隨著急遽的氣候變化，強度高或長延時的降雨事件愈加頻繁，使得山坡地區發生崩塌，引發土石流的機率更高。而為了預警山崩土石流流動行為以達減災及土沙管理目的，本研究主要是以一種理想化的曲面取代滑動類型的崩塌破壞面。一般滑動崩塌所造成的破壞曲面其主要驅動力為重力，常見形狀多為半圓管狀渠槽，且表面崎嶇。而為了找出滑動崩塌破壞面的幾何特性，以軸向(坡向down-slope)與側向(transverse)兩種曲率所控制的理想化曲面來簡化近似之，並將估算理想化曲面之方法配合Guzzetti et al. (2009)所歸納出的崩塌面積與其崩塌量體的經驗關係式，可估算出崩塌破壞面之位置及崩塌量體，以提供土石流模擬的初步條件，精進土石流預警技術。

With the global climate change, the high intensive rainfall with long duration takes place more and more often. It also increases the probability of occurrence of landslides as well as debris flows in mountainous areas. For the purpose of estimating the sediment transport or hazard mitigation, the present study aims an innovative method for estimating failure volume/surface by using an idealized curved surface to represent the basal surface by slope failure of sliding type. Generally, the driving force behind landslides is gravity. The common form of failure surface is a semicircular tubular channel, and the surface is usually rough. The geometry of the failure surface is approximated by an idealized curved surface determined by two different curvatures, in down-slope and cross-slope directions, respectively. With the help of the empirical relationship between the landslide area and volume established by Guzzetti et al. (2009), we are able to estimate the location of failure surface and relevant volume. In this way, we could provide the parameters for debris flow numerical simulation to improve the technique in forecasting and warning of landslide disasters.

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