降雨与滴灌条件下裂隙黄土滑坡试验及数值分析

发布时间：2018-10-09 07:51

【摘要】：水是黄土滑坡的诱发因素之一,本文通过室内试验研究了雨水的入渗过程、边坡的变形破坏特征以及降雨入渗中的裂隙演变特征。监测并分析降雨过程中土体含水率、孔隙水压力以及基质吸力的变化过程,分析裂隙黄土边坡变形破坏演变规律。开展了黄土边坡的滴灌试验,分为60°和45°边坡进行试验,研究了滴灌对边坡稳定性的影响。进行压力板仪试验,获取了黄土的土-水特征曲线,结合渗流理论、弹性力学,获取二维非饱和土的水-力耦合控制方程。用COMSOL Multiphysics有限元软件对非饱和土渗流耦合控制方程进行计算,探索黄土边坡降雨入渗问题,对模型试验与数值结果进行比较分析。主要得出以下几点结论:(1)在降雨过程中,边坡变形比较明显,受裂隙影响,在裂隙周围不断的产生拉裂缝,且呈现多级演化特征。裂隙为坡体的水分运移提供优先通道。孔隙水压力突变往往伴随滑坡或局部大变形的产生,坡体内孔隙水压力随着降雨时间的增加而增大,坡脚、裂隙和坡肩孔隙水压力变化最为显著。(2)在室内滴灌试验下,边坡的破坏类型可归纳为坡脚局部滑塌-坡肩局部滑动-整体滑坡,坡脚和坡肩出现多次局部滑塌,孔隙水压力的突变是滑坡的主要征兆。坡表变形较明显,边坡由外向内位移逐渐减小。60°边坡滑动启动时间要比45°边坡滑动启动时间要早,更易发生整体滑动,滑动距离远。(3)数值计算表明随着降雨时间增大,水平位移也逐渐变大,但变化速率逐渐变缓,坡面处水平位移较大,其中坡脚水平位移最为集中。近坡表部位总位移较大,坡肩、坡脚部位最为突出,由坡表向坡体内部总位移逐渐变小。裂隙为水的运移提供了优先路径,裂隙处的孔隙水压力变化明显。
[Abstract]:Water is one of the inductive factors of loess landslide. The infiltration process of Rain Water, the deformation and failure characteristics of slope and the evolution characteristics of cracks in rainfall infiltration are studied in this paper. The changes of soil moisture content pore water pressure and matrix suction during rainfall are monitored and analyzed. The deformation and failure evolution of fractured loess slope is analyzed. The experiment of drip irrigation on loess slope was carried out, which was divided into 60 掳and 45 掳slope, and the influence of drip irrigation on slope stability was studied. The soil-water characteristic curve of loess was obtained by means of pressure plate test. Combined with seepage theory and elastic mechanics, the water-force coupling governing equation of two-dimensional unsaturated soil was obtained. The coupling governing equation of unsaturated soil seepage was calculated by COMSOL Multiphysics finite element software, and the rainfall infiltration problem of loess slope was explored. The model test and numerical results were compared and analyzed. The main conclusions are as follows: (1) in the process of rainfall, the slope deformation is obvious, affected by cracks, the tension cracks are constantly produced around the cracks, and the characteristics of multi-level evolution are presented. The fissure provides the preferential passage for the water movement of the slope body. The sudden change of pore water pressure is often accompanied by landslide or local large deformation. The pore water pressure in slope increases with the increase of rainfall time. The pore water pressure of slope foot, fissure and shoulder is the most significant. (2) under the indoor drip irrigation test, the pore water pressure in slope is the most significant. The failure types of slope can be summed up as local sloughing at the foot of the slope, local sliding at the shoulder of the slope and a whole landslide, and several local landslides at the foot of the slope and the shoulder of the slope. The abrupt change of pore water pressure is the main sign of the landslide. The slope surface deformation is obvious, and the slope sliding start time is earlier than that of 45 掳slope sliding starting time. (3) numerical calculation shows that with the increase of rainfall time, the sliding start time of slope is shorter than that of 45 掳slope. (3) numerical calculation shows that the sliding start time increases with rainfall time. The horizontal displacement also became larger, but the change rate gradually slowed down, and the horizontal displacement at the slope was larger, among which the horizontal displacement at the foot of the slope was the most concentrated. The total displacement of the near slope surface is larger, the slope shoulder and the slope foot are the most prominent, and the total displacement from the slope surface to the slope body becomes smaller gradually. The fissure provides a preferential path for water migration, and the pore water pressure changes obviously.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.22

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