بررسی اثر توامان مکش و درصد لای بر مقاومت برشی حالت بحرانی ماسه لای‎دار غیراشباع

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری مهندسی ژئوتکنیک، دانشکده فنی و مهندسی، دانشگاه بوعلی ‎سینا، همدان، ایران.

2 دانشیار گروه عمران، دانشکده فنی و مهندسی، دانشگاه بوعلی ‎سینا، همدان، ایران.

چکیده

در این پژوهش مقاومت برشی حالت بحرانی یک نوع ماسه با درصدهای مختلف لای در حالت‎های اشباع و غیراشباع بررسی شده است. برای این منظور تعدادی آزمایش سه‎محوری تحکیم‎یافته زهکشی نشده (CU) روی نمونه‎های اشباع و تعدادی آزمایش تحکیم‎یافته زهکشی شده (CD) روی نمونه‎های غیراشباع انجام شده است. نمونه‎ها تحت سه تنش همه‎جانبه 50، 100 و 150 کیلوپاسکال و با در نظرگیری چهار سطح مکش 50، 100، 150 و 250 کیلوپاسکال برای نمونه‎های غیراشباع، در معرض برش قرار گرفتند. نتایج نشان می‎دهد که اگر نمونه‎هایی با eeq برابر ساخته شود، خطوط حالت بحرانی در حالت اشباع و در درصدهای مختلف ریزدانه روی هم قرار می‎گیرد. در حالت غیراشباع و در فضای تنش خالص، خط حالت بحرانی نه‌تنها وابسته به مکش است، بلکه با تغییرات درصد ریزدانه نیز این خطوط تغییر می‎کند. با این حال در حالت تنش مؤثر می‎توان با به‌کارگیری روابط تنش مؤثر مناسب و مفهوم نسبت تخلخل بین‌دانه‌ای معادل، این خطوط را مستقل از مکش و درصد ریزدانه همگرا کرد و به خط حالت بحرانی واحد در فضای تنش ها رسید.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigating the Simultaneous Effect of Suction and Silt Percentage on the Critical State Shear Strength of the Unsaturated Silty Sand

نویسندگان [English]

  • Maziar Abdi 1
  • Mohammad Maleki 2
  • Erfan Chali 1
1 Ph.D. student, Department of Civil Engineering, Bu-Ali Sina University, Hamedan, Iran.
2 Associate Professor, Department of Civil Engineering, Bu-Ali Sina University, Hamedan, Iran.
چکیده [English]

In this study, the critical state shear strength of a type of sand with different silt percentages in saturated and unsaturated states has been investigated. For this purpose, a number of undrained consolidated (CU) and drained consolidated (CD) triaxial tests were performed on saturated and unsaturated samples, respectively. The samples were sheared under confining pressures of 50, 100 and 150 kPa and suction levels of 50, 100, 150 and 250 kPa for unsaturated samples. In the saturated state, the results showed that if samples are remolded with the same eeq, for the different percentages of fines the critical state lines are converged. In the unsaturated state and net stress state, the critical state line is not only dependent on suction, but also changes with changes in the percentage of fines. However, in the effective stress state, by applying the appropriate effective stress relations and the concept of equivalent intergranular skeleton void ratio, these lines can be converged independently of suction and fine content and reach a single critical state line in the stresses space.

کلیدواژه‌ها [English]

