شبیه سازی عددی رفتار مکانیکی خاک دانه‌ای غیراشباع با ذرات چند گوشه با استفاده از روش اجزای مجزا

مهندسی عمران فردوسی

مقاله 5، دوره 36، شماره 4، دی 1402، صفحه 77-94   

نوع مقاله: مقاله پژوهشی

شناسه دیجیتال (DOI): 10.22067/jfcei.2023.85350.1270

نویسندگان

محمدحسین جلالیان سده؛ سیداحسان سیدی حسینی نیا^*

گروه مهندسی عمران، دانشکده مهندسی، دانشگاه فردوسی مشهد،

چکیده

مدلسازی عددی خاک‌های غیراشباع، امروزه مورد توجه قرار گرفته است. روش اجزای مجزا توانایی مناسبی در مدلسازی منیسک بین ذرات دارد. در این پژوهش رفتار خاک دانه‌ای غیر اشباع با استفاده از مدلسازی دو محوری به شیوه اجزای مجزا مورد بررسی قرار گرفته است. بر خلاف پژوهش‌های گذشته که شکل ذرات به صورت ساده دایروی یا کروی در نظر گرفته می‌شدند، در این مدلسازی از ذرات چند گوشه استفاده شده است که تطابق بیشتری با شکل واقعی ذرات دارد و می‌توان امکان تشکیل منیسک در حفرات مختلف را با توجه به هندسه و آرایش ذرات در کنار هم بررسی کرد. در حالی‌که به دلیل تقارن در ذرات دایروی و کروی، شکل منیسک در بین این ذرات فقط به اندازه ذرات بستگی دارد. با توسعه یک برنامه موجود بر پایه روش اجزای مجزا، ذرات در مکش‌ها و تنش‌های همه جانبه مختلف تحت بارگذاری دو محوری قرار گرفتند. نتایج نشان داد که با افزایش مکش تا حد مشخصی، مقاومت برشی نمونه افزایش می‌یابد و پس از آن با افزایش مکش، مقاومت برشی کاهش ‌می‌یابد. همچنین مشاهده شد که با افزایش تنش همه جانبه، اثر نیروی منیسک بر مقاومت برشی کاهش می‌یابد. مدلسازی ذرات با اندازه‌های مختلف همچنین نشان داد که تاثیر نیروی منیسک بر ذرات کوچک‌تر، بیشتر است و با افزایش اندازه ذرات اثر نیروی منیسک بر مقاومت برشی کمتر می‌شود.

کلیدواژه‌ها

خاک غیر اشباع؛ روش اجزای مجزا؛ ذرات چند گوشه؛ پل مایع؛ تاثیر شکل ذرات

مراجع

 

• G. Fredlund, H. Rahardjo, Soil mechanics for unsaturated soils, John Wiley & Sons, 1993.

[2]   S. D. N. Lourenço, D. Gallipoli, C. E. Augarde, D.G. Toll, P.C. Fisher, “ Congreve, A. Formation and evolution of water menisci in unsaturated granular media,” Géotechnique, vol. 62, pp. 193-199, 2012. doi:10.1680/geot.11.P.034

[3]   R. M. German, Particle packing characteristics. 1989.

[4]   R. Wan, S. Khosravani, M. Pouragha, “ Micromechanical Analysis of Force Transport in Wet Granular Soils,”  Vadose Zone Journal, 13,  2014. doi:10.2136/vzj2013.06.0113

[5]   U. El Shamy, T. Gröger, “ Micromechanical aspects of the shear strength of wet granular soils,”  International Journal for Numerical and Analytical Methods in Geomechanics, vol. 32, pp. 1763-1790, 2008. doi:10.1002/nag.695.

[6]   A.W. Bishop, G. Blight, “ Some aspects of effective stress in saturated and partly saturated soils,”  Geotechnique, vol. 13, pp. 177-197, 1963.

[7]   D.G. Fredlund, N. R. Morgenstern, R. A.Widger, “ The shear strength of unsaturated soils,”  Canadian Geotechnical Journal, vol.15, pp. 313-321, 1978. doi:10.1139/t78-029.

[8]   A. Öberg, G. Sällfors, “ Determination of shear strength parameters of unsaturated silts and sands based on the water retention curve,”  Geotechnical Testing Journal, vol. 20, pp. 40-48, 1997.

[9]   S. Vanapalli, D. Fredlund, D. Pufahl, A. Clifton, “ Model for the prediction of shear strength with respect to soil suction,”  Canadian Geotechnical Journal, vol. 33, pp. 379-392, 1996.

