【作者】 刘新喜；

【导师】 唐辉明；

【作者基本信息】 中国地质大学 ， 地质工程， 2003， 博士

【摘要】 三峡库区是滑坡等地质灾害多发地带，2003年三峡水库蓄水后，库水位从135m上升至175m将导致一部分滑坡部分或全部被水淹没，库水位下降产生的渗流作用对滑坡稳定性的影响是三峡水库运营面临的一个新的重要课题。滑坡渗流和稳定性评价既是一个复杂的理论课题，也是一个重大的工程应用课题。本论文以三峡库区为背景，全面分析了库区滑坡的工程地质特征，提出了适应于渗流稳定性分析的滑坡分类；将渗流理论运用于滑坡裂隙岩体渗流研究中，并与Monte—Carlo方法相结合研究滑坡的裂隙特征。在全面系统地分析滑坡稳定性评价的基础上，将工程地质分析法、刚体极限平衡理论和有限元数值模拟来研究库水位下降对滑坡稳定性的影响。论文取得了以下主要成果包括：1．通过对三峡库区滑坡工程地质特征的研究，分析了地质环境与自然环境对滑坡发育的影响；以及地层、构造、暴雨等因素对滑坡发育的敏感性，由此建立概化的库区滑坡评价的工程地质模型。根据滑坡岩性、空间位置、裂隙特征对三峡库区滑坡进行分类，并建立了相应的滑坡渗流模型，为研究渗流作用下滑坡稳定性评价提供了新的思路。2．在库区滑坡滑动后滑体变化不大或滑坡整体滑动的情况下，运用Monte—Carlo方法对岩体进行结构面网络模拟是研究滑坡裂隙几何特性重要手段，通过结构面网络图和结构面连通图来描述滑坡裂隙网络特征，由此建立基岩滑坡的渗流模型。根据结构面网络连通图确定滑体优势结构面，并由此得到裂隙网络的渗透张量。3．通过对滑坡裂隙特征的研究，建立基岩滑坡渗流三类模型：离散网络模型、等效连续介质模型、双重介质模型。并讨论了三类模型的适应性。对于裂隙密度大、滑体面积较大时，建立等效连续介质渗流模型。通过Monte—Carlo方法求滑坡裂隙网络的渗透张量，利用有限元求解渗流方程。并以裂隙渗流理论和变形本构关系为基础，对渗流场与应力场进行耦合分析。4．系统地将离散数学图论用于滑坡裂隙岩体的网络连通性研究，并用数值矩阵将其形象地表示出来，使裂隙系统的定性描述和几何图形表示上升到数学表示。在Wittke离散模型 的基础上，以单一裂隙立方定律为基础，建立节点流量守恒、回路压力守恒方程、条形基元水压差方程联立求解。在滑体裂隙几何特征已查明、裂隙较稀疏、滑坡面积不大的情况下，建立此模型能有效地反映滑体的渗流特性，为滑坡渗流研究提供了新的方法。当研究区较大且裂隙较密集时，为整个渗流区内每条裂隙所建立的模型在计算机上就难以实现，这种情况就需划分出主干裂隙网络，细小裂隙采用渗透张量法表示，建立主干裂隙网络渗流方程与块体有限元渗流方程的耦合模型，仍会得到满意的结果。而且对于区域不大或裂隙稀疏的实际课题，直接应用本文模型将会得到理想的结果。5．对于岩体孔隙发育的情况，将裂隙作为孔隙岩块的一类边界，并通过隙壁进行水量<WP=6>交换。建立非连续介质裂隙网络模型（离散介质模型）和岩块孔隙渗流模型。所建立的双重介质水流耦合离散模型，不仅能综合地描述两类空隙系统的空间结构特征，还能真实反映出裂隙系统渗透空间的各向异性、非均匀性和非连通性以及两类系统间的水量交替特征。该模型既利于理论研究、又不失真，而且利于实际运用。6．针对库区内松散堆积层滑坡分布广、三峡水库蓄水后对这一类滑坡稳定性影响大的特点，建立了松散堆积层滑坡渗流模型。编制了库水位下降滑坡渗流场与稳定性分析计算机程序，用于对红石包Ⅲ号滑坡在库水位下降时的滑坡稳定性评价，取得如下主要成果：1）红石包Ⅲ号滑坡在水库蓄水至175m水位仍处于稳定状态。2）库水位下降对滑坡产生渗流作用，渗流场受降速的影响很大，库水位下降速度增大，渗透力也增大，滑坡稳定性降低。因此，得出滑坡失稳的临界降速。红石包Ⅲ号滑坡的临界降速为0.8m/d。3）滑坡稳定性与库水位的关系呈抛物线变化趋势。渗流浸润线开始时比较陡，经过一段时间趋于平缓。在滑坡稳定性变化上表现为开始降幅较大，经过一段时间后，滑坡稳定性达到最低点。然后滑坡稳定性逐渐升高。 4）若库水位下降速度超过临界降速，滑坡稳定性还没有跌至最低点时，滑坡就会失稳。此时对应的库水位称临界库水位。随着降速的增大，滑坡临界库水位也随之上升，且渗透系数越小，临界库水位上升越大。红石包Ⅲ号滑坡的降速为0.8m/d时，临界库水位为155m；若降速为1m/d，临界库水位为160m。5）暴雨对滑坡稳定性的影响显著，它取决于入渗补给强度、滑坡渗透系数、给水度等。研究表明，渗透系数对滑坡稳定性的影响呈抛物线变化规律。渗透系数越小，滑坡稳定性系数越低。渗透系数的降低会使滑坡库水位临界值上升。因此，低渗透性、强暴雨入渗是诱发滑坡的主要因素。红石包Ⅲ号滑坡暴雨使滑坡稳定性降低8%左右。6）通过对库水位从175m降至165m水位时滑坡的有限元模拟表明，滑坡稳定性降低10%左右，这与库水位下降时滑坡稳定性评价采用不平衡推力法得到的结果可以相互验证。更多还原

