非饱和—饱和状态变化条件下土质边坡稳定性分析
发布时间：2018-11-23 18:40
【摘要】：非饱和土问题得到越来越多的关注,其中处于非饱和状态下的边坡安全问题是亟待解决的问题。非饱和土边坡失稳不仅对人身财产造成巨大损失同时也对人类的安全造成严重的危害。降雨等原因会引起土体含水量的改变进而导致边坡土体的抗剪强度的改变,影响到边坡的稳定状态。研究非饱和-饱和状态变化对边坡稳定性的影响具有重要的工程意义。非饱和土中含水率、粘聚力、基质吸力和内摩擦角是相互关联的重要物理力学参数。非饱和土内部赋存的基质吸力是其不同于饱和土的本质原因,当含水量发生变化时,非饱和土的基质吸力相应变化,不同深度的基质吸力分布情况也随着改变;作为非饱和状态下土体抗剪强度的重要组成部分,基质吸力的改变直接影响着土体结构的抗剪强度,决定着土质边坡的稳定性。根据土骨架应力状态下饱和土与非饱和土抗剪强度的统一公式,结合基质吸力与土-水特征曲线(SWCC),对非饱和土体的抗剪强度公式进行变换,获得能够反映土体非饱和-饱和状态变化与抗剪强度相关联的参数—等效粘聚力。依据非饱和-饱和状态变化条件下,土体含水量、基质吸力分布不同,编制计算程序对边坡进行等效粘聚力的赋值,进行初始平衡、流体平衡、等效粘聚力重新分布和安全系数计算,分析非饱和-饱和状态变化下土质边坡的稳定性。通过模拟不同入渗深度条件下边坡数值计算,对不同土层孔隙水压力、基质吸力分布、剪应变增量云图和安全系数等数据分析,研究入渗导致的土体从非饱和状态到饱和状态变化过程中边坡的稳定性变化规律,分析边坡土体状态变化过程中,等效粘聚力的变化对于边坡安全系数的影响以及边坡滑移面的变化情况。基于数值计算结果,得到非饱和-饱和状态变化条件下,土质边坡稳定性变化规律与分析含水量、基质吸力、等效粘聚力之间的内在联系;进一步获得土体由非饱和状态向饱和状态转变过程中边坡安全系数的变化规律,为实际工程背景下的边坡失稳灾害防治和优化设计与施工方案提供理论指导和技术支持。
[Abstract]:More and more attention has been paid to the problem of unsaturated soil, in which slope safety in unsaturated state is an urgent problem to be solved. The instability of unsaturated soil slope not only causes huge loss of life and property, but also causes serious harm to human safety. Rainfall and other reasons will cause the change of soil moisture content and the shear strength of the slope, which will affect the stability of the slope. It is of great engineering significance to study the influence of unsaturated-saturated state on slope stability. Moisture content, cohesion, matrix suction and internal friction angle are important physical and mechanical parameters related to each other in unsaturated soil. The internal matrix suction of unsaturated soil is the essential reason which is different from saturated soil. When the water content changes, the matrix suction of unsaturated soil changes correspondingly, and the distribution of matrix suction in different depth also changes with the change of water content. As an important part of soil shear strength in unsaturated state, the change of matrix suction directly affects the shear strength of soil structure and determines the stability of soil slope. According to the unified formula of shear strength of saturated soil and unsaturated soil under the state of soil skeleton stress, combined with matrix suction and soil-water characteristic curve (SWCC), the formula of shear strength of unsaturated soil is transformed. The equivalent cohesive force, which can reflect the variation of unsaturated-saturated state and shear strength of soil, is obtained. According to the different distribution of soil water content and matrix suction under the condition of unsaturated and saturated state, the calculation program is compiled to assign the equivalent cohesive force to the slope, to carry out the initial equilibrium and the fluid balance. The stability of soil slope under unsaturated-saturated state is analyzed by redistribution of equivalent cohesive force and calculation of safety factor. By simulating the slope numerical calculation under different infiltration depth, the data of pore water pressure, matrix suction distribution, shear strain increment cloud diagram and safety factor of different soil layers are analyzed. The variation law of slope stability caused by infiltration from unsaturated state to saturated state is studied, and the process of slope soil state change is analyzed. The influence of the equivalent cohesive force on the slope safety factor and the variation of slope slip surface. Based on the numerical results, the internal relations between the stability of soil slope and the analysis of water content, matrix suction and equivalent cohesive force are obtained under the condition of unsaturated and saturated state. Furthermore, the variation law of slope safety factor in the process of changing from unsaturated state to saturated state is obtained, which provides theoretical guidance and technical support for slope instability disaster prevention and optimization design and construction scheme under the background of practical engineering.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU43
本文编号：2352392
[Abstract]:More and more attention has been paid to the problem of unsaturated soil, in which slope safety in unsaturated state is an urgent problem to be solved. The instability of unsaturated soil slope not only causes huge loss of life and property, but also causes serious harm to human safety. Rainfall and other reasons will cause the change of soil moisture content and the shear strength of the slope, which will affect the stability of the slope. It is of great engineering significance to study the influence of unsaturated-saturated state on slope stability. Moisture content, cohesion, matrix suction and internal friction angle are important physical and mechanical parameters related to each other in unsaturated soil. The internal matrix suction of unsaturated soil is the essential reason which is different from saturated soil. When the water content changes, the matrix suction of unsaturated soil changes correspondingly, and the distribution of matrix suction in different depth also changes with the change of water content. As an important part of soil shear strength in unsaturated state, the change of matrix suction directly affects the shear strength of soil structure and determines the stability of soil slope. According to the unified formula of shear strength of saturated soil and unsaturated soil under the state of soil skeleton stress, combined with matrix suction and soil-water characteristic curve (SWCC), the formula of shear strength of unsaturated soil is transformed. The equivalent cohesive force, which can reflect the variation of unsaturated-saturated state and shear strength of soil, is obtained. According to the different distribution of soil water content and matrix suction under the condition of unsaturated and saturated state, the calculation program is compiled to assign the equivalent cohesive force to the slope, to carry out the initial equilibrium and the fluid balance. The stability of soil slope under unsaturated-saturated state is analyzed by redistribution of equivalent cohesive force and calculation of safety factor. By simulating the slope numerical calculation under different infiltration depth, the data of pore water pressure, matrix suction distribution, shear strain increment cloud diagram and safety factor of different soil layers are analyzed. The variation law of slope stability caused by infiltration from unsaturated state to saturated state is studied, and the process of slope soil state change is analyzed. The influence of the equivalent cohesive force on the slope safety factor and the variation of slope slip surface. Based on the numerical results, the internal relations between the stability of soil slope and the analysis of water content, matrix suction and equivalent cohesive force are obtained under the condition of unsaturated and saturated state. Furthermore, the variation law of slope safety factor in the process of changing from unsaturated state to saturated state is obtained, which provides theoretical guidance and technical support for slope instability disaster prevention and optimization design and construction scheme under the background of practical engineering.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU43
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