基于饱和与非饱和渗流崩塌体滑坡稳定性研究

发布时间：2018-01-26 08:37

本文关键词： 饱和-非饱和降雨入渗水位骤降基质吸力边坡稳定性条分法　出处：《长沙理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：株洲枫溪港滑坡是枫溪河岸边坡受到雨水侵蚀、河流冲刷以及洪水位下降等因素的影响而形成的崩塌体滑坡。该崩塌体滑坡属于次生堆积体,物质成分以土质和破碎岩体为主,结构松软破碎,粒间结合力差,透水性强,力学性质易受水文因素的影响。长时间的降雨入渗和洪水位的周期性波动,对坡体内渗流场的影响很大,威胁着滑坡的整体稳定性。研究降雨入渗和水位骤降条件下崩塌体滑坡的稳定性具有重要的意义。本文以枫溪港滑坡为例,基于饱和-非饱和渗流理论研究了降雨入渗和水位骤降对崩塌体滑坡渗流场的影响,得到了坡体内孔隙水压力的变化规律,在此基础上结合非饱和土抗剪强度理论和极限平衡条分法研究了滑坡的稳定性。本文主要取得了以下研究成果：(1)降雨强度越大,单位时间内滑坡体的雨水入渗量越多,滑坡体内的孔隙水压力变化越大,基质吸力降低幅度越大,对滑坡稳定性越不利。降雨第3天,降雨强度分别为0.0003m/h、0.0015m/h、0.006m/h时,滑坡安全系数分别降低了5%、17.4%、20%。当降雨强度大于滑坡体的渗透系数时,枫溪港滑坡在降雨历时3天内会发生失稳破坏。(2)降雨历时越长,滑坡体内孔隙水压力的变化越大,水位线上升越高,对滑坡稳定性越不利。降雨强度为0.0015m/h时,降雨历时分别为2天、3天、4天时,滑坡的安全系数由1.16分别降低至1.022、0.958、0.917,降低幅度分别为11.9%、17.4%、21%。降雨强度为0.0015m/h和0.006m/h时,分别在降雨第54小时和第42小时发生滑坡灾害。(3)水位骤降能引起滑坡体内形成滞后的孔压差,水位下降速度越快,坡体内孔隙水压力消散越慢,坡体内指向坡外的渗透力越大,对滑坡的稳定性越不利。同一高度水位分别以速度0.1m/d、0.4m/d和2m/d下降到同一稳定水位高度(7m)时,滑坡安全系数降低幅度分别为24%、31%和35%。当水位下降速度达到0.4m/d,枫溪港滑坡就有发生失稳破坏的隐患。(4)初始水位高度越高,水位下降至同一稳定水位所需时间越长,坡体内积累的孔压差越大,形成的渗透力也越大,对滑坡的稳定性也越不利。当坡外初始水位高度分别为20m、15m、lOm的河水位以相同速度下降到同一稳定水位(5m)后,坡体内的浸润线高度分别降至16m、14m、11m,滑坡安全系数的降低幅度分别为49%、35%、12%,并且分别在第8天、4天、3天出现滑坡灾害。
[Abstract]:Fengxigang landslide in Zhuzhou is a landslide formed by the influence of Rain Water erosion, river scour and water level decline. The landslide belongs to the secondary accumulation body. The main material composition is soil and rock mass, the structure is soft and broken, the intergranular binding force is poor, the permeability is strong, the mechanical property is easily affected by hydrological factors, the long-term rainfall infiltration and the periodic fluctuation of flood water level. It is of great significance to study the stability of landslide under the condition of rainfall infiltration and sudden drop of water level. This paper takes Fengxigang landslide as an example. Based on saturated-unsaturated seepage theory, the influence of rainfall infiltration and water level drop on seepage field of landslide is studied, and the variation law of pore water pressure in slope is obtained. On this basis, the stability of the landslide is studied by combining the shear strength theory of unsaturated soil and the ultimate equilibrium strip method. The following research results are obtained in this paper: 1) the rainfall intensity is greater. The more Rain Water infiltration amount of landslide body per unit time, the greater the pore water pressure in landslide, the larger the decrease of matrix suction, the more unfavorable to landslide stability. The third day of rainfall. When the rainfall intensity was 0.0003 m / h, 0.0015 m / h and 0.006 m / h, the safety factor of the landslide was reduced by 5% or 17.4% respectively. 20. When the rainfall intensity is greater than the permeability coefficient of the landslide, the longer the rainfall duration is, the more the pore water pressure in the landslide will change. When the rainfall intensity is 0.0015 m / h, the rainfall duration is 2 days, 3 days and 4 days, respectively. The safety factor of the landslide was reduced from 1.16 to 1.022 ~ 0.958 ~ 0.917, respectively, and the decrease range was 11.9% or 17.4% respectively. 21. when the rainfall intensity is 0.0015mrh and 0.006mrh. Landslide disaster occurred in the 54th hour and the 42nd hour of rainfall respectively) the sudden drop of water level can cause the formation of lag pore pressure difference in the landslide. The faster the water level drops, the slower the pore water pressure dissipates. The greater the permeability of the slope towards the outside of the slope, the more unfavorable to the stability of the landslide. The water level at the same height is at a velocity of 0.1 m / d respectively. When 0.4m / d and 2m/ d fall to the same stable water level (7m), the landslide safety factor decreases by 24.1% and 35m / d, respectively, when the water level drops at a rate of 0.4m / d. The higher the initial water level height is, the longer it takes for the water level to fall to the same stable water level, the larger the pore pressure difference accumulated in the slope, the greater the permeability. The more unfavorable to the stability of the landslide, when the initial water level outside the slope is 20m ~ 15mO _ m, respectively, the level of the river drops to the same stable water level (5m) at the same speed. The depth of the infiltration line in the slope was reduced to 16 m ~ 14 m ~ (-1) and the safety factor of the landslide was decreased by 49 ~ 35 ~ (12) and 4 days respectively on the 8th day. Landslide disaster occurred in 3 days.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P642.22;TU43

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