【Abstract】 There is a zone of frequent geological hazard of landslide in the Three Gorges reservoir regions. When the reservoir is in operation in 2003, the rising of reservoir water level from 135m to 175m will lead to the submerging of part or whole of the landslides. It is a new and important subject for the operation of the Three Gorges reservoir that the stability of landslide will be influenced by the seepage flow resulting from the drawdown of the reservoir. The seepage flow of landslide and the stability evaluation are a complicated theoretical and application subject.On basis of the analysis of the engineering geological characters of landslide in the Three Gorges reservoir regions, the classification of landslides is made suitable to analyze landslide stability by seepage flow. The seepage flow theory for fractured rock masses is applied to the study of the seepage flow of landslide and Monte-Carlo method is used to study the fracture character. The theory of limit equilibrium of rigid body and the numerical simulation of finite element are applied to the research on the evaluation of stability for landslide caused by the seepage flow. The main achievements are as following:1. Through the research on the engineering geological characters of landslide in the Three Gorges reservoir regions, the influence of the geological and natural environment factors upon the development of landslide, and the sensitivity of stratum, structure and rainstorm factors to the development of landslide were discussed in detail. According to the results, the general engineering geology model and the seepage flow models of landslides which are classified by lithology, space location and fracture character in the Three Gorges reservoir regions were established, which offer a new ideal for the stability evaluation of landslide by seepage flow.2. In the condition of the landslide with whole body, Monte-Carlo method, by which discontinuities network in rock is simulated, is the main way of the study on geometry features of landslide fissures. By this method, the preponderant discontinuities of landslide rock masses, network graph and connected graph of discontinuities have been gotten and the permeability tensor of the discontinuities network has been obtained. 3. According to fracture character of landslide, three kinds of seepage flow models for the bedrock landslide have been established and its adaptability has been discussed. The models include: the discrete network model, the equivalent continuum media model and the double porosity medium model. It is valid to establish the equivalent continuum media model for these landslides in condition of high dense fracture and wide area, The permeability tensor of the discontinuities network has been solved by Monte-Carlo method and the seepage flow equation by the finite element. Based on the theory of fracture seepage flow and the deformation constitutive relations, the couplings of seepage field and stress field have been analyzed.4. The graph theory in the discrete mathematics has been applied to the research on the connectivity of fissure networks and the qualitative description and geometry graph have been defined by mathematic express, the express of numerical matrix. Based on Wittke discrete model<WP=8>and the singular fissure cube theory, the node flux conservation equation, the loop pressure conservation equation and the bar unit water pressure equation have been established. This model shows its efficiency in condition of sparseness landslide fissure or a small area landslide and the geometry feature of landslide fissure ascertained and it provides a new way for the research of landslide seepage.It’s hard to establish the model of every fissure in whole seepage zone for computer simulation when the fractures are very dense. In this case, the main fissures network must be classified and the small fissures should be expressed by the method of permeability tensor. The satisfying results can be attained by establishing the seepage flow equation of main fissures network an更多还原