土与结构物半模直剪试验的颗粒流数值模拟*

使用自主改造的半模直剪仪进行土与钢板、石板的半模直剪试验,竖向荷载分级施加,分别为50kPa,100kPa,150 kPa,200 kPa。应用颗粒流离散元程序——PFC2D对土与结构物在不同法向应力条件下相互作用的半模直剪试验进行数值模拟,研究土与结构物相互作用时接触面土体变形及剪应力的变化情况。分析得出土与结构物相互作用时,土体会呈现出硬化现象。随着法向应力的增加,土的剪应力会升高。在土与结构物的接触面上,形成了一定厚度的剪切带,说明土与结构物的相互作用并不只局限于接触面,而对接触面以上一定厚度内的土体也有影响,但影响范围不大,约为5倍的粒径。土与结构物相互作用时,结构物的性质对土体剪应力的变化影响不大。

Particle flow code numerical simulation of half mould direct shear test between soil and structure

Using self-developed half mould direct shear apparatus,this paper carries out the direct shear test between soil and steel or stone.Different vertical load varies from 50kPa to 200 kPa.Through numerical simulation of shear test of soil and structure under different conditions of stress via PFC2D,this paper studies the shear stress variation and deformation of soil at the interface with the structure.It is concluded that strain softening occurs to soil in the process of shear and the shear stress of soil which rises as vertical stress grows.Shear zone of some thickness appears at the interface when soil and structure interact with each other,which means that the interaction zone covers not only the contact surface but also the soil off the surface to some extent,the range of action in soil extents 5 times’ particle size away from the interface.The surface roughness of structure imposes slight effects upon the change of shear stress.