【摘要】：研究降雨入滲對(duì)邊坡的穩(wěn)定具有重要的意義，巖土界對(duì)降雨誘發(fā)滑坡機(jī)制的探討逐漸增多，但多考慮的是降雨強(qiáng)度、降雨延時(shí)以及地質(zhì)條件等方面，常常忽視了降雨雨型的影響，本文通過(guò)Geo-studio中的Seep/w和Slope/w模塊分別模擬降雨入滲和邊坡穩(wěn)定，分析不同降雨條件下，邊坡安全系數(shù)隨時(shí)間變化的關(guān)系。以下為主要研究?jī)?nèi)容和結(jié)論： 1.本文首先設(shè)置了高、中、低不同的滲透系數(shù)，針對(duì)降雨強(qiáng)度與滲透性的關(guān)系做一系列的模擬，分別探討它們?cè)诓煌涤陱?qiáng)度下對(duì)邊坡穩(wěn)定的影響。分析得到了：降雨強(qiáng)度會(huì)影響邊坡的穩(wěn)定性，但它的影響存在一個(gè)極限值，而這個(gè)極限值由飽和滲透系數(shù)決定。所以我們?cè)谇笕?dǎo)致邊坡失穩(wěn)的臨界雨強(qiáng)時(shí)可通過(guò)土壤的滲透性作為推估條件。 2.在前人的研究的基礎(chǔ)上，提出了：總降雨量一定，降雨過(guò)程中雨強(qiáng)峰值按出現(xiàn)的時(shí)間先后順序分類的七種雨型，通過(guò)數(shù)值模擬分別探究各雨型對(duì)邊坡穩(wěn)定的影響，結(jié)果表明降雨總量一定時(shí)雨強(qiáng)峰值出現(xiàn)的時(shí)間先后順序影響著邊坡穩(wěn)定，降雨過(guò)程中越先出現(xiàn)雨強(qiáng)峰值的，安全系數(shù)越早降低，而雨強(qiáng)峰值較后出現(xiàn)的，，盡管安全系數(shù)較晚降低，但下降幅度較大，即較晚出現(xiàn)雨強(qiáng)峰值的雨型對(duì)邊坡更為不利。 3.對(duì)均勻雨型在滲透系數(shù)k=0.001cm/s和k=0.1cm/s的情況下，分析前期降雨強(qiáng)度對(duì)邊坡穩(wěn)定的影響，得到該兩種滲透系數(shù)使邊坡達(dá)到不穩(wěn)定的前期降雨量分別為233mm和120mm。結(jié)果表明：僅僅在前期降雨量達(dá)到某一定值時(shí)，邊坡的安全系數(shù)才會(huì)降低，前期降雨會(huì)提前導(dǎo)致邊坡達(dá)到瀕臨破壞的狀態(tài)，若之后再遇到較大強(qiáng)度的降雨時(shí)，則極有可能發(fā)生邊坡失穩(wěn)。 4.針對(duì)均勻雨型，改變其中某一或幾個(gè)影響因素，通過(guò)三個(gè)案例分別模擬不同邊坡土體類型、坡角、坡高、地下水位等邊坡性質(zhì)在不同降雨強(qiáng)度下對(duì)邊坡穩(wěn)定的影響，從而確定不同性質(zhì)和類型的邊坡影響因素的影響水平，結(jié)果得到，坡角、坡高越大邊坡越不穩(wěn)定，降雨前的安全系數(shù)值由邊坡巖土材料參數(shù)決定，降雨發(fā)生后，材料飽和滲透系數(shù)、降雨強(qiáng)度為決定邊坡穩(wěn)定的重要因素，其中降雨強(qiáng)度越大，安全系數(shù)值下降越快，而材料滲透系數(shù)決定了雨水對(duì)邊坡穩(wěn)定的影響程度，地下水位方面，得出降雨強(qiáng)度較高時(shí)，由于受到強(qiáng)降雨入滲的影響地下水位面變化較大，因此地下水位深度在強(qiáng)降雨的情況下影響較不明顯。
[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.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU43

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