不同降雨条件下吾隘滑坡稳定性分析

发布时间：2018-01-05 19:38

本文关键词：不同降雨条件下吾隘滑坡稳定性分析　出处：《成都理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：吾隘滑坡位于广西南丹县吾隘镇,其所在地区位于云贵高原向桂西北丘陵过渡的斜坡地带,山地丘陵地貌分布广泛,斜坡表面广泛覆盖着残坡积土。桂西北是广西滑坡频发的地区,其主要发生在连续阴雨、暴雨的时段。而针对南丹县地区降雨型滑坡的相关研究较少,因此,通过对吾隘滑坡的研究,既可以排除其对周边群众的安全威胁,还可以为其所在区类似滑坡稳定性分析提供参考。本文以吾隘滑坡为研究对象,进行了野外踏勘以及钻探;查明了滑坡的边界、形态及规模特征、滑坡体结构特征及其变形特征;进行了现场试验研究以及室内试验分析;对滑坡的变形演化机制及变形破坏模式进行了分析;运用极限平衡法及有限差分法,对在降雨条件下的吾隘滑坡进行稳定性分析以及应力应变分析。主要结论和认识如下:(1)现场勘查表明:吾隘滑坡地处低山沟谷地貌,坡度较陡,存在两处较明显的滑塌,且在滑坡中后缘有明显的拉张裂缝。(2)通过钻探,查明了滑坡的地层以及物质组成。进行了原位双环试验,测得了滑体土的渗透性,属于中等透水。而下伏基岩为弱透水的砂质泥岩,其起到相对隔水的作用,这有利于地下水在滑体内富集,这对滑坡稳定性不利。(3)针对当地气候条件,考虑了不同降雨条件,对吾隘滑坡地下水与负孔隙水压力进行了分析,得出:(1)降雨强度越大,相同时间内滑坡体地下水位上升越快,负孔隙水压力减小的越快,负孔隙水压力等值线弯曲程度越大;(2)同一降雨强度下,随着降雨历时增大,滑坡体的负孔隙水压力逐渐小,地下水位逐渐抬升;(3)在相同总降雨量下,雨强小、历时长的降雨,更加充分地渗透到滑坡体内;而雨强大、历时短的降雨,在靠近坡体表面形成暂态饱和区,降雨不能充分入渗坡体;(4)降雨停止后,渗入滑坡体的雨水以及地表积水还在向坡体内运移,在一定时间内,地下水位还会缓慢抬升,坡体内的负孔隙水压力也会逐渐减小,之后,随着地下水的排泄,坡体内的地下水会缓慢恢复到初始状态。(4)基于非饱和土力学理论,对不同降雨条件下滑坡稳定性进行了分析,得出:(1)48小时内,雨强越大,滑坡体稳定性系数降幅越大,下降速率也越快;(2)随着降雨历时的延长,滑坡体的稳定性系数逐渐减小,达到一定时间后,滑坡体处于欠稳定的状态;(3)相同总降雨量下,雨强小、历时长的降雨对滑坡体稳定性更加不利;(4)在降雨期间和降雨停止后一天内,吾隘滑坡的稳定性系数呈递减的趋势。降雨停止后一天时,滑坡处于欠稳定状态。降雨停止3天后,吾隘滑坡的稳定性系数缓慢回升。(5)考虑了天然状态及降雨条件,对吾隘滑坡的变形与稳定性进行了数值模拟研究,得出:在天然状态下,吾隘滑坡处于基本稳定的状态,降雨条件下发生缓慢滑动,拉动后缘变形,并挤压前缘,这与现场调查情况有较好的一致性。
[Abstract]:Wu AI landslide is located in Guangxi County of Nandan Wu AI Town, the area is located in the Yunnan Guizhou Plateau to the northwest of Guangxi hilly slope transition zone, hilly landforms are widely distributed, the slope surface widely covered with residual soil. In the northwest of Guangxi Guangxi landslide prone areas, which mainly occurred in the continuous rain, rain and for hours. Less relevant research, rainfall area of Nandan County landslide therefore, through the study of landslide of Wu AI, which can eliminate the surrounding masses of security threats, can also provide reference for similar area analysis of landslide stability in this paper. The Wu AI landslide as the research object, the field exploration and drilling; landslide the boundary to identify the morphology and size characteristics, structure characteristics and deformation characteristics of the landslide are analyzed; field tests and laboratory tests; the failure modes of deformation and deformation mechanism of Landslide Evolution Are analyzed; by using limit equilibrium method and finite difference method, the under rainfall Wu AI landslide stability analysis and stress strain analysis. The main conclusions are as follows: (1) the scene showed that Wu AI landslide is located in low mountain valley landform, a steep slope, there are two obvious the collapse and landslide in the trailing edge has obvious tensile cracks. (2) identified by drilling, landslide formation and material composition. The in situ loop test, permeability test with landslide soil, which is of medium grade. The bedrock is a low permeability of sandy mudstone, the play the relative water resisting effect, which is conducive to the enrichment of groundwater in the slide body, which is detrimental to the landslide stability. (3) according to the local climate conditions, taking into account the different rainfall conditions of Wu AI landslide groundwater and negative pore water pressure were analyzed, concluded: (1) the greater intensity of rainfall at the same In the landslide groundwater level rise faster, the faster the negative pore water pressure decreases, the bending degree of negative pore water pressure contour more; (2) the same rainfall intensity, with rainfall increasing, the negative pore water pressure of the landslide gradually small, underground water level rising; (3) in the same the total rainfall, rainfall intensity, rainfall duration, more fully penetrate into the landslide body; and the rain strong, short duration of rainfall, the formation of transient saturated zone near the slope surface, rainfall is not fully infiltration slope; (4) after the stop of rainfall infiltration sliding slope rainfall and surface water also to the slope movement, in a certain period of time, the groundwater level will slowly rise, after the negative pore water pressure in the slope will gradually decrease, and with the groundwater discharge, slope groundwater will slowly return to the initial state. (4) based on the theory of unsaturated soil mechanics, the different Under the condition of rainfall on landslide stability is analyzed, concluded that: (1) within 48 hours, the greater the rainfall intensity, slope stability coefficient the greater the decline, decline rate is faster; (2) with the rainfall duration, the stability coefficient of landslide decreases gradually, reached after a certain time, the landslide is unstable the state; (3) the same total rainfall, rainfall intensity, rainfall duration on landslide stability is more unfavorable; (4) in the rain and after one day, the stability coefficient of landslide presenting Wu AI decreased. One day after the rain stopped, the landslide is in an unstable state. The rain stopped after 3 days, the stability coefficient of landslide Wu AI slowly recovered. (5) considering the natural state and rainfall conditions, the deformation and stability of Wu AI landslide were studied by numerical simulation, obtained under natural state, Wu AI landslide is in stable state, the condition of rainfall There is a slow sliding, pulling the back edge deformation and pressing the front edge, which is in good agreement with the field investigation.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P642.22

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