裂縫滲透引致淺層崩塌之臨界降雨條件分析

Threshold Conditions of Rainfall-induced Shallow Landslides with Cracks

10.29417/JCSWC.200312_34(4).0005

周憲德(Hsien-Ter Chou)

裂縫 ； 淺層崩塌 ； 入滲 ； 臨界條件 ； 降雨 ； cracks ； shallow landslides ； seepage ； threshold conditions ； rainfall

中華水土保持學報

34卷4期（2003 / 12 / 01）

347 - 352

繁體中文

本文建立一概念模式以描述裂縫滲透造成淺層崩塌之臨界降雨條件。邊坡崩塌係由總雨量及臨界降雨強度來控制。當降雨強度高於臨界降雨強度時，土體裂縫才會累積水深進而產生淺層崩塌；而當跨過此一門檻值後，土體崩壞之所需之累積降雨量隨降雨強度之增高而遞減。本模式可反應坡面裂縫之地文條件改變對臨界降雨條件之效應，並可重現前人建立之臨界降雨條件。較大規模之裂縫崩塌產生於高強度降雨之峰值附近，且隨著降雨強度增高，裂縫崩塌所需之降雨延時急速遞減。 本模式有助於評估地震對坡地災害降雨警戒值之影響，並可供坡地管理及坡地災害預警之參考。

A conceptual model is proposed in this study to describe the threshold conditions of rainfall-induced shallow landslides with cracks. Landslides occur only when the rainfall intensity exceeds the threshold value, which depends on the characteristics of cracks. The total rainfall needed to trigger the landslide decreases with increasing rainfall intensity. This model fits well previous regression curves for debris flows. Moreover, the effects of cracks on the threshold conditions can be evaluated in the present model. The rainfall intensity required for landslides to occur increases when cracks get deeper. although the rainfall duration becomes shorter. Consequently, the scenarios of large shallow landslides occur around the peaks of rainfalls.