土工袋层间摩擦过程的细观研究

Mesoscopic study of process of interface friction between two soilbags

为了细观上分析层间摩擦作用下袋体及袋内颗粒的受力及运动情况,以铝棒为袋内材料的土工袋层间摩擦试验为例,采用离散单元法对土工袋层间摩擦试验进行了数值模拟计算,研究了土工袋在层间摩擦作用下袋内部颗粒的运动特征。研究结果表明:土工袋受侧向压力作用下袋体各部位的滑动并非同时产生,受力端受到挤压,局部产生轻微移动,随着侧向力的增加,袋体其余部位沿受力方向逐渐发生移动。试验过程中,上层土工袋不仅会发生侧向压缩和平动,同时因受到下层袋体与加载板的摩擦作用而发生滚动,导致上层土工袋内部土颗粒的位移自上而下、从左到右逐渐减小,上、下层袋体产生相对滑动时,摩擦力的存在会导致袋体层间接触部位拉应力增大,袋体易产生受拉破坏。试验及模拟结果较好呈现了土工袋层间摩擦过程,可为土工袋挡墙的设计提供参考。

To understand the force and the movement characteristics of particles in the soilbags under interlayer friction,taking interlayer friction test of soilbag within aluminum rods as an example,the movement characteristics of particles in the bags submitted to interlayer friction was investigated through two distinguished methods： laboratory test on bags filled with aluminum rods and discrete element method simulation. According to the study results,the slide of each part of the bag did not appear at the same time under the lateral force. In fact,at the first stage of lateral compression,the lateral slide only appeared at certain parts of the bag. Then,with the increase of the lateral force,the whole bag slid along the direction of the increment of the lateral force. During the test,the upper soilbag not only exhibited compression and translation,but also rolled due to the action of friction from the lower soilbag and the loading plate. So the displacement of particles in the upper bags decreased from top to bottom and from left to right. Because the two bags appeared the relative sliding,the friction between two bags led to the increase of tensile stress at the interface of the two bags,where the breakage of bags are often observed. Results of test and simulation can present the process of interlayer friction for soilbags,and can provide a reference for the design of walls by using soilbags.