考虑摩擦系数和颗粒强度劣化效应的堆石体湿化细观数值模拟

Numerical Simulation of Rockfill Wetting Considering Deterioration of Friction Coefficient and Bond Strength

堆石体遇水之后,水的润滑作用会导致颗粒之间的滑移和重新排列,水的软化作用则会导致颗粒破碎增加。在考虑颗粒破碎的连续-离散耦合分析方法(FDEM)中,引入代表水对于堆石体颗粒间摩擦系数和颗粒强度劣化作用的湿化模型,并按照室内单线法湿化试验的步骤进行了一系列数值试验。数值试验得到的湿化轴向应变与室内试验结果接近,表明水对于颗粒间摩擦系数和颗粒强度的劣化作用是产生湿化轴向应变的主要原因,堆石体颗粒间摩擦系数的降低是引起湿化轴向应变的主要原因,其次是颗粒强度的降低。湿化过程中的颗粒破碎分布呈现出局部集中的现象。湿化后颗粒之间的法向接触力平均值略有增加而切向接触力平均值则下降明显。

Due to wetting, water enables a lubrication at inter-particle contact points which lead to rockfill particles＇ sliding and rearrangement. What＇s more, water can reduce bond strength, thus causing particle breakage to increase. A wetting model that represents weakening effect of water on the contact friction and bond strength is then introduced to the finite-discrete element method （FDEM） considering particle breakage. A series of numerical tests are performed according to the steps of single -line indoor wetting tests. The numerical test results are close to those of indoor tests, which show that water＇s weakening effect on the contact friction coefficient and bond strength is the main mechanism that causes axial strain in the wetting process. Water＇s weakening effect on the contact friction coefficient is the main mechanism that causes axial strain in the wetting process and water＇s weakening effect on the bond strength plays a secondary role. The distribution of particle breakage can be characterized by a phenomenon of local crisis. Average normal contact force is a slight larger and tangential force is evidently smaller after wetting than that before wetting.