  • Unsaturated Silty Sand
  • Shear Strength
  • Critical State
  • Fine Content
  • Equivalent Intergranular Void Ratio
[1] Han, K., Rahardjo, H., & Broms, B. (1995). Effect of hysteresis on the shear strength of a residual soil, In Proceedings of the First International Conference on Unsaturated Soils, Balkema, Rotterdam, The Netherlands, 499-504.
[2] Rahardjo, H., Heng, O. B., & Choon, L. E. (2004). Shear strength of a compacted residual soil from consolidated drained and constant water content triaxial tests, Canadian Geotechnical Journal, 41(3), 421-436. doi: 10.1139/t03-093
[3] Chiu, C. F., Ni, X. W., & Zhang, L. S. (2014). Effect of hydraulic hysteresis on shear strength of unsaturated clay and its prediction using a water retention surface. Engineering geology, 173, 66-73. doi: 10.1016/j.enggeo.2014.02.008 
[4] Wen, T., Shao, L., & Guo, X. (2021). Effect of hysteresis on hydraulic properties of soils under multiple drying and wetting cycles, European Journal of Environmental and Civil Engineering, 25(10), 1750-1762. doi: 10.1080/19648189.2019.1600037
[5] Rasool, A. M., & Kuwano, J. (2022). Effect of wetting stress paths on mechanical behavior and instability of unsaturated soil in stress state space, European Journal of Environmental and Civil Engineering, 26(16), 8346-8365. doi: 10.1080/19648189.2022.2025909
[6] Pereira, A., Feuerharmel, C., Gehling, W. Y. Y., & Bica, A. V. D. (2006). A study on the shear strength envelope of an unsaturated colluvium soil. In Unsaturated soils 2006, 1191-1199. doi: 10.1061/40802(189)97
[7] Estabragh, A., & Javadi, A. (2012). Effect of suction on volume change and shear behaviour of an overconsolidated unsaturated silty soil, Geomechanics and Engineering, 4(1), 55-65. doi: 10.12989/gae.2012.4.1.055
[8] Patil, U. D., Hoyos, L. R., & Puppala, A. J. (2016). Modeling essential elastoplastic features of compacted silty sand via suction-controlled triaxial testing, International Journal of Geomechanics, 16(6), 1-22. doi: 10.1061/(ASCE)GM.1943-5622.0000726
[9] Maleki, M., & Bayat, M. (2012). Experimental evaluation of mechanical behavior of unsaturated silty sand under constant water content condition, Engineering Geology, 141, 45-56. doi: 10.1016/j.enggeo.2012.04.014
[10] Wang, Z. L., Dafalias, Y. F., Li, X. S., & Makdisi, F. I. (2002). State pressure index for modeling sand behavior, Journal of Geotechnical and Geoenvironmental Engineering, 128(6), 511-519. doi: 10.1061/(ASCE)1090-0241(2002)128:6(511)
[11] Gao, Y., Sun, D. A., Zhu, Z., & Xu, Y. (2019). Hydromechanical behavior of unsaturated soil with different initial densities over a wide suction range, Acta Geotechnica, 14(2), 417-428. doi: 10.1007/s11440-018-0662-5
[12] Estabragh, A. R., & Javadi, A. A. (2008). Critical state for overconsolidated unsaturated silty soil, Canadian Geotechnical Journal, 45(3), 408-420. doi: 10.1139/T07-105
[13] Schofield, A. N., & Wroth, P. (1968). Critical state soil mechanics, 310. London: McGraw-hill.
[14] Russell, A. R., & Khalili, N. (2006). A unified bounding surface plasticity model for unsaturated soils, International Journal for Numerical and Analytical Methods in Geomechanics, 30(3), 181-212. doi: 10.1002/nag.475
[15] Alonso, E. E., Gens, A., & Josa, A. (1990). A constitutive model for partially saturated soils, Géotechnique, 40(3), 405-430. doi: 10.1680/geot.1990.40.3.405
[16] Toll, D. G. (1990). A framework for unsaturated soil behavior, Géotechnique, 40(1), 31-44. doi: 10.1680/geot.1990.40.1.31
[17] Maatouk, A., Leroueil, S., & La Rochelle, P. (1995). Yielding and critical state of a collapsible unsaturated silty soil, Géotechnique, 45(3), 465-477. doi: 10.1680/geot.1995.45.3.465
[18] Wheeler, S. J., & Sivakumar, V. (1995). An elasto-plastic critical state framework for unsaturated soil, Géotechnique, 45(1), 35-53. doi: 10.1680/geot.1995.45.1.35
