中文摘要：

以循环荷载作用下土工格栅与砂土的直剪室内试验结果为基础,对法向循环荷载作用下筋土直剪过程进行三维颗粒流模拟,开发CLUMP颗粒板替代顶墙施加法向循环荷载。与静载作用室内试验结果相对比,数值试验可以从宏细观角度分析土工格栅在直剪试验中筋土作用特性。研究结果表明：离散元PFC数值试验可以较好地再现筋土界面作用特性。相比静载作用情况,法向循环荷载使得试样上部区域和筋土界面区域颗粒位移明显增加,循环荷载峰值谷值交替出现,筋土界面区域孔隙率呈现波动变化,颗粒旋转明显,滑动比较大。随着土工格栅埋深的增加,法向循环荷载影响逐渐减弱,筋土界面剪应力峰值上升,循环荷载弱化了土工格栅的加筋作用。循环荷载作用下土工格栅与土颗粒的咬合力以及颗粒间的静摩擦阻力、滑动摩擦阻力与滚动摩擦阻力是形成土工格栅加筋作用的主要原因。

英文摘要：

Based on the results of direct shear tests between geogrid and sand under cyclic loading,particle flow code （PFC3D） is used to simulate the geogrid direct shear process,and clump particle board is dereloped to substitute the top wall for applying cyclic loading. Which could analgze geogrid shear properties microscopically. The results show that PFC3 D numerical test can better simulate the geogrid-soil inter-face characteristics. Compared with the direct shear tests under static loading,the displacement of particles increased,obviously on the top of the sample and the interface of geogrid-soil,peak and valley of the cyclic loading appear alternately,in the porosity interface of geogrid-soil fluctuates,and sand particles rotates obviously,and sliding fraction is larger. With the deepening of embedded depth,the effects of normal cyclic loading decreased gradually,the peak value of shear stress on geogrid-soil inteface increased,and the cyclic loading weakens the reinforcement effect. The interlocking force,static friction force,sliding friction force and rolling friction force are the main causes for forming the geogrid reinforce effect.