降雨入渗条件下碎石土边坡稳定性分析

发布时间：2018-05-22 13:43

本文选题：碎石土滑坡 + 降雨入渗　；参考：《成都理工大学》2014年硕士论文

【摘要】：滑坡是一种严重的岩土体失稳现象。在所发生的各类滑坡中，碎石土滑坡是主要的滑坡类型之一，一般由坡积、残积、冲积和崩塌堆积等形成的结构松散的堆积体滑坡。降雨入渗是非饱和碎石土边坡失稳的主要诱发因素。碎石土滑坡的变形破坏是一个动态变化过程，由于滑体结构的复杂性及土体组成物质的特殊性，对其进行针对性的分析是必要的。本文针对降雨条件下碎石土边坡稳定性问题，运用饱和-非饱和渗流理论，分析不同降雨条件下土坡内渗流场的变化，利用非饱和土抗剪强度理论，结合计算出来的瞬态渗流场，对碎石土边坡的瞬态稳定性进行分析。本文研究的主要内容及成果包括： 1．基于非饱和碎石土特性及降雨条件下的饱和-非饱和渗流基本理论，分析降雨入渗的影响因素。采用室内试验和二维有限元方法，进行边坡的降雨入渗分析。土-水特征曲线（SWCC）是分析非饱和土的强度和变形特性的关键。本文利用压力板仪，进行了三种不同级配土样的脱水过程的土-水特征曲线试验。试验结果表明，级配对土-水特征曲线的陡缓变化趋势影响显著，颗粒粗、级配差的土体土-水特征曲线较陡。在室内进行降雨型滑坡的物理模拟试验，根据预先埋设的体积含水率传感器，测得不同降雨强度下，坡体内不同深度的含水率变化情况。根据实验结果，探讨了不同降雨强度及同一降雨强度不同深度范围内体积含水率的变化规律。运用VADOSE/W软件，建立了降雨型边坡稳定性的渗流有限元分析模型，给出了降雨入渗有限元分析的实施步骤。结合算例，探讨了降雨强度、降雨持时、前期降雨、渗透系数和各向异性对渗流场的影响。 2．渗流场与应力场是相互影响的，渗流场改变土体的力学性质，土体应力作用直接影响着渗透系数。从渗流-应力耦合理论出发，阐述了渗流-应力耦合基本方程，建立非饱和边坡的渗流-应力耦合模型。结合算例，，采用有限元方法计算了降雨强度、降雨持时、前期降雨、渗透系数和各向异性对渗流场的影响，并将其结果与非耦合计算结果进行对比分析。 3．介绍了降雨入渗对边坡稳定性影响的机理及降雨入渗条件下边坡稳定性分析方法。运用ABAQUS有限元软件计算在渗流-应力耦合计算中所得到的暂态孔隙水压力分布，用于土坡稳定性分析，得出相应情况下土坡稳定系数的变化规律。
[Abstract]:Landslide is a serious rock and soil instability phenomenon. Among all kinds of landslides, macadam landslide is one of the main landslide types, which is usually composed of slope product, residual product, alluvium and collapse accumulation. Rainfall infiltration is the main inducing factor of unsaturated gravel slope instability. The deformation and failure of macadam landslide is a dynamic change process. Due to the complexity of sliding body structure and the particularity of soil composition, it is necessary to analyze it pertinently. Aiming at the stability of gravel slope under rainfall condition, this paper analyzes the variation of seepage field in soil slope under different rainfall conditions by using saturated-unsaturated seepage theory, and applies the theory of shear strength of unsaturated soil to analyze the variation of seepage field in slope under different rainfall conditions. Combined with the calculated transient seepage field, the transient stability of gravel slope is analyzed. The main contents and achievements of this paper are as follows: 1. Based on the characteristic of unsaturated gravel soil and the basic theory of saturated-unsaturated seepage under rainfall condition, the influencing factors of rainfall infiltration are analyzed. The rainfall infiltration analysis of slope is carried out by using indoor test and two-dimensional finite element method. Soil-water characteristic curve (SWCC) is the key to analyze the strength and deformation characteristics of unsaturated soil. In this paper, the soil-water characteristic curves of the dehydration process of three different gradation soil samples have been tested by using a pressure plate instrument. The results show that the gradation has a significant effect on the steepness of soil-water characteristic curve, and the soil-water characteristic curve with coarse particles and different gradation is steeper. The physical simulation test of rainfall landslide was carried out in the laboratory. According to the volume water content sensor embedded in advance, the variation of water content in different depth of slope was measured under different rainfall intensity. Based on the experimental results, the variation of volume water content in the range of different rainfall intensity and the same rainfall intensity and different depth is discussed. Using VADOSE/W software, the seepage finite element analysis model of rainfall slope stability is established, and the implementing steps of rainfall infiltration finite element analysis are given. The effects of rainfall intensity, rainfall duration, early rainfall, permeability coefficient and anisotropy on seepage field are discussed. 2. The seepage field and stress field affect each other. The seepage field changes the mechanical properties of the soil, and the stress of the soil directly affects the permeability coefficient. Based on the theory of seepage and stress coupling, the basic equation of seepage stress coupling is expounded, and the seepage stress coupling model of unsaturated slope is established. The effects of rainfall intensity, rainfall duration, early rainfall, permeability coefficient and anisotropy on seepage field are calculated by using finite element method, and the results are compared with those of uncoupled calculation. 3. The influence mechanism of rainfall infiltration on slope stability and the analysis method of slope stability under rainfall infiltration are introduced. The transient pore water pressure distribution obtained by using ABAQUS finite element software in the seepage stress coupling calculation is used to analyze the stability of the soil slope and the variation law of the stability coefficient of the soil slope under the corresponding conditions is obtained.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU43;P642.22

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