延安地区典型滑坡的形成机理研究

发布时间：2018-12-17 03:52

【摘要】：延安地区位于黄土高原的中部,黄土滑坡十分发育。根据延安地区地质灾害详细调查结果,延安地区现有滑坡1350处,几乎全部为黄土滑坡。这些滑坡诱发因素不尽相同,有的由降雨、河流侵蚀等自然因素引起,有的由人工开挖与堆载、水库蓄水等工程活动所引起。滑坡的诱发因素不同,其形成机理也不同,在防治上就要采取不同的防治措施。因此,研究延安地区不同诱发因素形成滑坡的机理,可以为滑坡灾害的防治提供理论依据和技术支撑,有利于制定切实可行的防灾减灾规划,避免或减少人员伤亡和财产损失。本文采用对已有调查资料的分析统计、野外滑坡要素测量、典型滑坡点取样测试、室内岩土测试、数值模拟等技术方法,开展主要诱发因素引起滑坡的机理分析,所做的工作及取得的主要成果如下:(1)对延安地区地质灾害详细调查的结果进行统计、分析,归纳总结了延安地区滑坡的发育类型;分析了延安地区形成滑坡的主要控制因素及触发因素;(2)依据老滑坡、新滑坡的形成条件,对延安地区的黄土分别做了重塑饱和黄土的反复直剪试验、原状黄土在三轴条件下的剪切试验,获得了重塑饱和黄土和原状黄土的强度特征。并对该地区的泥岩、砂岩做了单轴抗压试验和压缩试验;通过回弹试验,分析了砂岩的结构面强度。(3)在分析了降雨入渗方式、入渗规律的基础上,以富县吉子现乡滑坡、阎家沟滑坡、延炼滑坡为典型实例,通过数值模拟,再现了降雨通过黄土孔隙、节理入渗,降雨通过黄土中卸荷裂缝、落水洞等集中通道流入,以及降雨通过水分逐渐往下迁移分别形成滑坡的过程,分析了不同入渗方式形成滑坡的机理。(4)以庵里滑坡、印台山滑坡以及洛川加油站滑坡为例,通过数值模拟,分析了溯源侵蚀、河流侧蚀及河流或沟谷下蚀形成滑坡的过程,通过对比各个阶段滑动面上应力及抗剪强度的变化,解释了河流不同侵蚀方式形成滑坡的机理。并模拟了滑坡的运动过程,获得了滑坡的滑动范围及运动距离。(5)根据水库蓄水在迎水岸诱发滑坡的特征,概化典型模型,数值模拟了在迎水岸库水位上涨及骤降时不同时段孔隙水压力及剪应力的变化,分析了滑面不同位置剪应力及抗剪强度的关系,以及岸坡稳定性随时间的变化,揭示了迎水岸水库蓄水诱发滑坡的机理。以赵家岸滑坡作为背水岸滑坡的实例,模拟分析了库水位上涨和下降时孔隙水压力及应力的变化,揭示了水库蓄水在背水岸诱发滑坡的机理。(6)选取三亩台滑坡、南窑村高边坡、龙首村高边坡三个典型案例,对人工开挖引起的新滑坡进行数值分析,解释了人工开挖形成新滑坡的机理。以王窑村滑坡为例,解释了开挖导致老滑坡复活的机理。以袁和庄滑坡为例,分析了堆载后坡体应力及抗剪强度的变化,解释了堆载导致的滑坡形成机理。
[Abstract]:Yan'an area is located in the middle of the Loess Plateau, loess landslide is very developed. According to the detailed investigation results of geological hazards in Yanan area, there are 1350 landslides in Yanan area, almost all of which are loess landslides. The induced factors of these landslides are different, some are caused by natural factors such as rainfall and river erosion, and some are caused by engineering activities such as artificial excavation and heaps, reservoir water storage and so on. The induced factors of landslide are different, and the formation mechanism of landslide is different, so different measures should be taken to prevent and cure landslide. Therefore, studying the mechanism of landslide formation by different induced factors in Yan'an area can provide theoretical basis and technical support for the prevention and control of landslide disasters, which is helpful to formulate feasible plans for disaster prevention and mitigation and to avoid or reduce casualties and property losses. In this paper, the analysis and statistics of the existing investigation data, the measurement of landslide elements in the field, the sampling test of typical landslide points, the indoor geotechnical test and numerical simulation are used to analyze the mechanism of the landslide caused by the main induced factors. The work and main results obtained are as follows: (1) the results of detailed investigation of geological hazards in Yanan area are statistically analyzed, and the development types of landslide in Yanan area are summarized. The main controlling factors and triggering factors of landslide formation in Yan'an area are analyzed. (2) according to the forming conditions of the old landslide and the new landslide, the repeated direct shear tests of the remolded saturated loess and the shear test of the undisturbed loess under the triaxial condition have been made on the loess in Yan'an area. The strength characteristics of remolded saturated loess and undisturbed loess are obtained. The uniaxial compression test and compression test are also done for the mudstone and sandstone in this area. The structural surface strength of sandstone is analyzed by springback test. (3) based on the analysis of rainfall infiltration mode and infiltration law, taking Jizixian landslide, Yanlian landslide and Yanjiagou landslide in Fuxian County as typical examples, numerical simulation is carried out. It reappears the process of rainfall flowing through loess pore, joint infiltration, rainfall through loess unloading crack, falling water tunnel and other concentrated channels, and rainfall gradually moving down to form landslide. The mechanism of landslide formation in different infiltration modes is analyzed. (4) taking the Anli landslide, Yintai Mountain landslide and Luochuan Gas Station landslide as examples, the traceability erosion is analyzed by numerical simulation. The process of river side erosion and river or valley erosion to form landslide is discussed. By comparing the stress and shear strength on the sliding surface of each stage, the mechanism of river landslide formation with different erosion modes is explained. The movement process of landslide is simulated, and the sliding range and distance of landslide are obtained. (5) according to the characteristics of landslide induced by reservoir impoundment in Yingshui bank, the typical model is generalized. The variation of pore water pressure and shear stress in different periods when the water level of Yingshui reservoir rises and drops is numerically simulated. The relationship between shear stress and shear strength at different positions of sliding surface and the variation of slope stability with time are analyzed. The mechanism of landslide induced by impoundment of Yingshuian reservoir is revealed. Taking Zhaojiaban landslide as an example of backwater bank landslide, the variation of pore water pressure and stress during the rise and fall of reservoir water level is simulated and analyzed, and the mechanism of reservoir water storage inducing landslide in backwater bank is revealed. (6) selecting Sanmu landslide. Three typical cases of high slope in Nanyao village and high slope in Longshou village are analyzed numerically. The mechanism of forming new landslide caused by artificial excavation is explained. Taking Wangyaocun landslide as an example, the mechanism of old landslide resurrection caused by excavation is explained. Taking Yuanhezhuang landslide as an example, the variation of slope stress and shear strength after heaped load is analyzed, and the formation mechanism of landslide caused by surcharge is explained.
【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P642.22

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