涵洞减载的颗粒流数值模拟

Discrete Element Analysis of Load Reduction for Culvert

采用PFC2D颗粒流软件提出了一种新的生成初始土层模型的方法(Multi-layer and Multi-gravity Compaction Method即MGCM),可以得到较合理的初始土层应力分布。从细观力学的角度对柔性填料法涵洞减载进行了数值模拟,研究了不同填土高度下涵顶土压力系数的变化规律,及内外土柱相对位移对涵洞上方和两侧受载的影响。研究结果表明:涵顶土压力系数随着填土高度的增加逐渐增加,当填土达到一定高度后其值趋于稳定并略有降低。随着内外土柱相对位移的增加,涵洞上方土层接触力链逐渐发展成拱形状,涵侧土压力逐渐增大,但增幅逐渐减小;涵顶土压力逐渐减小后趋于稳定并略有上升。

A new technique, designated as the Multi-layer and Multi-gravity Compaction Method（MGCM）, capable of generating more reasonable specimens for DEM studies is presented herein. Flexible filling of load reduction for culvert is analyzed by PFC. The coefficient of earth pressure at the top of the culvert under different height of fill, and the load on the upper and both sides of culvert under difference between the inner and outer soil columns are studied. Numerical results indicate that the concentration coefficient increases with the height of the fill, but it approaches the limit value at a certain height of fill, then decreases slightly. With the increase of the relative displacement of the inner and outer soil column, the contact force of the particles above the culvert gradually developed into an arched shape, the pressure of the lateral soil gradually increases, and the pressure of the top soil decreases first and then increases.