孔隙水壓對溪床土石流發生機制之影響

The Effect of Pore Pressure on the Occurrence of Debris Flow in Ravines

10.29417/JCSWC.199809_29(3).0004

周憲德(Hsien-Ter Chou)；廖偉民(Wei-Min Liaw)

土石流 ； 孔隙水壓 ； 液化 ； debris flow ； pore presure ； liquefaction

中華水土保持學報

29卷3期（1998 / 09 / 01）

211 - 217

繁體中文

本文以力學平衡之觀點來探討溪床之土體在不同孔隙水壓下土石流之發生條件，並與其它的臨界公式相互比較之，藉以明瞭在溪床中孔隙水壓對土石流發生機制之影響，並與堆積土體受沖刷或降雨形成的地表逕流所引起的土石流臨界條件做比較。本研究的結果顯示：不論在何種水深條件下，孔隙水壓的多寡對土石流有絕對性的影響，當土體內有超額孔隙水壓，將使土石流於較缓的溪床坡度中發生，且超額孔隙水壓愈大時，即使無地表逕流仍會引致土體液化進而發生土石流。故超額孔隙水壓實為誘發溪床土石流的一個重要因子。

Since the effect of excess pore pressure wasn't considered in pervious formula for the critical slope of the initiation of debris flow. The initiation of debris flow due to excess pore pressure on the channel bed is explored in this paper by employing theoretical analysis. A general formula considering the effect of excess pore pressure is proposed, which agrees well with other formulae while the pore pressure term is dropped. Once the excess pore pressure exists, the deposit materials on the channel bed is more prone to the occurrence of debris flow no matter where the water level is. The formula proposed in this paper agrees well with experimental data.