泾阳南塬河滩村黄土滑坡的特征及致灾机理研究

发布时间：2018-06-10 19:21

本文选题：灌溉型黄土滑坡 + 形成机理　；参考：《长安大学》2015年硕士论文

【摘要】：黄土滑坡是黄土地区一种比较特殊的地质灾害,因其频发性、广布性、复杂性、灾难性等特点,严重威胁着人民生命财产和水电交通等工农业设施的安全。泾阳南塬自1976年引水灌溉以来,由于长期的漫灌导致塬区地下水位不断抬升,改变了塬区水文地质条件,致使黄土滑坡频繁发生,给人民的生命和财产带来了巨大的损失,同时严重影响地区社会经济的发展。本文以泾阳南塬河滩村典型黄土滑坡为例,通过野外实际调查、测量、勘探和室内实验等,分析研究了灌溉型黄土滑坡的发育特征、形成机理及致灾机理。主要研究内容如下:(1)通过现场实际调查,获得了研究区孕灾条件,主要包括:地形地貌、地质构造、水文气象条件及水文地质条件。通过室内试验,对黄土的颗粒组成、物理力学性质和结构特性进行了研究,就高陡后壁、后缘裂缝和落水洞等的形成进行了详细分析。(2)对河滩村黄土滑坡的发育特征进行了详细的调查,河滩村黄土滑坡较发育,主要具有如下特征:滑动突然、启程高速,滑动距离远,灾害严重,滑体多以块体方式运动、表面呈波浪状等特征。(3)河滩村黄土滑坡均为高速远程黄土滑坡,主要是由灌溉诱发。认为研究区灌溉型黄土滑坡主要经历3个阶段:蠕动—拉裂阶段→轻微液化—滑动阶段→严重液化—剧滑阶段。分析了蒋刘滑坡群演化机制,由于前次滑动改变了后缘地质条件,加之后缘拉张裂缝为灌溉水提供了良好的入渗通道,塬区滑坡频发,且具有演化的特点。(4)采用FLAC3D有限差分软件对西河滩黄土滑坡进行了数值模拟,研究了由于灌溉引起地下水位上升对坡体的影响。发现最大剪应力出现在饱和黄土层内,剪切破坏发生时土体在竖向有相对位移,塬面产生了拉裂缝,坡脚附近有隆起现象,坡体发生剪切破坏的塑性区呈圆弧形条带状区域,当整个塑性区在黄土层中贯通,坡体就从饱和黄土层剪出,最终导致斜坡失稳破坏。滑面形状和剪出口位置与实际相符,采用数值模拟较直观地分析了地下水位抬升对坡体的影响。
[Abstract]:Loess landslide is a special geological hazard in loess area. Because of its frequent, widespread, complex and disastrous characteristics, it seriously threatens the safety of industrial and agricultural facilities such as people's life, property and hydropower transportation. Since the diversion irrigation in 1976, the groundwater level has been rising continuously because of the long-term flood irrigation, which has changed the hydrogeological conditions, caused the loess landslide to occur frequently, and brought huge losses to the lives and property of the people. At the same time seriously affect the socio-economic development of the region. Taking typical loess landslide in Hetan village as an example, through field investigation, survey, exploration and laboratory experiments, this paper analyzes and studies the developmental characteristics, formation mechanism and disaster-causing mechanism of irrigated loess landslide. The main research contents are as follows: (1) based on the field investigation, the disaster preparedness conditions in the study area are obtained, including topography, geological structure, hydro-meteorological conditions and hydrogeological conditions. Through laboratory tests, the particle composition, physical and mechanical properties and structural characteristics of loess were studied. The development characteristics of loess landslide in Hetan Village are investigated in detail. The loess landslide in Hetan Village is relatively developed and has the following characteristics: sliding suddenly, setting off at high speed. The sliding distance is long, the disaster is serious, the sliding body moves in block way, the surface is wavy and so on.) Loess landslide in Hetan Village is high speed and long distance loess landslide, which is mainly induced by irrigation. It is considered that the irrigated loess landslide in the study area mainly goes through three stages: creeping-pulling crack stage and slight liquefaction-sliding stage and severe liquefaction-hyper-slip stage. The evolution mechanism of Jiangliu landslide group is analyzed. Because the previous slide changed the geological condition of the rear edge and the extension crack of the rear edge provided a good infiltration channel for irrigation water, the landslide occurred frequently in the tableland. The characteristics of evolution. (4) numerical simulation of loess landslide in Xihetan is carried out by using FLAC3D finite difference software, and the influence of the rise of groundwater level caused by irrigation on slope body is studied. It is found that the maximum shear stress occurs in the saturated loess layer, the soil has relative displacement in the vertical direction when the shear failure occurs, the tensile cracks occur on the plateau surface, the uplift phenomenon occurs near the slope foot, and the plastic zone of the shear failure of the slope body takes on a circular arc strip zone. When the whole plastic zone is connected in the loess layer, the slope body is cut out from the saturated loess layer, which leads to the failure of slope stability. The shape of the sliding surface and the location of the shear outlet are consistent with the actual situation. The influence of the uplift of the groundwater level on the slope body is analyzed intuitively by numerical simulation.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU444;P642.22

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