非饱和重塑黄土应变控制等应力比试验三维离散元分析

黄土地区工程建设中有大量填方工程，填方工程中土体可能承受等应力比压缩荷载，为了研究非饱和重塑黄土在较高应力比下的宏微观力学性质，运用应变控制加载方式开展了不同应力比的非饱和黄土等应力比试验离散元数值分析。数值模拟中，考虑颗粒间转动和扭转抗力及范德华力并采用分层欠压法制备均匀松散黄土数值试样，引入粒间引力反映毛细力作用。通过应变加载方式对数值试样开展等吸力的等应力比数值试验表明:离散元数值结果能定性再现室内等应力比试验的压缩和剪切特性；试样力学配位数随平均应力的变化不受应力比的影响；试样偏组构的变化与其初始状态和加载应力比关系密切。

Strain-controlled Constant-stress-ratio Compression Tests on Unsaturated Remolded Loess Using the 3D Discrete Element Method

The loess bear constant stress ratio stress under soil filling projects which are very common in engineering practice in loess areas.Strain-controlled constant-stress-ratio compression tests were carried out on unsaturated loess using the discrete element method(DEM)to investigate macro and micro scopic behavior of unsaturated loess subjected to various stress ratios.Loose and homogenous numerical sample was generated by considering rolling and twisting resistances and van der Waals force in the contact model and using the multi-layer under-compaction method.The adhesive force was incorporated into the contact model to reproduce the capillary force in unsaturated loess.Then,constantstress-ratio compression tests with constant suction were executed by strain-controlled loading method.Results show that the DEM simulation reproduces the compression and shearing behavior of unsaturated loess in laboratory tests.In microscopic behavior,the mechanical coordination number versus mean stress curves are independent on the stress ratio.The deviator fabric variation is controlled by its initial state and loading stress ratio.