【作者】 陈伟；

【导师】 骆亚生；

【作者基本信息】 西北农林科技大学 ， 岩土工程， 2013， 硕士

【摘要】 黄土在我国广泛分布，黄土滑坡问题严重。近年来，对滑坡灾害的研究和治理日益引起人们的重视，但由于黄土特殊的结构性和力学特性，导致对滑坡内在机理的研究具有很大的难度。为了对黄土滑坡内在规律有进一步的了解，本文以杨凌黄土为研究对象，进行了黄土边坡室内模型试验，探索边坡在人工降雨作用下的渐进破坏规律。同时利用FLAC3D分析了边坡在不同含水率和雨水入渗不同深度下，边坡变形发展、剪切滑移和失稳渐进破坏过程，最后分析了边坡在坡顶加载条件下的渐进破坏过程，本文取得的主要结论如下：（1）在降雨初期，水分平均入渗率为86%，之后随着地表径流增加，入渗速率降低，最后维持在40%左右。在整个过程中，土体的渗透能力逐渐降低，边坡某些区域土体达到饱和状态。（2）在降雨作用下，边坡开始会产生坡面冲蚀和水土流失，并出现许多张拉裂缝和冲蚀沟，当这些裂缝在坡体内部相互贯通时，潜在滑动面形成，随后雨水进一步入渗就会产生较大规模崩滑，滑动区为坡面以下0~1.6m之间。（3）边坡内部只有含水率变化较大的区域，土体运动才最剧烈，这说明水分对边坡失稳有很大的影响。含水率增加致使土体有效应力降低以及导致水分向坡外的渗透力增加，从而使边坡不稳定。(4)在降雨入渗致使土体含水率变化条件下，随着边坡均布含水率的增加，坡脚的局部开始出现应变局部化现象；当边坡含水率达到一定值时，剪切带从坡脚开始出现，随着含水率继续增加，剪切带逐步发展，当边坡湿度上升到一定程度时后，剪切带贯通，边坡开始滑动。（5）在雨水不同入渗深度条件下，随着入渗深度的增加，边坡经历3个阶段。第一阶段，边坡表层土体迅速失稳，但边坡整体稳定；第二阶段，雨水进一步入渗，致使坡体内部开始出现塑性区和表面裂缝，坡体稳定性开始大幅下降；第三阶段，雨水入渗到坡体内部，致使裂缝和塑性区贯通，剪切带从坡脚到坡顶贯通，边坡失稳破坏。（6）边坡破坏时坡体明显的分为滑动体和稳定体两部分，它们之间具有明显的位移梯度差值。同时，滑动体上各点的运动既有土体本身的变形运动也有滑动体的滑动，并且土体本身的变形运动远大于滑动体整体的滑动。更多还原

【Abstract】 Loess is widely distributed in China and loess landslide is the serious problem. In recentyears with the implementation of the western development and the rapid rise of the westerneconomy, research and governance for the landslide has attracted much attention. Due to thespecial structural and mechanical properties of loess, it is great difficulty to study themanagement of the internal mechanism of the landslide. In order to have a betterunderstanding of the inherent law of loess landslide, in this paper firstly, it work up slopeindoor model based on loess in Yangling to explore the mechanical response andmorphological features of slope in the role of artificial rainfall by methods of digitaldeformation measurement techniques and measurement device. The FLAC3D was also usedto analyze the progress of slope’s changing deformation, shear slipping and damage due to theinstability under different water content and infiltration depth. The gradual damage progressof slope under the load at the top of slope was analyzed in the end. It could be concluded thatin this paper:(1) Before rainfall, average infiltration rate of water was86%. And then with thegrowth of Surface runoff, infiltration rate was reduced till it maintained at about40%.Through the process, the permeability of the soil was gradually reduced and certain areas ofsoil in slope became saturation.(2) In affect of rainfall, slop began to produce hill slope erosion and soil erosion withmany tension cracks and erosion ditch. When these cracks inside the slope wereinterconnected, it formed potential sliding surface. Then the further infiltration of rain wouldproduce the massive landslides, and the sliding zones were from0to1.6m below the slope.(3) The larger slope internal moisture content changes in the larger area of soilmovement is most intense. This showed that the water had a great influence on the slopefailure. The increase in moisture content caused the soil effective stress reduction andincreased the penetration of moisture to the outer slope, so that the slope was instable.(4) Under the condition of rainfalls, the soil’s water content changed by the infiltration,and the stress occurred in the part toe of slope due to the increasing water content of slope. When the water content increased to a standard value, the shear band happened from the toeof slope, and expanded gradually with the increasing water content. When the humidity inslope arrived to a certain extent, the perforative shear band formed, then the slope glided.(5) Under the condition of different infiltration rate of rainfall, the slope experienced3stages with the increasing infiltration depth. The first stage: the slope soil mass in the surfacebecome unstability rapidly, but the slope body was still stability. The second stage: with theincreasing infiltration depth, the plastic zone and surface cracks occurred at the slope interior,and the slope stability decreased substantially. The third stage: because of the waterinfiltrating into the interior, the cracks and plastic zone become an entirety, and the shear bandlinked up from toe to top, which caused the unstability damage.(6) The slope body could be obviously divided into two parts: slide mass and stablemass. When the slope failure happened, there was a apparent gradient difference indisplacement between two of them. Meanwhile, the movement of pots on the slide massincluded not only the amoeboid locomotion, but also the slipping of the slide mass itself, andthe value of former was much larger than the value of latter.更多还原