基于参数时变效应的震后降雨浅层滑坡易发性研究

After Wenchuan earthquake, many slopes became loose and a lot of cracks were formed on or in them. These slopes are more easier to become shallow landslides under the condition of rainfall infiltration. According to the research progress, the vulnerability of such geological disasters will last 10 years or even longer. So, it's necessary to study the post-earthquake rainfall-induced shallow landslides susceptibility at regional-scale. However, there is still a blank in this research area. The most existing susceptibility evaluation models based on physical-process were established on the saturated soil mechanics analysis and did not consider the impact of parameters' time-dependent effect. Therefore, the project chooses Baishahe watershed of Dujiangyan City as the study area. Based on field survey and sampling, study the post-earthquake destruction mechanism under the rainfall condition with the theories supports of unsaturated soil mechanics and seepage mechanics. Using laboratory soil test, study key parameters' time-dependent effect and establish the function to show the parameters' changes with water content. And we'll also study the proportion of infiltration thickness of post-earthquake slope changes with rainfall, water content, and slope gradient by physical-model experiment. Finally, the coupling model reflecting the relationship between the rainfall infiltration and slope stability will be established with the support of GIS technology and will be used to evaluate the susceptibility of post-earthquake rainfall-induced shallow landslide of study area. The research results can provide reference and theoretical support for disaster prevention and mitigation and post-disaster construction.

汶川地震后，灾区形成大量震裂松散坡地，在降雨条件下，极易失稳，形成浅层滑坡。根据国内外研究进展，这种地质灾害的脆弱性将持续十年甚至更久。因此十分有必要进行区域尺度的震后降雨浅层滑坡易发性评价研究。本项目选择都江堰白沙河流域作为研究区，基于非饱和土力学、渗透力学等基础理论，在野外调查取样的基础上探讨震后坡地在降雨激发条件下的破坏机制；通过模型实验研究不同岩性的震裂坡地在降雨条件下滑体浸润厚度比例随有效降雨量、坡体含水率、坡角的变化规律；通过非饱和土三轴试验和渗透试验研究关键物理参数（c', φ', k）的时变效应，建立各个参数随含水率变化的函数表达式；最后利用GIS技术集成以上研究内容，建立降雨入渗和坡体稳定性的耦合方程，对区域震后降雨浅层滑坡易发性进行评价。研究成果具有理论和现实意义，可为防灾减灾和灾后重建提供参考依据和理论支持。

汶川地震后，灾区形成大量震裂松散坡地，在降雨条件下，极易失稳，形成浅层滑坡。这些滑坡为泥石路的形成和发生提供了大量的物源。根据国内外研究进展，这种地质灾害的脆弱性将持续十年甚至更久。因此十分有必要进行区域尺度的震后降雨浅层滑坡易发性评价研究。本项目选择都江堰白沙河流域作为研究区，基于非饱和土力学、渗透力学等基础理论，在野外调查取样的基础上探讨震后坡地在降雨激发条件下的破坏机制；通过降雨模型实验和渗透试验研究不同岩性的震裂坡地在降雨条件下土体的关键物理力学参数随降雨量、坡体含水量、坡度的变化规律，并建立关键参数随含水量及干密度的变化、含水量随降雨和坡度变化的函数表达式；最后利用GIS技术集成以上研究内容，建立降雨入渗和坡体稳定性的耦合方程，对区域震后降雨浅层滑坡易发性进行评价，并对可能参与泥石流活动的物源量进行了分析，进而得到了在不同降雨条件下，不稳定性斜坡的分布及泥石流危险性变化。研究成果具有理论和现实意义，可为防灾减灾和灾后重建提供参考依据和理论支持。