降雨条件下边坡入渗及稳定性的影响因子分析

发布时间：2018-06-15 10:33

本文选题：降雨 + 入渗　；参考：《浙江大学》2014年硕士论文

【摘要】：近年来,降雨入渗导致边坡失稳的情况越来越多,这是由于雨水入渗后破坏了边坡的应力平衡体系。降雨对边坡产生作用的机理主要在两方面：一是降雨动能外部的作用,二是降雨入渗后坡体内部产生的有关作用。以前只注重前者,对于后者研究较少,但这种作用往往是非常重要的。同时,降雨入渗和边坡破坏是一个不断随时间持续变化的过程,其受土体类型及性质、雨型及雨强、边坡构造形状、地下水及人类工程活动的影响。针对这一情况,本文从外在因素(降雨形式、初始含水率、气阻分层)和内在因素(边坡倾角、斜边形状、饱和导水率)的角度对边坡入渗特性和稳定性的影响进行了详细分析。首先介绍了非饱和土的概念及其入渗理论,分别阐述了Green-Ampt模型、Horton模型、Philip模型、Kostiakov模型的基本假设和使用条件,重点介绍了Bishop和Fredlund非饱和土抗剪强度公式以及两者之间的区别,之后阐述了非饱和土稳定性分析特点和极限平衡分析方法。本文侧重探讨了变雨强强度下边坡入渗特性与常降雨强度的差异,以及饱和导水率、土壤类型在变雨强下的敏感性分析；推导了初始含水率线性和任意函数分布下的湿润锋随时间的变化关系,并将线性分布下的函数关系带入边坡安全系数公式中进行了稳定性分析；讨论了分层假定的入渗量修正和气阻作用Green-Ampt模型的入渗率修正,并运用其修正结果分析了入渗时间和湿润锋深度的变化关系：分析了积水条件和降雨条件下倾角对边坡入渗和稳定的敏感性,将湿润锋和时间变化关系无量纲化,并应用于边坡安全性分析中；求解了梯田在灌溉条件下边坡潜在滑裂面的位置,并与斜坡同一时刻下的安全性作了对比；假设了饱和导水率沿竖向指数、线性、幂次变异情况下,入渗率的表达式及湿润锋和时间的变化关系,并分析了入渗偏差较小的指数和幂次变异下的边坡安全系数。研究表明,不管外在因素(降雨形式、初始含水率、气阻分层)还是内在因素(边坡倾角、斜边形状、饱和导水率)对入渗和边坡稳定都有明显影响,加强这方面的分析对了解边坡入渗内部运动和准确把握边坡失稳有重要意义,从而适时采取有效的防护措施。
[Abstract]:In recent years, more and more slope instability is caused by rainfall infiltration, which is due to the failure of the slope stress balance system after Rain Water infiltration. The mechanism of rainfall acting on slope mainly lies in two aspects: one is the external effect of rainfall kinetic energy, the other is the related effect of slope body after rainfall infiltration. Previously only the former, for the latter less research, but this role is often very important. At the same time, rainfall infiltration and slope failure is a process of continuous change with time, which is influenced by soil type and property, rain type and rain intensity, slope structure shape, groundwater and human engineering activities. In this paper, the external factors (rainfall form, initial moisture content, air resistance stratification) and internal factors (slope inclination, slope shape) and internal factors (slope angle, slope shape) are analyzed in this paper. The influence of saturated water conductivity on slope infiltration characteristics and stability is analyzed in detail. Firstly, the concept of unsaturated soil and its infiltration theory are introduced. The basic assumptions and application conditions of the Horton model and the Philip model and the Kostiakov model of the Green-Ampt model are expounded respectively. The shear strength formulas of Bishop and Fredlund unsaturated soils and the difference between them are introduced. Then, the characteristics of unsaturated soil stability analysis and limit equilibrium analysis method are described. In this paper, the difference between the infiltration characteristics of slope and the intensity of constant rainfall, and the sensitivity analysis of saturated water conductivity and soil type under variable rainfall intensity are discussed. The variation of wetting front with time under linear and arbitrary function distribution of initial moisture content is deduced, and the function relation under linear distribution is introduced into the formula of safety factor of slope for stability analysis. The infiltration rate correction of the stratified assumption and the gas resistance Green-Ampt model is discussed. The relationship between infiltration time and depth of wetting front is analyzed by using the modified results. The sensitivity of dip angle to slope infiltration and stability is analyzed under the condition of water accumulation and rainfall, and the relationship between wetting front and time is dimensionless. It is applied to slope safety analysis, the location of potential slip surface of terrace under irrigation condition is solved, and compared with the safety of slope at the same time, the saturated water conductivity is assumed to be linear along the vertical exponent. Under the condition of power variation, the expression of infiltration rate and the relation between wetting front and time are analyzed, and the slope safety factor under the condition of low infiltration deviation and power variation is analyzed. The results show that whether external factors (rainfall form, initial moisture content, air resistance stratification) or internal factors (slope angle, slope shape, saturated water conductivity) have a significant impact on infiltration and slope stability. Strengthening the analysis in this respect is of great significance to understand the internal movement of the slope infiltration and accurately grasp the slope instability, so as to take effective protection measures at the right time.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU43

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