暴雨耦合库水位变动作用下顺层岩质边坡溃曲破坏机理研究

The three gorges reservoir area is not only a high incidence area of bedding rock landslide but also a concentration area of local rainstorm. Under the coupling action of the flood season rainstorm and the fluctuation of reservoir water level, many large-scale bedding bedrock landslides have been formed. The first characteristic is that the seepage and stress fields of the slope are changed by the coupling action of the infiltration path from the top to the bottom of the rainstorm and the dynamic and hydrostatic pressure caused by the change of reservoir water level. Second, along the bedding slope along the slippery soft layer creep, the upper shear layer tension crack expansion, the lower slope foot compression buckling. The risk of these landslides is difficult to assess and predict. This project aims at studying the buckling failure mechanism of bedding rockslide under the coupling effect of reservoir water level fluctuation and intense fall, in order to achieve (1) the bedding rock slope seepage mechanics model is established on the basis of revealing the rain infiltration reservoir water fluctuation and the coupling effect on deformation of bedding rock slope, the quantitative reflection of rainfall and reservoir water in the slope instability of performance, to deepen the understanding of the mechanism of slope deformation characteristics and behavior;(2) on the premise of considering the strength change of weak interlayer, the evolution model of initial deformation, progressive failure and buckling instability of bedding slope rock mass is constructed, and the theoretical calculation method of stability of such slope is established, so as to improve the theoretical research level of bedding slope instability mechanism and promote the effective solution of disaster prevention and reduction in the reservoir area.

三峡库区是我国顺层岩质滑坡的高发区，也是我国局地暴雨的集中区。在汛期暴雨和库水位变化的耦合作用下，形成了多起大型顺层基岩滑坡灾害。其特征一是暴雨由上到下的入渗路径与库水位变动引起的动、静水压耦合作用，改变了坡体的渗流场和应力场；二是顺层边坡沿易滑软层蠕变，上部切层张拉裂隙扩展，下部坡脚挤压溃曲，其滑坡发生的危险程度难以评估预测。本项目拟在考虑暴雨与库水位耦合作用下，开展库区典型涉水顺层岩质边坡的失稳机理与成灾风险研究，以期达到（1）在建立顺层岩质边坡渗流力学模型的基础上，揭示暴雨入渗与库水变动耦合对顺层岩质边坡变形的影响，量化反映降水与库水在边坡失稳中的表现，加深对边坡变形特性与行为机制的认识；（2）在考虑软弱夹层强度变化的前提下，构建顺层边坡岩体初始变形-渐进破坏-溃曲失稳的演化模型，确立该类边坡的稳定性理论计算方法，提升顺层坡失稳机理的理论研究水平，促进库区防灾减灾问题的有效解决。

三峡库区地处川东弧形褶皱带，发育三叠系、侏罗系泥岩、页岩、砂岩等软硬相间的地层结构，控制着顺层滑坡的形成。在汛期暴雨和库水位周期变动的耦合作用下，形成了多起大型顺层基岩滑坡。具有暴雨联合库水位变化特征的顺层滑坡灾害主要有两个特点：一是暴雨由上到下的入渗路径与库水位变动引起的动、静水压耦合作用，改变了坡体的渗流场和应力场；二是顺层边坡在自重作用下，沿易滑软层蠕变滑移，上部切层张拉裂隙扩展，下部坡脚被动挤压弯曲–隆起–溃曲，增加了滑坡危险评估的难度与精度。因此，亟待开展这类顺层滑坡的变形失稳机理，把握致灾因素与破坏规律，对库区科学防灾减灾具有重要的现实意义。. 本研究在考虑暴雨与库水位耦合效应的作用下，开展库区典型涉水顺层岩质边坡的失稳机理与成灾风险研究，取得如下成果：1.建立了新的涉水顺层岩质边坡水力分布模型；2.基于压杆理论，提出了库水位变动作用下顺层岩质边坡的稳定性计算方法；3.提出了考虑后缘裂隙水作用下顺层岩质边坡溃屈破坏的失稳判据与临界滑动深度Tcr计算方法；4.实现了库水位变动叠加暴雨作用下顺层岩质边坡弯曲-溃屈破坏全过程的数值模拟表达。. 从而实现了以下两个研究目标：1.在建立顺层岩质边坡渗流力学模型的基础上，揭示暴雨入渗与库水变动耦合对顺层岩质边坡变形的影响，量化反映降水与库水在边坡失稳中的表现，加深对边坡变形特性与行为机制的认识。2.在考虑软弱夹层强度变化的前提下，构建顺层边坡岩体初始变形-渐进破坏-溃曲失稳的演化模型，确立该类边坡的稳定性理论计算方法，提升顺层边坡失稳机理的理论研究水平，促进库区防灾减灾问题的有效解决。