[19] Loret, B., & Khalili, N. (2002). An effective stress elastic–plastic model for unsaturated porous media, Mechanics of Materials, 34(2), 97-116. doi: 10.1016/S0167-6636(01)00092-8
[20] Toll, D. G., & Ong, B. H. (2003). Critical-state parameters for an unsaturated residual sandy clay, Géotechnique, 53(1), 93-103. doi: 0.1680/geot.2003.53.1.93
[21] Khalili, N. G. F. A., Geiser, F., & Blight, G. E. (2004). Effective stress in unsaturated soils: Review with new evidence. International journal of Geomechanics, 4(2), 115-126. doi: 10.1061/(ASCE)1532-3641(2004)4:2(115)
[22] Zhou, W. H., Xu, X., & Garg, A. (2016). Measurement of unsaturated shear strength parameters of silty sand and its correlation with unconfined compressive strength. Measurement, 93, 351-358. doi: 10.1016/j.measurement.2016.07.049
[23] Thevanayagam, S. (1998). Effect of fines and confining stress on undrained shear strength of silty sands, Journal of Geotechnical and Geoenvironmental Engineering, 124(6), 479-491. doi: 10.1061/(ASCE)1090-0241(1998)124:6(479) 
[24] Thevanayagam, S., & Mohan, S. (2000). Intergranular state variables and stress–strain behaviour of silty sands, Géotechnique, 50(1), 1-23. doi: 10.1680/geot.2000.50.1.1
[25] Amini, F., & Qi, G. Z. (2000). Liquefaction testing of stratified silty sands, Journal of Geotechnical and Geoenvironmental Engineering, 126(3), 208-217. doi: 10.1061/(ASCE)1090-0241(2000)126:3(208)
[26] Salgado, R., Bandini, P., & Karim, A. (2000). Shear strength and stiffness of silty sand, Journal of Geotechnical and Geoenvironmental Engineering, 126(5), 451-462. doi: 10.1061/(ASCE)1090-0241(2000)126:5(451)
[27] Polito, C. P., & Martin II, J. R. (2001). Effects of nonplastic fines on the liquefaction resistance of sands, Journal of Geotechnical and Geoenvironmental Engineering, 127(5), 408-415. doi: 10.1061/(ASCE)1090-0241(2001)127:5(408)
[28] Xenaki, V. C., & Athanasopoulos, G. A. (2003). Liquefaction resistance of sand–silt mixtures: an experimental investigation of the effect of fines. Soil Dynamics and Earthquake Engineering, 23(3), 1-12. doi: 10.1016/S0267-7261(02)00210-5
[29] Ni, Q. T. S. T., Tan, T. S., Dasari, G. R., & Hight, D. W. (2004). Contribution of fines to the compressive strength of mixed soils. Géotechnique, 54(9), 561-569. doi: 10.1680/geot.2004.54.9.561
[30] Bobei, D. C., & Lo, S. R. (2005). Reverse behaviour and critical state of sand with small amount of fines. In Proceedings of the 16th International Conference on Soil Mechanics and Geotechnical Engineering, IOS Press, 475-478. doi: 10.3233/978-1-61499-656-9-475
[31] Rahman, M. M., Lo, S. R., & Gnanendran, C. T. (2008). On equivalent granular void ratio and steady state behaviour of loose sand with fines. Canadian Geotechnical Journal, 45(10), 1439-1456. doi: 10.1139/T08-064
[32] Md. Mizanur, R., & Lo, S. R. (2012). Predicting the onset of static liquefaction of loose sand with fines. Journal of Geotechnical and Geoenvironmental Engineering, 138(8), 1037-1041. doi: 10.1061/(ASCE)GT.1943-5606.0000661
[33] Rahman, M. M., & Lo, S. R. (2014). Undrained behavior of sand-fines mixtures and their state parameter, Journal of Geotechnical and Geoenvironmental Engineering, 140(7), 1-12. doi: 10.1061/(ASCE)GT.1943-5606.0001115 
[34] Sadrekarimi, A. (2013). Influence of fines content on liquefied strength of silty sands. Soil Dynamics and Earthquake Engineering, 55, 108-119. doi: 10.1016/j.soildyn.2013.09.008
[35] Mahmoudi, Y., Cherif Taiba, A., Hazout, L., & Belkhatir, M. (2022). Comprehensive laboratory study on stress–strain of granular soils at constant global void ratio: combined effects of fabrics and silt content. Acta Geotechnica, 17(8), 3269-3292. doi: 10.1007/s11440-022-01480-1
[36] Abdi, M., Chali, E., & Maleki, M. (2020). “Behavior of unsaturated sand-silt mixture through equivalent intergranular void ratio concept”, Journal of GeoEngineering, 15(3), 109-121. doi: 10.6310/jog.202009_15(3).1
