降雨入渗下黄土边坡破坏机理及减灾技术研究

发布时间：2018-04-25 11:24

本文选题：降雨入渗 + 非饱和黄土　；参考：《西安科技大学》2015年博士论文

【摘要】：开展降雨入渗引起的黄土边坡破坏机理分析及防治技术研究具有重要的理论意义与工程应用价值。本文以典型的我国黄土边坡为背景,从降雨入渗的诱发因素入手,采用非饱和黄土渗流力学理论分析、物理模型试验和有限元数值模拟相结合的方法,研究降雨入渗下黄土边坡破坏机理,评价黄土边坡的稳定性,提出降雨入渗下黄土边坡的减灾技术。基于黄土高原地区降雨特点和边坡类型分析,给出了不同类型黄土边坡降雨入渗条件下破坏的主要影响因素,建立了黄土边坡渗流场分析模型。基于多孔介质理论和水力学理论得到了二维非饱和黄土渗流的控制方程。推导出了在降雨过程中黄土边坡内部瞬态含水率的解析解,确定了雨水入渗深度和坡体表面饱和层厚度。依据Bishop的非饱和土有效应力原理中参数?与饱和度的近似关系,建立了参数?与含水率的关系,使用GDS试验系统进行应力路径试验,确定了参数?与含水率关系式中的有关系数。依据参数?与含水率的关系,建立了降雨过程中非饱和黄土有效应力与含水率的关系式,得到了随降雨而变化的非饱和黄土边坡有效应力计算式。基于非饱和黄土有效应力原理,给出了用降雨强度、降雨历时、初始含水率和位置作为自变量的非饱和黄土抗剪强度表达式,采用简化Bishop法分析饱和-非饱和黄土边坡,得到了饱和-非饱和黄土边坡稳定性评价的安全系数计算公式。完成了降雨入渗下黄土边坡破坏机理物理试验研究。通过降雨试验获得了降雨强度和降雨历时等模型试验降雨条件数据,通过含水率和密度试验获得了模型试验黄土的初始含水率、瞬态含水率、密度和干密度,拟合了瞬态含水率、浸润锋线深度、饱和层厚度、非饱和黄土有效应力与降雨强度、降雨历时、初始含水率、位置的关系式,得到了相关参数。拟合了降雨入渗黄土边坡的渗流特性参数与干密度的关系式,简化了应用渗流理论和非饱和黄土有效应力原理所得到的瞬态含水率、有效应力计算式,简化后的计算式应用起来更加方便。通过降雨入渗黄土边坡理论分析和模型试验结果对比分析,得到了二者基本吻合的结论,验证了理论分析的正确性。基于降雨入渗黄土边坡二维渗流控制方程,使用Galerkin方法建立降雨入渗下黄土边坡渗流分析的有限元方程。以降雨入渗下黄土边坡物理模型试验得到的拟合参数为基础,对不同坡角、坡高、初始体积含水率、降雨强度、降雨历时和干密度的黄土边坡稳定性进行分析,得到了基于强度折减法的降雨入渗下黄土边坡安全系数。研究表明:随着坡角和坡高的增大,黄土边坡安全系数逐渐减小,减小的幅度越来越小,安全系数变化幅度很大。随着初始含水率和干密度的增大,黄土边坡安全系数逐渐减小,减小的幅度越来越大,安全系数变化幅度较大。随着降雨强度和降雨历时的增大,黄土边坡安全系数逐渐减小,减小的幅度越来越小,安全系数变化幅度较小。基于降雨入渗下黄土边坡破坏机理分析,针对黄土滑坡和崩塌两种灾害,提出了地表和地下排水、抗滑桩、锚索、格构锚固和重力挡墙等降雨诱发黄土滑坡防治措施,给出了危险土体锚固、危险土体支撑、危险土体清除、灌浆封闭和栅栏防护等降雨诱发黄土崩塌防治措施,得到了降雨入渗下黄土滑坡和崩塌防治措施的结构设计计算式。以海则庙黄土边坡工程为依托,依据降雨入渗下黄土滑坡判据,分析了海则庙黄土边坡破坏机理。针对海则庙黄土滑坡工程,提出了地表排水、地下排水和抗滑桩联合治理措施。验证了降雨入渗下黄土边坡破坏机理及减灾技术的合理性,结论对相关研究具有参考价值。
[Abstract]:It is of great theoretical significance and engineering application value to study the failure mechanism analysis and control technology of loess slope caused by rainfall infiltration. In this paper, based on the typical loess slope in China, starting with the inducing factors of rainfall infiltration, the seepage mechanics theory analysis of unsaturated loess, physical model test and finite element numerical simulation are adopted. A combination method is used to study the failure mechanism of loess slope under rainfall infiltration, evaluate the stability of loess slope, and put forward the disaster reduction technology of loess slope under rainfall infiltration. Based on the characteristics of rainfall and slope type in the Loess Plateau area, the main factors affecting the damage under the rainfall infiltration conditions of different types of loess slopes are given, and yellow river slope is established. The seepage field analysis model of soil slope. Based on the porous media theory and the hydraulics theory, the governing equations of the two-dimensional unsaturated loess seepage are obtained. The analytical solution of the transient water content in the Loess Slope during the rainfall process is derived, the infiltration depth of the rain water and the thickness of the saturated layer on the surface of the slope are determined. The effective stress of unsaturated soil based on the Bishop is obtained. The approximate relation between the parameters and the saturation, the relation between the parameters and the water content is established, and the stress path test is carried out by the GDS test system. The relative coefficients in the relation between the parameters and the water content are determined. According to the relation between the water content and the parameters, the relationship between the effective stress and the water content of the unsaturated loess during the rainfall process is established. Based on the principle of unsaturated loess effective stress, the expression of shear strength of unsaturated loess with rainfall intensity, rainfall duration, initial water content and position as independent variable is given. The saturated unsaturated loess slope is analyzed by simplified Bishop method