考虑降雨条件的堆积体滑坡多场特征研究

ACCUMULATION LANDSLIDES UNDER RAINFALL CONDITION-A CASE FROM CHONGQING

重庆市西泉街滑坡于2007年7月中旬遭遇115a一遇的强降雨,导致滑坡产生明显的变形破坏现象,本文在滑坡实际勘察工作的基础上,基于饱和-非饱和渗流理论,考虑降雨入渗的影响,利用有限元分析软件Geo-Studio的不同模块模拟了不同降雨条件下滑坡稳定性的变化情况,进一步对不同降雨条件下滑坡的渗流场、应力场和位移场特征进行了综合分析。研究结果表明:(1)降雨作用下堆积体滑坡体内渗流场和位移场具有很好的相似性,即滑坡体内地下水流速矢量和位移矢量绝对值变化规律具有一致性;(2)滑坡前后缘的位移量与降雨强度和降雨历时均呈正相关性,且滑坡前缘位移量比后缘大;(3)大雨、暴雨和大暴雨持续作用下,XY向最大剪应力在滑坡前缘及前缘陡坎处集中,有局部产生滑动的趋势,而在特大暴雨持续作用下,XY向最大剪应力在滑带附近分布相对均匀,有整体产生滑动的趋势;(4)强降雨作用下堆积体滑坡模拟得到的变形破坏规律主要表现为滑坡前缘首先产生的鼓胀变形破坏牵引滑坡后缘产生拉张变形破坏,破坏规律与实际相符。

The Xiquan Street landslide encountered an especially heavy rain of 1 15 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＆amp;nbsp;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.