ACCUMULATION LANDSLIDES UNDER RAINFALL CONDITION-A CASE FROM CHONGQING

The Xiquan Street landslide encountered an especially heavy rain of 115 years return period in middle July 2007. The heavy rainfall led to an obvious deformation failure phenomenon. This paper is based on the survey work and the saturated-unsaturated seepage theory. By considered the rainfall infiltration, it uses the finite element analysis software Geo-Studio to simulate the changes of the landslide stability for different rain conditions. Then the landslide seepage field, stress field and displacement field for different rain conditions are further studied through the numerical simulation method. The results show the following result. (1)The seepage field and displacement field of the landslide have good similarity under the action of rainfall. Namely the groundwater velocity vector and displacement vector have consistent variations. (2)Displacements of the front edge and back edge of the landslide have positive correlation with the rainfall density and rainfall duration. The displacement of front edge is bigger than that of the back edge. (3)Under the continuous function of rainstorm and heavy rainstorm, the X-Y direction max shear stress is centralized at the front of the landslide and the scarp place. The landslide has a sliding tendency at local area. Under the sustaining action of torrential rain, the maximum shear stress in the X-Y direction distributes relatively uniform near the sliding zone. The landslide has an integral sliding tendency. (4)Under the heavy rainfall, the landslide deformation damage law is mainly as follows: first bulging deformation is at front edge, then the tensile deformation appears at the back edge, which is consistent with the actual deformation.