考虑跨尺度结构空间变异性的库岸堆积层滑坡失稳机制研究

The rock-soil mass of reservoir accumulative formation landslides have significant spatial variability in meso-scale as well as field scale, which exert great impact on identification of instability mode and evaluation of stability. The spatial variability of the two scales are not independent but inherent complicated correlated. Therefore, cross-scale spatial variability studies synthesizing the meso-scale structure and field-scale parameters are desiderated to be performed for the purpose of better understanding the instability mechanism of reservoir accumulative formation landslides. Aimed at solving two key scientific problems involving the spatial variability of rock-soil mass in reservoir accumulative formation landslide and the instability mode of reservoir accumulative formation landslide, this project selected two typical reservoir accumulative formation landslides in Three Gorges Reservoir area as the study case to perform the following studies. The engineering geological model of studied landslide case should firstly be established according to the field engineering geological condition and the evolution mechanism should be analyzed primarily. The cross-scale spatial variability is then systematically studied by nesting the meso-scale structure into the field-scale parameters, which reflects the control effect of geological process to field parameters. In this sense, the random field computation model for reservoir accumulative formation landslide can be established based on the spatial variation analysis of cross-scale spatial variability to perform stochastic finite element analysis. On this basis, studies including instability mode identification, global stability evaluation and instability process can be performed from the view of system reliability analysis, which highlighting the uncertainty and time-varying characteristics of instability mode of reservoir accumulative formation landslide under the combination effect of reservoir water fluctuation and rainfall, thus the instability mechanism will be derived. In summary, this project has the potential for providing fundamental bases and solutions for prevention and control of reservoir accumulative formation landslide in the Three Gorges Reservoir area.

库岸堆积层滑坡的岩土体结构在细观尺度和场地尺度都具有很强的空间变异性，对滑坡的失稳模式识别和稳定性评价都具有重要的影响。细观尺度结构和场地尺度参数的空间变异性相互关联，亟需将两者综合考量，开展考虑跨尺度结构空间变异性的库岸堆积层滑坡的失稳机制研究。本项目针对“库岸堆积层滑坡岩土体结构的空间变异特性”和“库岸堆积层滑坡的失稳模式”两个关键科学问题，选取三峡库区典型库岸堆积层滑坡实例，基于场地工程地质条件确立滑坡工程地质模型并探讨演化机理；将细观结构嵌套进场地参数，系统开展滑坡岩土体跨尺度结构空间变异性研究，构建滑坡随机场模型进行随机有限元分析；针对滑坡在库水位和降雨的综合作用下失稳模式的不确定性和时变性问题，从系统可靠性角度开展滑坡的失稳模式识别、整体稳定性评价和失稳过程分析相关研究，揭示滑坡的失稳机制，为库岸堆积层滑坡的防控提供理论依据。

库岸堆积层滑坡的关键地质体结构在细观尺度和场地尺度都具有很强的空间变异性，且不同尺度的空间变异性并非相互独立，亟需将两者综合考量，开展考虑跨尺度结构空间变异性的堆积层滑坡失稳机制研究。本项目聚焦“堆积层滑坡岩土体结构的空间变异特性”和“堆积层滑坡的失稳模式”两个关键科学问题，分别针对滑带主控的深厚堆积层滑坡与接触界面主控的浅薄堆积层滑坡选取典型库岸堆积层滑坡为研究对象，基于场地工程地质条件确立滑坡工程地质模型并探讨演化机理。综合考虑滑坡关键地质体在试样细观尺度的结构特征与场地宏观尺度的参数空间变异特征，基于变异函数理论提出了考虑跨尺度结构空间变异性的库岸堆积层滑坡随机场模拟方法，开展随机有限元分析。针对滑坡在库水位和降雨的综合作用下失稳模式的不确定性问题，选取不同类型的库岸堆积层滑坡，开展滑坡的失稳模式识别、整体稳定性评价和失稳过程分析相关研究，结果表明库岸堆积层滑坡的失稳模式主要分为浅表失稳、深层失稳以及复合型失稳这种类型，且三种失稳模式的概率基本相当。. 项目在以下三个方面取得创新性成果：1.基于指示克里金理论研究了不同尺度滑坡关键地质体试样的细观结构空间变异特性，结果表明细观结构不依赖于研究尺度，从而提出将这种细观尺度的空间变异性嵌套进块金值从而实现两者的综合考量。2.针对滑带主控的深厚堆积层滑坡，提出了一种基于聚类方法与混合高斯模型的期望最大化算法相结合的方法，进行堆积层滑坡不同失稳模式的概率判别，确定不同失稳模式的权重，从而实现了不同失稳模式的高精度高效率的可靠性分析。3.针对接触界面主控的浅薄堆积层滑坡，通过试验分析与理论分析确立了接触界面的场地尺度宏观形态对失稳模式的影响。. 本项目旨在从可靠性角度开展滑坡的失稳模式识别、稳定性评价与失稳过程分析相关研究，揭示滑坡的失稳机制，为库岸堆积层滑坡的防控提供关键理论依据与技术支持。