入滲對非飽和邊坡淺層崩塌發生機制之研究

An Unsaturated Slope Shallow Failure Triggered by Infiltration

陳主惠(Chu-Hui Chen) ； 張守陽(Shou-Young Chang) ； 周憲德(Hsien-Ter Chou) ； 李伯亨(Bo-Heng Lee)

《中華水土保持學報》 35卷1期 (2004/03) Pp. 69-77

摘要

本研究以靜力平衡觀點探討降雨入滲對非飽和邊坡崩塌發生機制之影響，考慮非飽和土層內之負孔隙水壓，並探討濕鋒線以上之孔隙水壓影響土穩定性(Fs)，將土層破壞分為於濕鋒下降深度成正比，屬於淺層破壞。故入滲行為在有逕流水深情況下為影響非飽和邊坡崩塌之重要因子，在此情況下土層易發生淺層崩塌。

關鍵字

孔隙水壓 ； 入滲 ； 逕流水深 ； 土層穩定性 ； 淺層崩塌

並列摘要

The purpose of this study is to examine the unsaturated shallow slope failures triggered by infiltration from the perspective of static equilibrium. This study takes account of negative pore water pressure and analyzes how pore water pressure of the wetting front affects the stability of the strata. The failure in strata would be divided into two types: one is above the wetting front another is below the wetting front so as to understand the effect of infiltration on strata stability, and correspondingly to understand the effect on the initiation of possible slope shallow failure events.
To consider an unsaturated slope without groundwater, compared with the previous studies, the result reveals that the strata stability prior to rainfall is higher than those model without considering negative pore water pressure. In those cases where there is infiltrating without runoff depth, although the wetting front affects the negative pore water pressure near the surface of strata, it has little effect on the original strata stability. The main cause affecting the strata stability is the degree of slope; with the increasing of the degree of slope, the original strata will turn to be instable. Conversely, under the situations with runoff depths, strata will be destroyed above the wetting front. The depth of destruction is directly proportional to the length of the downward wetting front, which belongs to shallow failure. There fore, the infiltration process accompanied with the runoff depth is a crucial factor triggering an unsaturated soil shallow failure.

並列關鍵字

Pore water pressure ； infiltration ； runoff depth ； strata stability ； shallow failure