【作者】 王正芳；

【导师】 李锦辉；

【作者基本信息】 哈尔滨工业大学 ， 土木工程， 2011， 硕士

【摘要】 滑坡是最具有破坏性的自然灾害之一,它给人类带来巨大的生命和财产损失。降雨是诱发滑坡的主要因素之一。对于粘性土,其渗透系数较低,降雨不容易渗流到土体中。但由于干湿循环作用或者土体的变形等作用,在土体中会产生裂隙,这些裂隙的存在使得雨水更容易的入渗到土体中,最终导致边坡的稳定性降低。尽管研究者已经认识到评价裂隙边坡的稳定必须考虑裂隙的影响,但是目前还缺乏系统的理论去描述裂隙的作用,现有的评价裂隙对边坡渗流及稳定性影响的方法过于简化,例如,赋予裂隙或者裂隙土较大的渗透系数;认为裂隙充满水,裂隙作为水头边界条件,等等。其实裂隙的渗透系数并不是常量,裂隙的初始状态也是非饱和的,在降雨过程中,裂隙存在着饱和-非饱和的过程。这一部分在岩土力学方面有较多的研究,但是基本没有应用到土体边坡的渗流分析及评价土体边坡的稳定性方面。裂隙的上述水力特性和裂隙的形态有直接的关系。裂隙的开度及分布决定着裂隙的饱和渗透系数,裂隙的渗透系数函数和土水特征曲线也与裂隙的开度及其分布有关。综上,本研究的目的是在研究裂隙的空间分布的基础上,研究裂隙的水力特性,进而研究裂隙对土体边坡的稳定性影响。本研究的主要内容包括三方面:其一,裂隙开度的随机场参数。本课题采用随机场理论得到裂隙的随机场特征参数。其二,建立裂隙的土水特征曲线和渗透系数函数的数值模型。其三,采用本研究得到的稀疏分布大裂隙的土水特征曲线和渗透系数函数,利用数值模拟方法,分析降雨条件下裂隙土边坡的稳定性。并研究裂隙的深度、位置、降雨强度等对边坡稳定性的影响。本文主要研究成果为:其一,应用live-wire算法提取了裂隙的图像,并建立了裂隙开度的随机场模型,然后验证了裂隙开度的概率分布,发现裂隙开度符合对数正态分布和正态分布。接着求取了裂隙开度的随机场参数:应用指数型函数拟合裂隙开度的自相关函数,应用相关函数法求取裂隙开度的相关距离,研究发现当取样间距小于相关距离的1/10时,相关距离的结果可靠。其二,基于随机场理论采用数学推导法得到裂隙的土水特征曲线,并应用数值方法,考虑圈闭效应,得到裂隙的土水特征曲线,结果表明考虑圈闭效应能较好的模拟裂隙的土水特征曲线有较大的残余含水量。其三,考虑裂隙的饱和-非饱和水力特性研究了裂隙对边坡渗流及稳定性的影响,结果表明,裂隙的深度越深,降雨时长越长,初始孔隙水压力越高,雨水更容易从裂隙处入渗到土体中,同时降低边坡的稳定性。更多还原

【Abstract】 Landslide is one of the most devastating natural disasters; it gives one of mankind tremendous loss of life and property. Rainfall is one of the main factors induced landslides. For cohesive soil, rainfall is not easy to seepage to, because of the low permeability coefficient. But because of dry wet circulation effect or deformation of soil, the cracks will be produced; these cracks make rain easy to infilt into soils, which eventually led to the stability of the slope reduced. The researchers, though, have come to realize that when evaluate the stable of slope, the crack must be considered, but it is still lack of systematic theory to describe the role of crack, the methods on the stability with crack were too simplified, for example, gives crack or crack soil larger permeability coefficient; Think crack filled with water, crack is treated as head boundary conditions, etc.Actually fracture permeability coefficient is not constant, the initial condition of crack is not saturated, in the rainfall process, the crack exist saturated-unsaturated process. This part has some research, but basically no application to soil seepage analysis and evaluation of the slope stability of soil slope. The hydraulic characteristics of crack are directly related to the form of the crack. the aperture of crack and distribution of the crack determine the permeability of crack.. the soil water characteristic curve also have relationship with the aperture and its distributionIn conclusion, the purpose of this study is to study the spatial distribution of the crack, then study the hydraulic characteristics of crack, and then we study the stability of soil slopes with crack.The main focus of this study includes three aspects: firstly, the crack aperture with random field parameters. Secondly, establish the soil water characteristic curve of crack and permeability function in the numerical model. Thirdly, based on the soil water characteristic curve and permeability function of the crack, using numerical simulation method, analysis stability of crack soil slope under rainfall condition. And study the depth and crack position, rainfall intensity on the influence of slope stability.The main result of this study also includes three aspects: firstly, extract the edge of crack from the image applying the live-wire method, and set up the random field theory model of crack, and verify the probability distribution of crack aperture, found that the probability distribution of the crack follew the log-normal distribution and normal distribution. Then calculate the parameters of random field theory : the application of exponential function fitting the autocorrelation function of the crack and application correlation function method calculating the scale of fluctuation, the study found that when sampling space less than 1/10 of The scale of fluctuation, the results of the scale of fluctuation are reliable. Secondly, based on the theory with the random field method the soil water characteristic curves can be obtained, and application of numerical method, consider trap effect, get the soil water characteristic curve, the results show that the results is better considering traps effect. This can reflect soil water characteristics curve have larger residual water content. Third, consider the hydraulic characteristics of crack, the influence of seepage and stability, the results show that the crack of the deep, longer rain time, higher initial pore water pressure, the more likely the rain infiltration in soils from crack , at the same time, reduce the stability of the slope.更多还原