[37] Chali, E., & Maleki, M. (2021). “Experimental study on mechanical behavior of unsaturated silty sand in constant equivalent granular void ratio”, Geotechnical and Geological Engineering, 39, 735-750. doi: 10.1007/s10706-020-01518-9
[38] Kadivar, M., Manahiloh, K. N., & Kaliakin, V. N. (2021). Laboratory assessment of the mechanical properties of an unsaturated Mid-Atlantic silty sand, Journal of Materials in Civil Engineering, 33(7), 04021163. doi: 10.1061/(ASCE)MT.1943-5533.0003759 
[39] Bishop, A. W. (1959). The principle of effective stress, Teknisk Ukeblad, 39, 859-863. 
[40] Aitchison, G. (1985). Relationships of moisture stress and effective stress functions in unsaturated soils, In Conference of the British National Society of The International Society for Soil Mechanics and Foundation Engineering, London, United Kingdom, 5-20.
[41] Khalili, N., & Khabbaz, M. H. (1998). A unique relationship for χ for the determination of the shear strength of unsaturated soils, Géotechnique, 48(5), 681-687. doi: 10.1680/geot.1998.48.5.681
[42] Bao, C. G., Gong, B. W., & Zhan. L. T. (1998). Properties of unsaturated soils and slope stability of expansive soils, keynote lecture, In Proceedings of the 2nd International Conference on Unsaturated Soils, Beijing, 1, 71-98. 
[43] Ahmadi Naghadeh, R., & Toker, N. K. (2019). Exponential equation for predicting shear strength envelope of unsaturated soils. International Journal of Geomechanics, 19(7), 1-12. doi: 10.1061/(ASCE)GM.1943-5622.0001435
[44] Thevanayagam, S. (2000). Liquefaction potential and undrained fragility of silty soils, In Proceedings of the 12th World Conference Earthquake Engineering, Wellington, New Zealand, 1-8.
[45] Rahman, M. M., & Lo, S. R. (2008). The prediction of equivalent granular steady state line of loose sand with fines, Geomechanics and Geoengineering: An International Journal, 3(3), 179-190. doi: 10.1080/17486020802206867
[46] ASTM D 422-63. (2002). Standard test method for particle-size analysis of soils, West Conshohocken, PA.
[47] ASTM D 4318-10. (2010). Standard test methods for liquid limit, plastic limit, and plasticity index of soils, West Conshohocken, PA.
[48] Wheeler, S., & Sivakumar, V. (2000). “Influence of compaction procedure on the mechanical behaviour of an unsaturated compacted clay”, Géotechnique, 50(4), 369-376. doi: 10.1680/geot.2000.50.4.369
[49] ASTM D 5311-92. (2004). Standard test method for load controlled cyclic triaxial strength of soil, West Conshohocken, PA.
[50] Porcino, D., Diano, V., Triantafyllidis, T., & Wichtmann, T. (2020). Predicting undrained static response of sand with non-plastic fines in terms of equivalent granular state parameter, Acta Geotechnica, 15(4), 867-882. doi: 10.1007/s11440-019-00770-5
[51] Atkinson, J. H., & Bransby, P. (1977). The Mechanics of Soils: an Introduction to Critical State Soil Mechanics, McGraw-Hill Book Company (UK) Limited, England.
[52] Papadopoulou, A., & Tika, T. (2008). The effect of fines on critical state and liquefaction resistance characteristics of non-plastic silty sands, Soils and Foundations, 48(5), 713-725. doi: 10.3208/sandf.48.713
[53] Naeemifar, O., & Yasrobi, S. S. (2012). Collapse surface characteristics of clayey sands, In Proceedings of the Institution of Civil Engineers-Geotechnical Engineering, 165(6), 379-390. doi: 10.1680/geng.9.00058
[54] Fredlund, D. G., & Xing, A. (1994). Equations for the soil-water characteristic curve, Canadian Geotechnical Journal, 31(4), 521-532. doi: 10.1139/t94-061
[55] Kayadelen, C., Sivrikaya, O. S. M. A. N., Taşkıran, T., & Güneyli, H. (2007). Critical-state parameters of an unsaturated residual clayey soil from Turkey. Engineering Geology, 94(1-2), 1-9. doi: 10.1016/j.enggeo.2007.05.008
CAPTCHA Image