016). Accuracy of determining pre-consolidation pressure from laboratory tests. Canadian Geotechnical Journal, 54(3), 441–450. https://doi.org/10.1139/cgj-2016-0203
33- Desai, C. S. (2001). Mechanics of materials and interfaces: The disturbed state concept, CRC, Boca Raton, FL.
34- Desai, C. S., and Toth, J. (1996). “Disturbed state constitutive modeling based on stress-strain and non-destructive behavior.” Int. J. Solids Struct., 33(11), 1619–1650.
35- Desai, C. S., and Wang, Z. C. (2003). “Disturbed state model for porous saturated materials.” Int. J. Geomech., 10.1061/(ASCE)1532 -3641(2003)3:2(260), 260–264.
36- Desai, C. S. (2016). “Disturbed state concept as unified constitutive modeling approach.” J. Rock Mech. Geotech. Eng., 8(3), 277–293
37- Desai, C. S. (1974). “A consistent finite element technique for work- softening behavior.” Proc., Int. Conf. on Computational Methods in Nonlinear Mechanics, J. T. Oden, et al., eds., Texas Institute for Computational Mechanics, Austin, TX.
38- Ouria, A., Desai, C. S., and Toufigh, V. (2015). “Disturbed state concept-based solution for consolidation of plastic clays under cyclic loading.” International Journal of Geomechanics, 15(1). doi: 10.1061/(ASCE)GM.1943-5622.0000336
39- Farsijani, A., and Ouria, A. A Compression Model for Unsaturated Collapsible soils, (2021) Accepted for publication, Modares Journal of Civil Engineering.
40- Farsijani, A., and Ouria, A. (2021) Constitutive Modeling the Stress-Strain and Failure Behavior of Structured Soils Based on HISS Model. Modares Journal of Civil Engineering, 21(4), 231–250. http://mcej.modares.ac.ir/article-16-52042-en.html
41- Kucharavy, D., & De Guio, R. (2011). Application of S-shaped curves. Procedia Engineering, 9, 559–572. https://doi.org/https://doi.org/10.1016/j.proeng.2011.03.142
42- Tavenas, F., Jean, P., Leblond, P., and Leroueil, S. (1983). “The permeability of natural soft clays. Part II: Permeability characteristics.” Can. Geotech. J., 20(4), 645–660
43- Yong, R. N., and Nagaraj, T. S. (1977). “Investigation of fabric and compressibility of a sensitive clay.” Proc., Int. Symp. on Soft Clay, Asian Institute of Technology, Bangkok, Thailand, 327–333.2
44- Tanaka, H., and Locat, J. (1999). “A microstructural investigation of Osaka Bay clay: The impact of microfossils on its mechanical behaviour.” Can. Geotech. J., 36(3), 493–508011.03.142
45- Medero; G.M., Schnaid; F; Gehling., "Oedometer Behavior of an Artificial Cemented Highly Collapsible Soil", J. Geotech. Geoenviron. Eng, 2009, 135:840-843.
مهندسی عمران مدرس
دوره 23، شماره 1
فروردین و اردیبهشت 1402
صفحه 119-134