基于离散元颗粒抗转模型的平移刚性挡墙被动土压力分析

Distinct element simulation of passive earth pressure against a translating rigid wall using a rolling resistance contact model

将颗粒抗转动模型引入离散元程序中,模拟了砂性填土刚性挡土墙平移过程中的被动土压力发展过程,对比分析了考虑和不考虑抗转两种情况下墙后土压力随位移的变化规律及墙后填土微观物理量的变化规律,揭示了颗粒抗转动能力对墙后土压力大小和分布的影响。研究结果表明,不管是否考虑颗粒抗转动作用,被动土压力沿墙深基本呈线性分布,且合力作用点维持在距墙底1/3墙高处,但考虑颗粒抗转动作用时总土压力随位移量增大的幅度更加明显,且模拟结果更接近Coulomb理论解。平均纯转动率的分析结果表明,挡墙平移时墙底处颗粒转动速度较大,该处能量消散较快;若考虑颗粒抗转动作用时,该处平均纯转动率值增加。

A model considering rolling resistance in particles is introduced into the distinct element method（DEM） for analyzing the earth pressure against a rigid wall subjected to translation movements in the passive state.The evolution of earth pressure with the wall displacement is analyzed together with micro mechanical parameters by comparing the cases with and without considering the rolling resistance of particles in the granular backfill.Results show that the earth pressure increases linearly with the increase of the wall depth regardless of the effect of rolling resistance;and the total thrust acts at approximately one third of the wall height from the base of the wall in both cases.The increase of the resultant earth pressure with displacement is more prominent in the case considering rolling resistance than that neglecting the rolling resistance.The result considering rolling resistance is more close to the classic Coulomb＇s solution.According to the field of average pure rotation rate,the velocity of soil particles adjacent to the base of the rigid wall is larger,implying a quick energy dissipation taking place at that region,and it becomes even larger in the case considering the rolling resistance than that in the case without considering the rolling resistance.