本研究旨在探討山坡地地貌特徵引發不同崩塌型態的條件，通過沙堆實驗分析崩塌型態與坡面形狀、破壞面的關係。在沙堆實驗中採用單一顆粒材料在固定點持續供砂於沙堆坡面上，使用三種不同寬度的砂箱堆積出不同形狀的坡面，並利用高速攝影機紀錄沙堆坡面崩塌的過程，藉由影像處理技術分析崩塌範圍，與座標轉換系統得出沙堆坡面的數值高程模型。為了分析坡面的穩定性，藉由理想破壞曲面(Tai et al., 2020) 建構初始崩塌時的破壞面，並討論坡面破壞前之幾何特徵 (堆積分佈、坡度與破壞面)。配合建構不同形狀的幾何坡面了解坡面形狀對安全係數的影響，當坡面的曲面最高點位置接近坡頂時，其結果顯示存在一崩塌深度使坡面呈現最不穩定的狀態。
實驗結果顯示在三種坡型下存在兩種類型的崩塌型態 (階段式崩塌和整體式崩塌)。在階段式崩塌中，其崩塌型態擁有溯源型 (retrogressing) 的特徵(Cruden & Varnes, 1996)，其破壞面由坡趾處逐漸往坡頂延伸，崩塌過程呈現多階段且連續，沙堆土體的堆積分佈主要沿著主軸 (down-slope) 方向堆積，並且初始崩塌區域的坡型呈現直坡。而整體式崩塌中，崩塌時為單一土體滑動且初始坡壞面位於坡頂處，其堆積分佈以加沙點向外延伸成一個向上凸起的橢圓形，儘管兩種崩塌型態對應不同的坡面形狀，藉由安全係數推估其最大崩塌深度皆約為主軸長度的 0.03 倍。總結而言，坡型影響不同之崩塌型態，由本研究分析沙堆幾何特徵推估可能之崩塌型態，提供一個協助評估災害之方法。

In this study, the collapse patterns and the area of displaced material are investigated through sandpile experiments. Sand grains are added gradually and continuously at a fixed point in the upstream section of the initial sand slope until the occurrence of collapses. Three widths of sandbox were assigned for constructing the initial sandpile slopes were. The topographies of pre- and post-collapse are obtained by a laser-scanning system. A CMOS-high-speed camera was employed to capture the collapse process and analyze the area of displaced material using morphological image processing. The plausible failure surface is estimated by the idealized curved surface (ICS) and the corresponding safety factor to discuss the influence of different topography. Two types of slope failure (sequential failure and single-release failure) were identified, and the width of the sandbox plays a significant role on the types of failure and the propagation of the failure surface. In the type of sequential failure, the initial displaced area is found to be on a flat slope and located near the toe of the slope. In single-release failure, the initial displacement took place on a slope with convex shape in transverse direction and located near the top of the slope. It is interesting that, for both types, the maximum failure depth is approximately 0.03 times of the length of the initial failure surface. Although more investigations are needed, these findings reveal a general hint of collapse type for estimating landslide type as well as the associate risk assessment.

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