东南沿海残积土地区降雨诱发型滑坡预报雨强-历时曲线的影响因素分析

东南沿海山地丘陵地区每年雨季期间有大量土质滑坡发生，如何对由降雨诱发的滑坡进行预报一直都是一个热点研究课题，雨强-历时曲线（简称I-D曲线）是目前国内外常用的降雨型滑坡预报的降雨量临界值曲线。针对东南沿海地区的浅层残积土滑坡，根据相关勘察数据及资料，概化得到了该类型边坡的地质剖面及岩土层性质，然后应用Geo-Studio软件分析了边坡初始湿润条件、土体抗剪强度、饱和渗透系数、边坡坡角、残坡积土层厚度及雨型等参数对I-D曲线的影响规律。分析结果表明：残坡积土抗剪强度参数、饱和渗透系数、边坡坡角、雨型等因素对I-D曲线的影响显著，边坡安全系数降至临界值所需降雨历时随抗剪强度参数值降低、表层残积土渗透系数增加或坡角增大而减少；当雨强较小时，初始湿润条件对I-D曲线的影响显著；当雨强大于残坡积土层饱和渗透系数时，入渗量主要由渗透系数控制，边坡安全系数降至临界值所需降雨历时不随雨强增大而变化。该研究结果为I-D曲线在东南沿海残积土地区降雨诱发滑坡预警预报中的应用奠定了基础。

Parametric analyses of intensity-duration curve for predicting rainfall-induced landslides in residual soil slope in Southeastern coastal areas of China

Lots of shallow landslides in residual soil slopes are triggered by rainfall every year in Southeastern coastal area of China.Prediction of the rainfall-induced landslides is a hot research topic.Rainfall intensity-duration curve(I-D curve for short) is used commonly by previous researches to predict the landslide induced by rainfall.Firstly,the geological conditions of residual soil slopes and climate condition in Southeastern coastal areas of China are presented.Then the cross-sections and engineering properties of the residual soil slopes are presented.A finite element software,Geo-Studio,is used to study the effects of the initial moisture condition,shear strength,saturated permeability coefficient,slope angle,thickness of residual soil layer and rainfall pattern on I-D curve.Results from the parametric analyses show that shear strength,slope angle,saturated permeability coefficient and rainfall pattern influence the I-D curve significantly.With a decrease in shear strength,an increase in saturated permeability coefficient or an increase in slope angle,the rainfall duration causing a slope failure shows a decreasing trend.The influence of initial moisture condition on I-D curve is significant when rainfall intensity is lower.When rainfall intensity is larger than saturated permeability coefficient of the residual soil layer,the infiltration capacity is controlled by permeability coefficient;the rainfall duration causing a slope failure doesn’t change with the increasing of rainfall intensity.The research results can provide a basis for the application of I-D curve to predicting rainfall-induced landslides in residual soil slope in Southeastern coastal areas of China.