順向坡滑動是台灣邊坡破壞中最普遍發生者，加上台灣的地質多由砂岩及頁岩組成，此兩種岩性較為脆弱。近年來，高強度及長延時的降雨，對於台灣地質有劇烈的影響，例如水由表面風化岩層之裂隙滲入而降低岩石的強度，或使土壤中的孔隙水壓力上升，因而降低土壤的剪阻抗力，產生山坡滑動及土石流，影響民生安全。
本研究藉由離散元素法(discrete element method)模擬不同型態及尺度順向坡在不同水位條件下之滑動過程與堆積行為分析其破壞模式，亦將探討岩層中水的浮力對於模擬的影響。其數值模型建置參考曾煒傑(2015)及林育槿(2016)之離心機物理試驗模型。
本研究方法首先對於數值模型進行弱化區指令修正及參數調整，並比對物理試驗結果。整合三組數值模型使用之參數，包含乾燥顆粒間之摩擦係數與泡水弱化後顆粒間之摩擦係數，統整後乾燥摩擦係數採用0.7而弱化後摩擦係數採用0.3。參數確認後，進行模擬分析，分析項目包含邊坡的滑動過程、堆積結果、岩層的位移變化量與岩層平均滑動速度量。
本研究模擬結果中，順向坡的滑動破壞模式會依據岩層組構而有不同，單層互層且層面角度30度順向坡為「坡腳移除型滑動」，單層互層且層面角度60度順向坡為「坡腳鼓脹型滑動」，厚薄夾層且層面角度30度順向坡為「落石破壞模式」三種破壞模式。
希望藉由本研究之模擬結果分析不同型態及尺度順向坡滑動破壞的影響範圍，提供資訊予防災單位參考，降低順向坡滑動所帶來的災害。

Dip slope sliding is the most occurrence of slope disaster in Taiwan and the geology of Taiwan mostly consists of sedimentary rocks like sandstone and shale, both are very weak rocks. In recent years, the rainfall intensity enhancement and the influence time lengthened, had the severe influence on the geology of Taiwan. For instance, water easily seeps through aperture of rocks and reduces rock strength, or increases the pore water pressure thus decrease the shear resistance of soil. Due to above reasons, slope easily to produce slide and mudslide.
In this study, the discrete element method is used to simulate the sliding process and the deposition behavior of different types and scale slopes under different water level conditions, and discusses the effect of floating in numerical simulation. The numerical model is based on the centrifuge physical test model of Zeng, W. J. (2015) and Lin, Y. J. (2016)’s thesis.
The numerical models are carried out to modify the code of the weakening zone, and the results are compared with the physical test results. The aim is to integrate the parameters used by the three numerical models, including the dry friction coefficient and the wet friction coefficient which is reduced by water’s influence. After number of test, we decided to adopt the value of dry friction coefficient is 0.7 and the wet friction coefficient is 0.3, and using the discrete element method to simulate at different gravity. The analysis items include the sliding process of the slope, the stacking result, the displacement of each particle and the velocity of particle.
In this study, the sliding failure mode of the dip slope will be different according to the rock structure. The dip slpoe which is interbed layer and the angle of layer is 30 degrees is "remove the toe of slope sliding mode". The dip slpoe which is interbed layer and the angle of layer is 60 degrees is "slope bulging sliding mode". The dip slpoe which layer is alteration and the angle of layer is 60 degrees is "rock fall mode".
It is hoped that the simulation results of this study will provide to the disaster prevention center to reduce the disaster caused by sliding slop.

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