[10] S. Rohm, O. Vilar, “ Shear strength of an unsaturated sandy soil,”  In Proceedings of the Proceedings of the first internatioanal conference on unsaturated soils /unsat'95/Paris/France/6-8 September, vol. 1, 1995.

[11] N. Khalili, M. Khabbaz, “ A unique relationship for χ for the determination of the shear strength of unsaturated soils,” Geotechnique, vol. 48, pp. 681-687, 1998.

[12] G. Eskandari, A. R. Estabragh, A. Soroush, “ Introducing a new technique for evaluating the behavior and volume change of unsaturated soils,”  Ferdowsi Civil Engineering, vol. 25, pp. 31-55, 2014. (In Persian)

[13] R. Baltodano-Goulding, Tensile strength, shear strength and effective stress for unsaturated sand. University of Missouri--Columbia, 2006.

[14] R. Schnellmann, H. Rahardjo, H. R. Schneider, “ Unsaturated shear strength of a silty sand,”  Engineering Geology, vol. 162, pp. 88-96, 2013. doi: 10.1016/j.enggeo.2013.05.011.

[15] S. L. Houston, N. Perez-Garcia, W.N. Houston, “ Shear strength and shear-induced volume change behavior of unsaturated soils from a triaxial test program,”  Journal of geotechnical and geoenvironmental engineering, vol. 134, pp. 1619-1632, 2008.

[16] I. J. Alhani, M. J. b. M. Noor, M. A. M. Al-Bared, I. S. H. Harahap, W. M. Albadri, “ Mechanical response of saturated and unsaturated gravels of different sizes in drained triaxial testing,”  Acta Geotechnica, vol. 15, pp. 3075-3093, 2020.

[17] W. M. Albadri, M. J. M. Noor, I. J. Alhani, “ The relationship between the shear strength and water retention curve of unsaturated sand at different hydraulic phases,”  Acta Geotechnica, vol. 16, pp. 2821-2835, 2021.

[18] N. Lu, B. Wu, C. Tan, “ A tensile strength apparatus for cohesionless soils,”  Advanced experimental unsaturated soil mechanics, pp. 105-110, 2005.

[19] N. Lu, B. Wu, C.P. Tan, “ Tensile Strength Characteristics of Unsaturated Sands,”  Journal of Geotechnical and Geoenvironmental Engineering, vol. 133, pp. 144-154, 2007. doi:10.1061/(ASCE)1090-0241(2007)133:2(144).

[20] W.T. Oh, S. K. Vanapalli, A. J. Puppala, “ Semi-empirical model for the prediction of modulus of elasticity for unsaturated soils,”  Canadian Geotechnical Journal, vol. 46, pp. 903-914, 2009. doi:10.1139/T09-030.

[21] E. Seyedi Hosseininia, “ Investigating the micromechanical evolutions within inherently anisotropic granular materials using discrete element method,”  Granular Matter, vol. 14, pp. 483-503, 2012.

[22] P. A. Cundall, O. D. L. Strack, “ A discrete numerical model for granular assemblies,”  Géotechnique, vol. 29, pp. 47-65, 1979. doi:10.1680/geot.1979.29.1.47.

[23] A. Mirghasemi, L. Rothenburg, E. Matyas, “ Numerical simulations of assemblies of two-dimensional polygon-shaped particles and effects of confining pressure on shear strength,”  Soils and Foundations, vol. 37, pp. 43-52, 1997.

[24] E. Seyedi Hosseininia, A. Mirghasemi, “ Numerical simulation of breakage of two-dimensional polygon-shaped particles using discrete element method,”  Powder Technology, vol. 166, pp. 100-112, 2006.

[25] E. Seyedi Hosseininia, A. Mirghasemi, “ Effect of particle breakage on the behavior of simulated angular particle assemblies,”  China Particuology, vol. 5, pp. 328-336, 2007.

[26] E. Seyedi Hosseininia, “ Discrete element modeling of inherently anisotropic granular assemblies with polygonal particles,”  Particuology, vol. 10, pp. 542-552, 2012.

[27] E. Seyedi Hosseininia, “ Stress–force–fabric relationship for planar granular materials,” Géotechnique, vol. 63, pp. 830-841, 2013.

[28] E. Seyedi Hosseininia, “ A micromechanical study on the stress rotation in granular materials due to fabric evolution,”  Powder Technology, vol. 283, pp. 462-474, 2015.

[29] M. Khabazian, E. Seyedi Hosseininia, “ Instability of saturated granular materials in biaxial loading with polygonal particles using discrete element Method (DEM),”  Powder Technology, vol. 363, pp. 428-441, 2020.

[30] S. Honari, E. Seyedi Hosseininia, “ Particulate modeling of sand production using coupled DEM-LBM,”  Energies, vol. 14, pp. 906, 2021.

