为深入探究筋土界面的细观变形破坏机理,以室内大型直剪试验结果为基础,利用离散元软件PFC3D建立了3种砾石含量(50%、75%和100%)和2种加载方式(法向静荷载和法向循环荷载)下含砾花岗岩残积土-土工织物界面的直剪试验模型,分析了筋土界面孔隙率、配位数、组构各向异性和颗粒旋转情况等细观剪切特性的变化规律。结果表明：试样孔隙率变化量随砾石含量的增大而增大,且主要集中在剪切面附近,法向循环荷载作用也会使其略微增大；界面处的配位数随砾石含量增大分别介于5.19-6.05、4.74-5.77和4.35-5.53之间,颗粒间的接触减少；两种加载方式下试样颗粒的接触力的各向异性主方向均发生了偏转,且法向静荷载作用下的法向接触力相较于法向循环荷载作用下的均更大；砾石含量100%的颗粒平均旋转角度比50%时的更小,法向循环荷载作用会使其略微增大,曲线整体上呈正态分布,最大值位于剪切面附近。

To delve into the micromechanical deformation and failure mechanisms of the geogrid-soil interface, a series of direct shear test models for granite residual soil with geotextiles containing different rock contents (50%, 75%, and 100%) under two loading conditions (normal static load and normal cyclic load) were established using the discrete element software PFC3D, based on the results of large-scale indoor direct shear tests. The study analyzed changes in micromechanical shear characteristics such as porosity, coordination number, fabric anisotropy, and particle rotation at the geogrid-soil interface. The results indicated that the change in sample porosity increased with higher rock content and was primarily concentrated near the shear plane, with normal cyclic loading causing a slight increase as well. The coordination number at the interface ranged between 5.19-6.05, 4.74-5.77, and 4.35-5.53 as the rock content increased, indicating a reduction in particle contacts. Under both loading conditions, the principal direction of anisotropy of contact forces between particles shifted, with the normal contact forces under normal static load being greater than those under normal cyclic load. The average rotation angle of particles with 100% rock content was smaller than that with 50% rock content, and normal cyclic loading caused a slight increase. Overall, the rotation angle distribution was normally distributed, with the maximum value located near the shear plane.

TU375.4

国家自然科学基金资助项目(No. 52078285)