多雨型下不同边坡稳定性的数值分析
发布时间：2019-03-27 08:01
【摘要】：研究降雨入渗对边坡的稳定具有重要的意义，岩土界对降雨诱发滑坡机制的探讨逐渐增多，但多考虑的是降雨强度、降雨延时以及地质条件等方面，常常忽视了降雨雨型的影响，本文通过Geo-studio中的Seep/w和Slope/w模块分别模拟降雨入渗和边坡稳定，分析不同降雨条件下，边坡安全系数随时间变化的关系。以下为主要研究内容和结论： 1.本文首先设置了高、中、低不同的渗透系数，针对降雨强度与渗透性的关系做一系列的模拟，分别探讨它们在不同降雨强度下对边坡稳定的影响。分析得到了：降雨强度会影响边坡的稳定性，但它的影响存在一个极限值，而这个极限值由饱和渗透系数决定。所以我们在求取导致边坡失稳的临界雨强时可通过土壤的渗透性作为推估条件。 2.在前人的研究的基础上，提出了：总降雨量一定，降雨过程中雨强峰值按出现的时间先后顺序分类的七种雨型，通过数值模拟分别探究各雨型对边坡稳定的影响，结果表明降雨总量一定时雨强峰值出现的时间先后顺序影响着边坡稳定，降雨过程中越先出现雨强峰值的，安全系数越早降低，而雨强峰值较后出现的，，尽管安全系数较晚降低，但下降幅度较大，即较晚出现雨强峰值的雨型对边坡更为不利。 3.对均匀雨型在渗透系数k=0.001cm/s和k=0.1cm/s的情况下，分析前期降雨强度对边坡稳定的影响，得到该两种渗透系数使边坡达到不稳定的前期降雨量分别为233mm和120mm。结果表明：仅仅在前期降雨量达到某一定值时，边坡的安全系数才会降低，前期降雨会提前导致边坡达到濒临破坏的状态，若之后再遇到较大强度的降雨时，则极有可能发生边坡失稳。 4.针对均匀雨型，改变其中某一或几个影响因素，通过三个案例分别模拟不同边坡土体类型、坡角、坡高、地下水位等边坡性质在不同降雨强度下对边坡稳定的影响，从而确定不同性质和类型的边坡影响因素的影响水平，结果得到，坡角、坡高越大边坡越不稳定，降雨前的安全系数值由边坡岩土材料参数决定，降雨发生后，材料饱和渗透系数、降雨强度为决定边坡稳定的重要因素，其中降雨强度越大，安全系数值下降越快，而材料渗透系数决定了雨水对边坡稳定的影响程度，地下水位方面，得出降雨强度较高时，由于受到强降雨入渗的影响地下水位面变化较大，因此地下水位深度在强降雨的情况下影响较不明显。
[Abstract]:The study of rainfall infiltration is of great significance to the stability of slope. The discussion on the mechanism of rainfall-induced landslides is gradually increasing in the rock-soil boundary, but the rainfall intensity, rainfall delay and geological conditions are considered in many aspects, such as rainfall intensity, rainfall delay and geological conditions, etc. The influence of rainfall pattern is often ignored. In this paper, Seep/w and Slope/w modules in Geo-studio are used to simulate rainfall infiltration and slope stability respectively, and the relationship between slope safety factor and time under different rainfall conditions is analyzed. The following are the main contents and conclusions of the study: 1. In this paper, high, middle and low permeability coefficients are set up to simulate the relationship between rainfall intensity and permeability, and their effects on slope stability under different rainfall intensities are discussed respectively. The results show that rainfall intensity will affect the stability of slope, but there is a limit value which is determined by saturated permeability coefficient. Therefore, we can estimate the critical rainfall intensity which leads to slope instability by the permeability of soil. 2. On the basis of previous studies, it is proposed that the total rainfall is constant, and the peak rainfall intensity in the rainfall process is classified according to the order of occurrence time, and the influence of each rain type on slope stability is investigated by numerical simulation, and the influence of each rainfall type on the slope stability is studied by numerical simulation. The results show that the stability of slope is influenced by the time sequence of peak value of rainfall intensity when the total amount of rainfall is certain. The earlier the peak value of rain intensity appears in the rainfall process, the earlier the safety factor decreases, while the peak value of rainfall intensity appears later. Although the safety factor decreases later, the decreasing range is larger, that is, the rain pattern with a peak rain intensity is more unfavorable to the slope. 3. Under the condition of k=0.001cm/s and k=0.1cm/s, the influence of rainfall intensity on slope stability is analyzed, and the rainfall of 233mm and 120 mm is obtained to make the slope unstable. The results show that only when the initial rainfall reaches a certain value, the safety factor of the slope will be reduced, and the early rainfall will lead to the slope reaching the state of imminent destruction in advance. It is very likely that slope instability will occur. 4. According to the uniform rain pattern and changing one or several influencing factors, three cases are used to simulate the influence of slope properties on slope stability under different rainfall intensity, such as slope type, slope angle, slope height, groundwater level, and so on, and three cases are used to simulate the influence of slope properties on slope stability under different rainfall intensity. The results show that the slope is more unstable when the slope angle and height are larger, and the value of safety factor before rainfall is determined by the rock and soil material parameters of the slope, and after the rainfall, the safety factor value is determined by the rock and soil material parameters of the slope, and the result shows that the slope angle and the slope height are more unstable. The saturated permeability coefficient and rainfall intensity are the important factors to determine the slope stability. The greater the rainfall intensity is, the faster the value of safety factor decreases, and the material permeability coefficient determines the influence degree of Rain Water on slope stability and groundwater level. It is concluded that when the rainfall intensity is high, the groundwater level surface changes greatly due to the influence of heavy rainfall infiltration, so the influence of groundwater level depth is not obvious in the case of heavy rainfall.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU43
