非饱和土力学行为的三维离散元分析

基于离散单元法颗粒流理论,土体颗粒单元间采用Hill接触模型来考虑非饱和土中吸力的作用,建立了非饱和土的颗粒流模型。根据室内试验结果对模型细观参数进行标定,开展了固结排水三轴剪切试验离散元数值模拟,揭示了在不同围压和吸力下,模型试样的应力-应变关系与强度特性等宏观力学性质以及细观信息平均配位数的变化规律。根据不同吸力下的莫尔-库伦破坏包线,建立了吸力与抗剪强度参数之间的关系。此外,通过标定室内试验结果中不同含水率下的应力-应变曲线,建立了Hill模型中吸力与含水率的关系。研究结果表明：Hill接触模型可以较好的模拟非饱和土的力学行为,可为非饱和土的离散元模拟提供参考。

Analysis of mechanical behavior for unsaturated soil by three-dimensional discrete elementmethod

Based on the particle flow theory of discrete element method, the Hill contact model is used to consider the suction force in unsaturated soil, and the particle flow model of unsaturated soil is established. According to the results of laboratory tests, the mesoscopic parameters of the model are calibrated, and the discrete element numerical simulation of the triaxial shear test under consolidation and drainage conditions is carried out. The variation laws of the stress-strain relationship and strength characteristics of the model specimens under different confining pressures and suctions are revealed. According to Mohr-Coulomb failure envelope under different suction, the relationship between suction and shear strength parameters is established. In addition, the relationship between suction and water content in Hill model was established by calibrating the stress-strain curves under different water content in laboratory test results. The results show that Hill contact model can better simulate the mechanical behavior of unsaturated soils and can provide a reference for the discrete element simulation of unsaturated soils.