含软弱夹层土样变形破坏过程细观数值模拟及分析

基于颗粒流理论，引入接触连接模型和滑动模型，建立了含软弱夹层试样的颗粒流模型。通过颗粒流程序(PFC)数值模型试验，对含软弱夹层试样的强度和破坏发展进行了数值模拟，分别对比了不同围压以及不同夹层参数条件下的应力-应变关系曲线，通过位移矢量场分析了破坏发展趋势。模拟结果表明，一般围压条件下试样沿软弱夹层滑动破坏，但在某特定围压下，软弱夹层的存在并不起主要控制作用；试样应力-应变关系曲线峰值随软弱夹层颗粒的摩擦系数和法向接触刚度的减小而下降，当颗粒法向接触刚度趋近0时，试样加载初始阶段呈现塑性流变特征；夹层颗粒的切向接触刚度只有低于某一特定值时才会使试样应力-应变关系曲线峰值降低。通过分析，得到了土体颗粒细观参数和宏观力学行为的内在联系，并对土体软弱夹层力学性质和渐进破坏过程有了更进一步的认识。

Numerical simulation and analysis of failure process of soil with weak intercalated layer

Based on the theory of particle flow, Particle Flow Code(PFC)model of soil with weak intercalated layer are constituted by adopting the contact-bond model and the slip model. The failure process and strength of sample are studied by PFC numerical simulation to analyze the stress-strain relationship curves of PFC model under different confining pressures and parameters and diagnose the trend of failure via displacement vector fields. The simulation results show that that failure occurs along the weak intercalated layer in the condition of general confining pressures, but in a special confining pressure, failure is not controlled by weak intercalated layer. The peak value of stress-strain relationship curves declines as normal stiffnesses and friction coefficient of weak intercalated layer bring down, the sample will present yielding flow character in the early stage of loading when the friction coefficient approaches 0. The peak value of stress-strain relationship curve declines only when the shear stiffnesses are under a special value. Through analysis, inhesion relations between particle’s micro parameters and macroscopic mechanics actions are gained; and have a further understanding of weak intercalated layer’mechanical properties and progressive failure of soil.