均匀颗粒间接触冲刷的颗粒流数值模拟

Particle flow simulation for contact erosion between uniform particles

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。

Contact erosion easily occurs at the interface between two soil layers subjected to a groundwater flow. Particles of the fine soils are eroded by the flow and transported through the pores of the coarse layer, which may lead to failure of a hydraulic structure. To investigate the meso-mechanism of contact erosion, different layers consisting of uniform particles subjected to a flow parallel to the interface are simulated using the particle flow code. The results show that when the ratio of the effective diameter of the fine layer to the effective pore diameter of the coarse layer is larger than 0.50, the contact erosion does not occur. When the contact erosion happens between layers, the fine particles at the interface will move and be transported by the flows. With the increase in the loss quantity of the fine particles, the coarse particles will sink and the flow velocity will increase.