三峡库区典型顺向岸坡库水与降雨联合作用失稳观测与理论解析

In order to establish the geological models of deformation and failure of the typical translational bank slopes in the Three Gorges Reservior, the deformation and failure characteristics of these bank slopes triggered by the combining effect of reservoir water and rainfall are studied in detail with field investigation and ILRIS-HD-ER laser scanner methods, and so on. The main mineral components and the microstructure changes of the incompetent beds and important bedding surfaces within the water level variation zone under the combining effect of reservoir water and rainfall are observed and anaylsed with the methods of scanning electron micrograph, X-ray diffraction analysis and infrared ray analysis. Considering the combining effect of reservoir water and rainfall, shear tests are conducted on the incompetent beds and important bedding surfaces within the water level variation zone to research the softening mechanism of the shear strength. In order to study the rainfall infiltration process and the characteristics of underground water flow, the rainfall infiltration, underground water table, stress and displacement of the typical translational bank slopes are monitored using real-time monitoring system. Artificial rainfall tests, permeability tests and soil-water characteristic curve tests are performed on the typical translational bank slope soils. According to the monitoring and testing data mentioned above, the rainfall infiltration mathematical models and seepage-stress coupled mathematical models are built. Based on the existing international common software, new numerical simulation software are developed to simulate the combining effect of reservoir water and rainfall. The numerical simulation are performed on the typical translational bank slopes in the Three Gorges Reservoir with the developed software to reveal the failure mechanism and process of the translational bank slopes under the combining effect of the reservoir water and rainfall. Therefore, scientific theroies and effective methods can be discovered to prevention and mitigation of the translational bank slope instability in the Three Gorges Reservoir.

采用野外调研与三维激光扫描等方法，研究三峡库区典型顺向岸坡在库水与降雨联合作用下变形破坏特征，建立典型顺向岸坡变形破坏的地质模型。使用扫描电镜、X粉晶衍射与红外光谱分析等研究消落带软弱岩层与关键岩层面结构、构造与物质成分的变化规律；考虑水的浸泡与库水位升降作用，对消落带软弱岩层与关键岩层面进行剪切实验，探讨消落带软弱岩层与关键岩层面抗剪强度弱化机理。对典型顺向岸坡降雨入渗、地下水位、应力与位移进行系统的实时监测，再结合人工降雨模拟试验、渗透试验与水分特征曲线试验，探讨顺向岸坡降雨入渗过程与地下水运动特征，建立库水与降雨联合作用下降雨入渗数学模型与裂隙岩体渗流－应力耦合数学模型。在现有国际通用软件的基础上研发库水与降雨联合诱发作用的数值模拟软件，对三峡库区顺向岸坡进行客观真实的数值模拟，揭示三峡库区顺向岸坡在库水与降雨联合作用下的失稳致灾机理与过程，为顺向岸坡失稳防灾减灾提供科学理论依据。

采用野外调研与实时监测等方法，研究三峡库区典型顺向岸坡在库水与降雨联合作用下变形破坏特征，建立典型顺向岸坡变形破坏的地质模型。结果表明：三峡库区涉水顺层滑坡是在长江的深切作用与长期的重力作用下，岩层顺着软弱夹层、土层与基岩面发生蠕滑变形形成，可能具有多层滑动面。.使用扫描电镜、X 粉晶衍射与红外光谱分析等研究消落带软弱岩层与关键岩层面结构、构造与物质成分的变化规律；考虑水的浸泡与库水位升降作用，对消落带软弱岩层与关键岩层面进行剪切实验，探讨消落带软弱岩层与关键岩层面抗剪强度弱化机理。结果表明：消落带软岩由于库水涨落经受反复的干湿循环作用，造成其微观结构发生改变，裂纹迅速扩展，抗剪强度大大降低。.对三峡库区典型顺向岸坡降雨入渗、地下水位、应力与位移进行系统的实时监测，根据渗透试验与水分特征曲线试验，探讨了顺向岸坡降雨入渗过程与地下水运动特征，建立了三峡库区顺向岸坡在库水与降雨联合作用下降雨入渗数学模型与裂隙岩体渗流－应力耦合数学模型。考虑库水与降雨联合作用，分别采用Geo-Studio、Flac3D和UDEC等软件对三峡库区典型顺向岸坡进行了渗流-应力耦合作用数值模拟研究。结果表明：库水位升降改变了岸坡前缘的地下水位，降雨则对岸坡浅表层岩土体的饱和度影响巨大，在两者联合作用下岸坡的剪应变、位移量及塑性区范围显著增大，从而导致了顺向岸坡的变形破坏甚至失稳。