Influence of the Rainfall Parameters on the Stability of Landslide Dams

This study investigates transient seepage using a two-phase flow scheme in finite difference code, FLAC. The saturation of pore water pressure distribution and the stability of the assumed landslide dams are calculated. The safety factors of the assumed landslide dams are evaluated using the strength reduction technique. The results show that when we increase the saturated permeability of the dam materials, dam failure occurs earlier than those dams with smaller saturated permeability. When the slope angles of the dams are small, the timing of failure is slower than those dams with large slope angles. However, the durations of the failure process of dams with smaller slope angle are shorter than those of dams with larger slope angles. When the peak intensity of rainfall is higher, dams are less stable.本文以FLAC 有限差分軟體之二相流模式進行非飽和土壤暫態滲流分析，計算不同時間下所假設之堰塞壩的飽和度與孔隙水壓分布。假設之堰塞壩體穩定性則以強度折減法計算其安全係數。由結果顯示，壩體材料滲透性增加，壩體破壞之時間越早。坡度較小的堰塞壩之邊坡穩定影響時間較慢，但從穩定到滑動破壞之時間比坡角大者短。尖峰降雨強度越大，壩體越趨不穩定