非饱和土力学行为的三维离散元分析

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

基于离散单元法颗粒流理论,采用Hill接触模型考虑土体颗粒单元间的接触作用,建立非饱和土的强度模型,对固结排水三轴剪切试验进行离散元模拟,分析不同围压和吸力下试样的应力-应变发展过程.研究结果表明:试样的抗剪强度随围压和吸力的增大而提高;随着吸力的增大,应力-应变曲线由应变软化向应变硬化发展,且黏聚力和内摩擦角均呈非线性增加.应用Hill接触模型的颗粒流模型可较好地模拟非饱和土的力学行为,可为非饱和土的强度理论分析和工程实践提供参考.

Based on the discrete element method of particle flow theory,the Hill contact model is used to consider the contact between soil particles,and the strength model of unsaturated soil is established.The three-axis shear test of consolidation and drainage is simulated by discrete element,and the stress-strain development process of the specimen under different confining pressure and suction is analyzed.The results show that the shear strength of the specimen increases with the increase of confining pressure and suction.With the increase of suction,the stress-strain curve develops from strain softening to strain hardening,and the cohesive force and internal friction angle are nonlinearly increased.The particle flow model using Hill contact model can better simulate the mechanical behavior of unsaturated soil,and the results can provide a reference for the strength theory analysis and engineering practice of unsaturated soil.