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成层土在渗流作用下容易发生接触冲刷,细土层中的颗粒从粗土层孔隙中被水流带走,接触冲刷的持续发展会对水工建筑物产生严重的后果。为了从细观角度研究接触冲刷的发生机理,对五组由均匀颗粒组成的土层间的接触冲刷现象进行了颗粒流数值模拟。数值模拟结果表明,当细粒层的有效直径与粗粒层的有效孔隙直径之比大于0.50时,两土层间不会发生接触冲刷。当两土层发生接触冲刷时,接触面处的细颗粒会被水流带起从粗颗粒孔隙中冲出,随着细颗粒流失量的增加,上层粗颗粒逐渐下沉,渗透流速逐渐增加。
Stratified soil prone to contact erosion under seepage, fine soil layer of particles from the coarse soil layer by the flow of water away, the continuous development of contact erosion hydraulic structures will have serious consequences. In order to study the mechanism of contact erosion from the microscopic point of view, particle flow numerical simulation was conducted on the contact erosion phenomenon among five groups of soil layers composed of uniform particles. The numerical simulation results show that when the ratio of the effective diameter of the fine-grained layer to the effective diameter of the coarse-grained layer is greater than 0.50, contact erosion will not occur between the two soil layers. When contact erosion occurs between two soil layers, the fine particles at the contact surface will be washed away by the water flow from the coarse grain pores. As the fine grain loss increases, the upper coarse grains gradually sink and the permeate flow rate gradually increases.