土体降雨滑坡中细颗粒运移及效应

The Movement of Fine Grains and Its Effects on the Landslide and Debris Flow Caused by Raining

针对土体中细颗粒迁移对滑坡泥石流启动的影响开展了实验，比较了不同纵横剖面的颗粒级配在不同位置及实验前后的结果。研究发现，沿土体深度方向均是细颗粒下移，中部聚集程度最高；沿坡面方向，在离土面相同距离的位置，后部细颗粒多，前部细颗粒少。可以初步认为，随着降雨入渗，细颗粒逐渐汇集到土体下部和土坡坡角，从而使相应位置的渗透性降低，孔压上升，孔隙水聚集于该处，形成滑动面，最后导致滑坡泥石流。

Experiments are carried out to study the movement of fine grains in soil and its effect on the landslide and debris flow. The grain series at different sections before and after experiments are compared. It is shown that the fine grains move downwards in the direction vertical to the slope surface and mostly are assembled in the middle. The fine grains are more at the tail than at the foreside at the same parallel to the slope surface. It may be thought that the fine grains are assembled at the lower part and foreside of the slope due to the raining and penetration of water, which causes decrease of the permeability at these places. Therefore,the pore pressure increases and pore water are blocked at these places, loading to formation of the sliding face and the landslide or debris flow occurs.