考慮地下水位變化之擬似三維邊坡穩定模式之建立

Abstract

本研究旨在以極限平衡法建立擬似三維邊坡穩定模式，除可完整考慮實際崩塌情況與地形變化外，更可避免三維模式之龐大計算量。模式中採用Green-Ampt入滲理論結合一維傾斜岩盤之Boussinesq方程式以考慮降雨入滲與地下水位之變化，將三維已知可能破壞土體，切割為數個二維切面，各切面以簡化Bishop切片法計算其安全係數，再依權重計算整體安全係數，在不考慮側向出入流條件下，藉以探討三維邊坡因土壤滲透性、降雨特性、降雨雨型、岩盤傾斜角度、地形幾何與土壤分布對其穩定性之影響。

The purpose of this study is to develop a quasi-three-dimensional slope stability model based on limit equilibrium method for overcoming the huge computational effort and taking realistic conditions into consideration. The rainfall infiltration and groundwater level variation were simulated by solving the Green-Ampt theory and the one-dimensional Boussinesq equation for sloping aquifer simultaneously. The three-dimensional system was divided into several two-dimensional layers. The stability of each layer was analyzed by using the simplified Bishop method. The three-dimensional stability condition with rainfall infiltration over time was therefore calculated by employing a weighted procedure where weighting was based upon arc-length or area of each layer. Under neglecting lateral flows, the effects of soil permeability, rainfall characters, rainfall patterns, inclined angle of rock layer, topography and soil properties on slope stability were discussed.