簡易公式研究不同滲流方向對邊坡和土石流力學之影響

Investigating the Effect of Various Seepage Directions on the Mechanism of Slope and Debris Flows by Using Simplified Formulas

10.29417/JCSWC.201212_43(4).0001

蕭達鴻(Darn-Horng Hsiao)

邊坡穩定 ； 土石流 ； 滲流 ； 簡易公式 ； Slope stability ； debris flow ； seepage ； simplified formulas

中華水土保持學報

43卷4期（2012 / 12 / 01）

285 - 292

繁體中文

本文利用土壤重力和滲流力分析滲流方向對於邊坡水力坡降、安全係數和滑動面水壓力之影響，對於四種滲流方向包括水平滲流、平行邊坡滲流、垂直滲流和垂直邊坡滲流等進行討論，結果發現水平滲流安全係數最低是因其較高孔隙水壓力所致，本文也舉一案例說明滲流對有限邊坡安全性之影響。至於土石流滲流方向對於土石流趨動角度亦有顯著影響，結果並與Takahashi公式（1977、1982）進行討論與比較。

Firstly, the soil gravity force and seepage force are used to study the effect of seepage direction on the slope hydraulic gradient, safety factor and the excess pore water pressure existing on the failure plane. Four seepage directions including horizontal seepage, parallel to slope surface, vertical seepage and perpendicular to slope surface are considered. A series of related formulas is developed. It is found that the safety factor of horizontal seepage direction is lower due to the pore water pressure generated within the failure plane. In addition, a case study on the finite slope is analyzed to describe the importance of seepage direction. The initiated driving angle of debris flow is also affected significantly by seepage direction, especially when the seepage direction is near the slope angle. Finally, the results are compared with those found by Takahashi (1977, 1982).