离散元-有限差分跨尺度耦合下桩与土体稳定性细观数值分析

Meso-numerical analysis of pile and soil stability under discrete element-finite difference multi-scale coupling

为准确分析桩体宏观变形与周围土颗粒细观力学行为,采用离散元-有限差分的跨尺度耦合进行桩和土体接触过程中的稳定性分析,研究桩下沉过程中周围土体的细观变形、应力分布和桩体自身变化情况,通过FLAC3D建立桩和外部土体有限差分网格单元,对桩周围侧土体应用PFC3D离散元建立土颗粒微观结构模型。研究结果表明:离散元与有限差分耦合方案能够模拟桩周围土体细观力学行为;外部区域土体位移场呈包裹式C形对称分布,应力场以竖直应力为主导,离散元土颗粒接触力链网格以树根状向周围递减削弱分布;桩弹性单元体下沉时,应力场和位移场均有分层现象,应力场以压应力为主,但存在局部拉应力即反弹现象。

To accurately analyze the macro deformation of pile and the micromechanical behavior of surrounding soil particles,discrete element-finite difference multi-scale coupling is used to study the stability analysis of the pile and soil in the contact process,and then the micro-deformation,stress distribution and changes of the pile itself during the pile sinking process is studied.The finite difference mesh of the pile and the external soil is established by FLAC3D.The soil particle microstructure model of the soil around the pile is established by PFC3D discrete element.The results show that the coupling scheme of discrete element and finite difference can be used to simulate the micromechanical behavior of the soil around the pile.The soil displacement field in the outer region is symmetrically distributed in a"wrapped C"shape,and the stress field is dominated by vertical stress.The soil particle contact force chain mesh is gradually weakened and distributed in the shape of tree roots.While the pile elastic element body sinks,the stress field and displacement field are both stratified,and the stress field is mainly compressive,but there is local tensile stress,that is rebound phenomenon.