近年來，全球暖化以及氣候變遷明顯造成極端天氣事件頻繁發生，國內外時常有邊坡破壞及土砂災害的新聞，破壞時往往在數十秒內伴隨大量的土石滑動而造成災害。本研究以市道172線42k+300處之邊坡進行研究，透過數值模型模擬172線42k+300處邊坡的崩塌行為及影響範圍，使用離散元素法(Distinct Element Method, DEM)的Three-Dimensional Distinct Element Code (3DEC)軟體建立三維邊坡模型，探討本研究區域塊體受重力滑落的崩塌歷程以及崩塌範圍，以不同弱面摩擦角對邊坡破壞程度進行敏感度分析，並將模擬成果以Unity軟體呈現 3D 可視化破壞機制和受影響區域。
研究結果顯示，以不同弱面摩擦角(10°、15°、20°)模擬皆會產生滑動，且少數零星塊體會滑落至白水溪，位於道路及下邊坡商家之觀察點具有較大位移量，道路及以下區域須提防嚴重邊坡破壞的發生，一旦發生崩塌，172線42k+300路段及周圍聚落皆會受土石崩塌影響，需要特別留意。綜合來說，市道172線42k+300處之邊坡崩塌範圍集中在172線道路以下至下邊坡地勢較突出的區域，此區域範圍為崩塌時的高度風險區，應列為防災管理之重點監測區域，透過數值模擬成果可以為當地居民提供安全評估，減少災害受損。

In recent years, global warming and climate change have led to frequent extreme weather events, causing frequent landslides and sediment-related disasters both domestically and internationally. This study focuses on the slope at Highway Tainan-172 42k+300, using numerical models to simulate the collapse behavior and impact range of the slope. A three-dimensional slope model was developed using the 3DEC software, based on the three-dimensional Discrete Element Method, to analyze the collapse process and range of the slope under gravitational forces. Sensitivity analysis was conducted by varying the joint friction angles, and the simulation results were visualized using Unity software to present the 3D failure mechanism and affected areas.
The study results indicate that simulations with different joint friction angles (10°, 15°, 20°) all resulted in sliding, with a few isolated blocks sliding into the Baishuixi River. Observation points located at businesses on the road and lower slopes exhibited significant displacement, highlighting the need to prevent severe slope failures in these areas. In the event of a collapse, Highway-172 42k+300 and surrounding settlements would be affected by landslides, warranting special attention.
Overall, the collapse range of the slope at Highway-172 42k+300 is concentrated in the area below the road to the prominent lower slope. This area is identified as a high-risk zone during landslides and should be prioritized for disaster management monitoring. The numerical simulation results can provide safety assessments for local residents, reducing disaster threats.

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