坡面崩塌是台灣山區主要的自然災害威脅，而隨著人口的成長，台灣山區的開發也日益增加，另外也受到氣候變遷之影響，使得坡面崩塌災害發生的頻率和影響變得更加嚴重。為了解崩塌發生過程的行為與特性，本研究將現地崩塌諸多複雜之因素進行簡化，以小尺度砂堆實驗進行探討。實驗方面本研究將實驗分為兩個部份，以觀測位置作區分，分別為砂堆側面與砂堆表面的崩塌實驗，並以不同砂箱寬度進行實驗。採用單一顆粒材料，固定加砂位置，在砂堆上方持續供砂，待顆粒堆積到一定高度後，受重力作用之影響而發生崩塌，同時以高速攝影機紀錄崩塌發生之過程，將拍攝之影像透過影像處理技術進行處理並對崩塌過程之特性進分析。
在砂堆側面崩塌實驗中，拍攝結果顯示其崩塌過程呈現多個階段且連續的過程，本研究將此崩塌模式稱為階段式崩塌。而透過影像處理結果顯示其破壞面上緣形狀略成圓弧型，且破壞面明顯由坡面坡趾處逐漸往坡頂發展，利用Tai et al. (2020) 提出之理想破壞面對各時間點之破壞面進行套疊，分析破壞面的穩定性及傳遞速度，可大致了解階段式崩塌過程之特性。
在砂堆表面崩塌實驗中，不同寬度的砂箱，會造成崩塌過程的差異，依據觀察到的崩塌模式可初步分為兩類，第一類為階段式崩塌，其崩塌過程呈現多個階段且連續的過程，與砂堆側面崩塌實驗觀察到的結果類似，由坡面坡趾處逐漸往坡頂發展的過程，第二類為整體式崩塌，其崩塌過程為破壞面之整體滑動，崩塌起始之破壞面最上緣位在坡頂處，並非如同階段式崩塌位在坡趾處。

Landslide/slope failure and the subsequent mass movements result in the major natural disasters in the mountain areas in Taiwan. This study is dedicated on investigating the failure processes of a slope failure using sand pile experiments with dry sand avalanches, where sand is supplied with a tiny volume rate until failure takes place. A CMOS-high-speed camera is utilized to capture the details of a sand pile within a sandbox, aiming at the insights into the detailed behavior and characteristics of avalanches triggered by the accumulation of sand pile. Since the transient failure surfaces in the experiments are found to be curved, the idealized curved surface (ICS) developed by Tai et al. (2020) is employed to mimic the failure surface of sand avalanches. With the ICS it is possible to approximate the plausible failure surface and to estimate the associated factor of safety, yielding valuable insights into the underlying mechanism of the sequential failure process. Two types of failure were observed in experiments, where a sequential failure takes place in the narrow sandboxes (2 cm, 6 cm, and 12 cm), and the single-release failure occurs in a wider sandboxes (15 cm and 18 cm). In the sequential failure, the sand pile progressively fails and the top of the failure surface propagates along the slope upwards. In the failure type of single release, the sand mass fails as a single block. In addition, further analysis goes into the various characteristics of the corresponding avalanches, such as the geometry of the sand pile, the shapes and propagation of the failure surface, as well as the internal friction angle. The analysis on these additional parameters provides a general understanding of the characteristics of the collapse process.

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