[31] M. J. Jiang, S. Leroueil, J. M. Konrad, “ Insight into shear strength functions of unsaturated granulates by DEM analyses,”  Computers and Geotechnics, vol. 31, pp. 473-489, 2004.

doi:10.1016/j.compgeo.2004.07.001

[32] K. Tourani, R. Mahboubi, E. Seyedi Hosseininia, “ Discrete Element Method for Modeling the Mechanical Behavior of Unsaturated Granular Material,” Journal of Computational Methods In Engineering, vol. 35, pp. 157-181, 2016. doi:10.18869/acadpub.jcme.35.1.157.

[33] L. Scholtès, B. Chareyre, F. Nicot, F. Darve, “ Micromechanics of granular materials with capillary effects,”  International Journal of Engineering Science, vol. 47, pp. 64-75, 2009. doi:10.1016/j.ijengsci.2008.07.002,

[34] Z. Shen, M. Jiang, C. Thornton, “ Shear strength of unsaturated granular soils: three-dimensional discrete element analyses,”  Granular Matter, vol. 18, pp. 37, 2016. doi:10.1007/s10035-016-0645-x.

[35] R. Asadi, A. Mirghasemi, “ Numerical investigation of particle shape on mechanical behaviour of unsaturated granular soils using elliptical particles,”  Advanced Powder Technology, vol. 29, pp. 3087-3099, 2018.

[36] J. A. Gili, E. E. Alonso, “ Microstructural deformation mechanisms of unsaturated granular soils,”  International Journal for Numerical and Analytical Methods in Geomechanics, vol. 26, pp. 433-468, 2002. doi:10.1002/nag.206.

[37] V. Richefeu, M. S. El Youssoufi, R. Peyroux, F. Radjai, “ A model of capillary cohesion for numerical simulations of 3D polydisperse granular media,”  International Journal for Numerical and Analytical Methods in Geomechanics, vol. 32, pp. 1365-1383, 2008.

[38] M. J. Jiang, T. Li, H. J. Hu, C. Thornton, “ DEM analyses of one-dimensional compression and collapse behaviour of unsaturated structural loess,”  Computers and Geotechnics, vol. 60, pp. 47-60, 2014. doi:10.1016/j.compgeo.2014.04.002.

[39] B. Kim, S. Park, S. Kato, “ DEM simulation of collapse behaviours of unsaturated granular materials under general stress states,”  Computers and Geotechnics, vol. 42, pp. 52-61, 2012.

[40] M. Khabazian, A. A. Mirghasemi, H. Bayesteh, “ Compressibility of montmorillonite/kaolinite mixtures in consolidation testing using discrete element method,”  Computers and Geotechnics, vol. 104, pp. 271-280, 2018.

[41] M. Khabazian, A. A. Mirghasemi, H. Bayesteh, “ Discrete-element simulation of drying effect on the volume and equivalent effective stress of kaolinite,”  Géotechnique, vol. 72, pp. 95-107, 2022.

[42] G. Lian, C. Thornton, M. J. Adams, “ A theoretical study of the liquid bridge forces between two rigid spherical bodies,”  Journal of colloid and interface science, vol. 161, pp. 138-147, 1993.

[43] G. C. Cho, J. C. Santamarina, “ Unsaturated particulate materials—particle-level studies,”  Journal of geotechnical and geoenvironmental engineering, vol. 127, pp. 84-96, 2001.

[44] F. Soulie, M. S. El Youssoufi, F. Cherblanc, C. Saix, “ Capillary cohesion and mechanical strength of polydisperse granular materials,”  The European Physical Journal E: Soft Matter and Biological Physics, vol. 21, pp. 349-357, 2006.

[45] R. Fisher, “ On the capillary forces in an ideal soil; correction of formulae given by WB Haines,”  The Journal of Agricultural Science, vol. 16, pp. 492-505, 1926.

[46].L. Ning, W. J. Likos, “ Unsaturated soil mechanics,”  John Wiley & Sons Inc, New Jersey, 2004.

[47] Y. Chen, Y. Zhao, H. Gao, J. Zheng, “ Liquid bridge force between two unequal-sized spheres or a sphere and a plane,”  Particuology, vol. 9, pp. 374-380, 2011.

[48] R. J. Bathurst, “ A study of stress and anisotropy in idealized granular assemblies,” 1987.

[49] R. R. Olivera Bonilla, “ Numerical simulations of undrained granular media,”  2004.

[50] S. Vanapalli, W. Oh, “ A model for predicting the modulus of elasticity of unsaturated soils using the soil-water characteristic curve,”  International Journal of Geotechnical Engineering, vol. 4, pp. 425-433, 2010.