and saturation is obtained. The calculation formula of the safety factor of the unsaturated loess slope stability evaluation. The physical test study on the failure mechanism of the Loess Slope under rainfall infiltration was completed. The rainfall intensity and rainfall duration were obtained by the rainfall experiment. The initial water content of the model test loess was obtained by the water content and the density test. The water content, density and dry density, fitting transient water content, infiltration frontal depth, saturation layer thickness, unsaturated loess effective stress and rainfall intensity, rainfall duration, initial water content and position relation, obtained relative parameters, fitting the relationship between the seepage characteristic parameters and dry density of the sloping loess slope, simplifying the application The transient water content obtained by seepage theory and the effective stress principle of unsaturated loess, the calculation formula of effective stress and the simplified formula are more convenient. Through the analysis of the theoretical analysis and model test results of the loess slope with rainfall infiltration, the conclusion of the two basic anastomosis is obtained, and the correctness of the theoretical analysis is verified. The two-dimensional seepage control equation of the Loess Slope under rainfall infiltration is used to establish the finite element equation of the seepage analysis of loess slope under rainfall infiltration, based on the fitting parameters obtained by the physical model test of the Loess Slope under rainfall infiltration, with different slope angle, slope height, initial volume water content, rainfall intensity, rainfall duration and dry density on the basis of Galerkin method. The stability of loess slope is analyzed, and the safety coefficient of loess slope under rainfall infiltration based on strength reduction method is obtained. The study shows that with the increase of slope angle and slope height, the safety coefficient of loess slope decreases gradually, the decreasing amplitude is smaller and smaller, the change of safety coefficient is very large. With the increase of initial water content and dry density, the Loess edge is increased. The safety coefficient of slope gradually decreases, the decrease of the safety coefficient is larger and larger. With the increase of rainfall intensity and rainfall time, the safety coefficient of loess slope decreases gradually, the decreasing amplitude is smaller and smaller. Based on the analysis of the failure mechanism of loess slope under rainfall infiltration, the Loess Landslide and the landslide and the loess landslide are analyzed. Two kinds of landslides, such as ground and underground drainage, anti slide pile, anchor cable, lattice anchorage and gravity retaining wall, are put forward to prevent and cure loess landslides induced by rainfall, such as dangerous soil anchorage, dangerous soil support, dangerous soil clearance, grouting closure and fence protection. The structural design calculation formula of landslide and collapse prevention measures. Based on the loess slope project of the Hai Hu temple, the failure mechanism of the Loess Slope in the Hai Hu temple is analyzed according to the loess landslide criterion under the rainfall infiltration. The combined treatment measures of surface drainage, underground drainage and anti slide pile are put forward for the loess landslide project of Hai Hu temple. The failure mechanism of loess slope and the rationality of disaster reduction technology are of reference value for related research.

【学位授予单位】：西安科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU444

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