三峡水库神女溪青石滑坡破坏机制研究

发布时间：2018-03-10 20:19

本文选题：力学参数　切入点：模型试验　出处：《重庆交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：三峡水库运行期间，库水位每年在145~175m间周期性循环升降，库水对岸坡岩土体形成了周期性浸泡，劣化库岸岩土体的抗剪强度，打破了现有岸坡的稳定性，造成库岸边坡的失稳，因此水库运行过程中岸坡稳定性变化规律及其破坏机制研究成为一个重要的研究课题。论文以三峡库区神女溪青石滑坡为背景，采用室内试验分析、数值模拟及理论分析相结合的方法，分析神女溪岸坡失稳的影响因素，并结合模型试验再现该岸坡破坏过程，通过数值模拟对其进行渗流场、位移场分析，获取该岸坡稳定性变化规律，并建立该岸坡突发性破坏机制，主要取得了以下成果：（1）现场调研选取神女溪青石滑坡不同高程处土体，采用筛分试验、X衍射光谱分析、剪切试验等方法，分析同一岸坡不同高程处土体在库水作用下粒度、矿物成分及土体力学参数的变化特性，得到了神女溪青石滑坡土体强度主要受含水量影响。（2）以神女溪青石滑坡为原型，依据相似理论，建立三峡水库神女溪岸坡破坏机制地质试验模型。拟定库水位升降变化试验工况，通过模型试验，得到岸坡不同高程处孔隙水压力数据及坡体裂缝情况，分析坡体在整个试验过程中的破坏现象，并得出孔隙水压力变化和地下水位变动是影响坡体破坏的主导诱因。（3）根据饱和-非饱和理论，结合试验模型，采用Midas/GTS数值模拟软件，模拟模型坡体渗流场变化来验证试验所得数据；同时模拟神女溪青石滑坡，获取了水库运行过程中岸坡渗流场、位移场和剪应变增量图演变趋势：水位上升阶段，岸坡孔隙水压力呈上升趋势，坡脚首先出现位移；水位下降阶段，岸坡孔隙水压力呈下降趋势，其靠近滑面处位移量逐渐增加，直至贯通。（4）应用Midas/GTS采用强度折减法获取的稳定系数与地灾规范算出的稳定系数基本吻合，，通过数值模拟及稳定性计算分析出神女溪青石岸坡在蓄水位期间，岸坡稳定性先略微增加后降低。（5）根据地貌演化特征，结合地勘资料提供的变形数据，从神女溪青石滑坡坡脚软化阶段，下部坍塌带动上部蠕动阶段，岸坡后部拉裂阶段，整体下滑阶段四个破坏过程进行分析。基于神女溪青石滑坡地质结构，将145m水位以下部位假定为应变软化区段，145m至175m区段假定为弹性区段；以突变理论、能量原理为基础，构建该岸坡破坏尖点突变力学模型，揭示该类岸坡次级滑坡突发性破坏机制。
[Abstract]:During the operation of the three Gorges Reservoir, the water level of the reservoir rises and rises periodically between 145m and 175m each year, and the reservoir water periodically immerses the rock and soil on the bank, which results in the deterioration of the shear strength of the rock and soil on the bank of the reservoir, which breaks the stability of the existing bank slope and results in the instability of the bank slope of the reservoir. Therefore, the study of slope stability and its failure mechanism has become an important research subject during the operation of the reservoir. Based on the Shennexi Qingshi landslide in the three Gorges Reservoir area, the laboratory test analysis is adopted. With the method of numerical simulation and theoretical analysis, the influencing factors of slope instability in Shennu River are analyzed, and the failure process of bank slope is reappeared by model test. The seepage field and displacement field are analyzed by numerical simulation. The variation law of the slope stability is obtained, and the sudden failure mechanism of the bank slope is established. The main achievements are as follows:. 1) the soil mass at different elevation of Qingshi landslide in Shennexi is selected, and the particle size of soil at different elevation on the same bank slope under the action of reservoir water is analyzed by means of screening test, X-ray diffraction spectrum analysis and shear test. The change characteristics of mineral composition and soil mechanical parameters show that the soil strength of Shennexi Qingshi landslide is mainly affected by water content. Based on the similarity theory, the geological test model of the failure mechanism of Shennu Creek bank slope of the three Gorges Reservoir is established based on the Shennexi Qingshi landslide, and the test conditions of the fluctuation of reservoir water level are worked out, and the model tests are carried out. The pore water pressure data at different elevation of bank slope and the fracture situation of slope body are obtained, and the failure phenomenon of slope body in the whole test process is analyzed, and it is concluded that the change of pore water pressure and the change of groundwater level are the leading inducements affecting the failure of slope body. According to the saturated-unsaturated theory, combined with the experimental model, Midas/GTS numerical simulation software is used to simulate the seepage field change of the slope body to verify the experimental data, and to simulate the Shennexi Qingshi landslide at the same time, The evolution trend of seepage field, displacement field and shear strain increment diagram of bank slope during reservoir operation is obtained: the pore water pressure of bank slope is rising in the stage of rising water level, the displacement of slope foot is first, the stage of water level decreasing, The pore water pressure on the bank slope decreases, and the displacement near the slip surface increases gradually until it is through. 4) the stability coefficient obtained by using Midas/GTS strength reduction method is basically consistent with the stability coefficient calculated by the ground disaster code. Through numerical simulation and stability calculation, it is found that the Qingshi bank slope of Shennexi is in the period of water level storage. Slope stability increased slightly and then decreased. According to the characteristics of geomorphological evolution and the deformation data provided by geological prospecting data, from the softening stage of the slope foot of Qingshi landslide in Shennexi, the upper peristaltic stage of the lower collapse and the pull crack stage at the back of the bank slope, Based on the geological structure of Qingshi landslide in Shennexi, the section below 145m water level is assumed to be elastic zone from 145m to 175m, which is based on catastrophe theory and energy principle. The sudden failure mechanism of this kind of slope secondary landslide is revealed by constructing the mechanical model of the slope failure cusp mutation.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV697.3;P642.22

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