台灣地質狀況不佳，邊坡破壞已成為台灣主要的地質災害之一，對於邊坡穩定之問題，傳統上以極限平衡法為目前最常被使用的分析方法，其假設此類問題係由應力控制而可忽略大地材料變形性的影響，但邊坡穩定性實際上仍須考慮材料之變形性與張力強度等影響。變形分析法是一基於連體力學原則的分析方法，而根據變形分析理論為基礎之數值分析方法主要考慮材料的應力-應變性質，其分析時可考慮較複雜的材料彈塑性行為與不同破壞準則，可藉以計算出材料之應力及應變，目前已廣泛的使用於大地工程分析。

　　本文以變形分析法作為邊坡穩定數值分析之理論基礎，並採用剪力強度折減法(shear strength reduction technique)之觀念來訂定合理的邊坡安全係數並判斷可能破壞滑動面位置，並以變形分析法與極限平衡法之分析結果進行討論。針對邊坡之不同坡度角、彈性模數和不同之材料破壞準則以探討邊坡之穩定性，本研究分析可得以下之結果：當坡角增加時，安全係數隨之下降，此與極限平衡法所得之結果一致；本研究方法所定出之滑動帶涵蓋整個Bishop簡化法及Janbu簡化法之滑動面，且發展趨勢較為平緩，並可看出邊坡之破壞由坡趾至坡頂漸進破壞之過程；材料之彈性模數對於邊坡整體之穩定似乎無太大之影響；而研究顯示材料破壞準則之選擇將影響邊坡安全係數之結果。

　Because of its inferior geological conditions and environmental factors, geological hazards like landslides are of great concern in Taiwan. The stability of soil slopes which mainly involves factor of safety is analyzed by the limit equilibrium method (LEM) and the deformation analysis method. The objective of this thesis is to investigate the stability of soil slope problem by using a numerical analysis procedure combining with the deformation analysis method, in which the stress-strain character of soil mass can be considered. The focus of this thesis is on the stability of soil slopes, in terms of factor of safety (FS) and failure surface location. Determination of the FS in numerical analysis method is mainly based on the concept of reduction in shear strength, and the corresponding failure surface is fairly found from the shear strain rate contour. It should be noticed that the critical slip surface is not an unique line. A narrow yielding zone was developed when the slope started to fail and any slip surface passing through the yield zone could be the failure surface. The main advantage of the proposed method for slope stability analysis over the traditional limit equilibrium method is that no assumption needs to be made in advance about the slice side forces, the location or shape of the slip surface. The factor of safety obtained by the proposed procedure is in a good agreement with that determined by the Bishop’s and Janbu’s methods. However, the proposed procedure can provide the designers a more solidly based concept in slope stability analysis.

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