本文编号：2448017
[Abstract]:The study of rainfall infiltration is of great significance to the stability of slope. The discussion on the mechanism of rainfall-induced landslides is gradually increasing in the rock-soil boundary, but the rainfall intensity, rainfall delay and geological conditions are considered in many aspects, such as rainfall intensity, rainfall delay and geological conditions, etc. The influence of rainfall pattern is often ignored. In this paper, Seep/w and Slope/w modules in Geo-studio are used to simulate rainfall infiltration and slope stability respectively, and the relationship between slope safety factor and time under different rainfall conditions is analyzed. The following are the main contents and conclusions of the study: 1. In this paper, high, middle and low permeability coefficients are set up to simulate the relationship between rainfall intensity and permeability, and their effects on slope stability under different rainfall intensities are discussed respectively. The results show that rainfall intensity will affect the stability of slope, but there is a limit value which is determined by saturated permeability coefficient. Therefore, we can estimate the critical rainfall intensity which leads to slope instability by the permeability of soil. 2. On the basis of previous studies, it is proposed that the total rainfall is constant, and the peak rainfall intensity in the rainfall process is classified according to the order of occurrence time, and the influence of each rain type on slope stability is investigated by numerical simulation, and the influence of each rainfall type on the slope stability is studied by numerical simulation. The results show that the stability of slope is influenced by the time sequence of peak value of rainfall intensity when the total amount of rainfall is certain. The earlier the peak value of rain intensity appears in the rainfall process, the earlier the safety factor decreases, while the peak value of rainfall intensity appears later. Although the safety factor decreases later, the decreasing range is larger, that is, the rain pattern with a peak rain intensity is more unfavorable to the slope. 3. Under the condition of k=0.001cm/s and k=0.1cm/s, the influence of rainfall intensity on slope stability is analyzed, and the rainfall of 233mm and 120 mm is obtained to make the slope unstable. The results show that only when the initial rainfall reaches a certain value, the safety factor of the slope will be reduced, and the early rainfall will lead to the slope reaching the state of imminent destruction in advance. It is very likely that slope instability will occur. 4. According to the uniform rain pattern and changing one or several influencing factors, three cases are used to simulate the influence of slope properties on slope stability under different rainfall intensity, such as slope type, slope angle, slope height, groundwater level, and so on, and three cases are used to simulate the influence of slope properties on slope stability under different rainfall intensity. The results show that the slope is more unstable when the slope angle and height are larger, and the value of safety factor before rainfall is determined by the rock and soil material parameters of the slope, and after the rainfall, the safety factor value is determined by the rock and soil material parameters of the slope, and the result shows that the slope angle and the slope height are more unstable. The saturated permeability coefficient and rainfall intensity are the important factors to determine the slope stability. The greater the rainfall intensity is, the faster the value of safety factor decreases, and the material permeability coefficient determines the influence degree of Rain Water on slope stability and groundwater level. It is concluded that when the rainfall intensity is high, the groundwater level surface changes greatly due to the influence of heavy rainfall infiltration, so the influence of groundwater level depth is not obvious in the case of heavy rainfall.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU43
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