三峡树坪滑坡动力学的有限元模拟

三峡工程是迄今为止最大的水利工程,对库区滑坡灾害的监测和机制研究一直是重要的研究课题。本文利用Terra SAR-X的强度图进行相关计算,求解出2009年5月20日至8月5日期间三峡树坪滑坡的形变场。该形变场特征和树坪滑坡体的地形特征吻合甚好,位移大小、方向和三峡大学对滑坡体的野外观测结果基本吻合。以此高精度位移场为外部约束,结合野外观测资料对滑坡体介质力学性质进行分类并选取边界条件,利用有限元方法对滑坡活动进行动力学计算模拟。计算过程中对滑坡体的滑动面形状、因降雨引起材料参数变化和三峡水库水位等因素分别反演和调整,得出符合其变形和发展过程的滑坡动力学特征。发现软弱带的物性参数决定滑坡体总体滑动量,滑坡体的物性参数决定位移分布的峰值位置。在确定了滑坡动力学特征之后,进一步讨论降雨和库区水位下降对滑坡产生的贡献权重,得出降雨是树坪滑坡的决定因素。

A finite element numerical simulation of landslide dynamics in Shuping, Three Gorges area

The monitoring of landslides in the Three Gorges reservoir area and the research on its mechanism has attracted significant academic attentions. A sub-pixel correlation method dedicated to analyze the TerraSAR-X intensity images is applied to map the displacement field of the Shuping landslide from May 20 to August 5 in 2009. The characteristics of the movement in this period fit well with the terrain of Shuping area. Moreover, the deduced land slide movements agree well with the field observations. We carry out a finite element numerical simulation of the Shuping landslide process constrained using the high resolution and accurate landslide displacement data combined with field observations on slide material geometry, material properties, and the boundary conditions. The landslide mechanisms are determined by providing constraints on the geometry of the slide model and the fluctuation of the reservoir water level and adjusting the rainfall caused materials parameters variation of the model during the finite element numerical simulations. It can be inferred from the numerical simulation that the sliding material properties manifested the displacement magnitude and the properties of the weak sliding belt controlled the pattern of deformation. Based on the simulated landslide mechanism, we conclude that the rainfall played a much more important role than changes of the reservoir water level in manifesting the Shuping landslides.