三峡库区李家湾滑坡复活机理及其稳定性研究

发布时间：2018-06-19 03:05

本文选题：降雨 + 库水位下降　；参考：《成都理工大学》2015年硕士论文

【摘要】：李家湾滑坡位于重庆市长寿区凤城镇三洞村桃花溪右岸斜坡一带,区内降雨丰富,且降雨量大,受库水位涨落和降雨的影响,研究区的变形有进一步发展的趋势,考虑到研究区内分布有大量民房,居住有居民和企业职工共368人,且长寿区供水管道在此通过,该供水管道承担了长寿区大于5万户居民的日常生活用水任务,若滑坡复活失稳,将直接威胁到居民和企业职工的生命财产安全,影响长寿区居民正常的日常生活,因此研究老滑坡的复活机制并对其稳定性进行评价具有重要的现实意义。本文通过对李家湾滑坡的地质结构、水文地质特征,滑坡强-弱变形区的发育特征的分析,揭露滑坡的复活机制及影响因素;运用Geo-studio软件对滑坡的主变形区进行渗流场的数值模拟,得到不同工况下的浸润线变化、孔隙水压力等值线图,评价其对滑坡稳定性的影响,在此基础上,采用灰色关联度理论研究不同抗剪强度指标、降雨量大小及不同库水位高程对滑坡稳定性的敏感强度,最后采用FLAC3D数值模拟对主变形区的应力、应变场、塑性区进行分析研究,取得了如下主要成果。(1)李家湾滑坡是在滑坡的内在和外在条件的作用下发生的,其中内部条件包括地形地貌、地质构造、坡体结构特征,外在条件主要为降雨和河流下切。其中砂泥岩软硬互层的坡体结构特征,坡体易沿平缓的软弱夹层向坡前临空方向产生压致拉裂,在暴雨条件下,坡体在静水压力和空隙水扬压力的联合作用下发生滑动。(2)李家湾滑坡的复活区分为3个强变形区,1个弱变形区。李家湾滑坡的复活由库水位的变动和降雨引起,其中降雨是滑坡复活的主要诱发因素,其对滑坡的影响主要表现在:雨水入渗降低土体的抗剪强度,增加坡体的自重,从而增大坡体的下滑力。从非饱和土力学原理,雨水渗入滑坡体以后,会使滑坡体内的基质吸力减小,有效应力降低,同时,软化泥化滑带土,使粘土矿物发生水化作用导致粘聚力下降,从而改变坡体的力学性能。(3)利用Geo-studio软件中的Seep模块模拟库水位下降对滑坡前缘渗流场的情况可知,库水位下降到一段时间后,滑坡前缘土体浸润线明显滞后于库水位的下降速率,浸润线高于水位线,而远离库水位的坡顶及滑坡上部,基本不受库水的影响,库水位下降速率越快,浸润线滞后越严重,导致的水头差越显著,其形成的向下渗流力也就越大,对滑坡的稳定性影响越大。(4)库水位以每天下降0.6m和1.2m的过程中,李家湾滑坡的稳定状况处于稳定和基本稳定之间;而叠加3d暴雨强度85mm/d的情况,李家湾滑坡处于基本稳定~欠稳定状态。(5)通过FLAC3D软件对四种工况下的滑坡稳定性的应力、应变场及剪切塑性区的数值模拟分析发现,在工况I下,库水位在下降过程中,滑坡前缘局部出现拉应力集中带,滑坡位移变化只发生在前缘附近,剪应变增量集中在岩土分界面上,滑坡的变形破坏主要沿着主滑动面破坏;在工况III和IV下,前缘拉应力分布范围有所增大,中后部局部范围有拉应力分布,剪切塑性区在坡体表层有所延伸,并向深部发展。(6)通过分析李家湾滑坡三期治理工程的治理效果,根据《三峡库区三期地质灾害防治工程设计技术要求》的相关规定,提出李家湾滑坡治理工程的补强措施建议,在滑坡前缘高程177m布置一排26根抗滑桩支挡工程,在滑坡左侧高程200m布置一排17根抗滑桩支挡工程,在滑坡后缘高程257m附近设置截排水工程。
[Abstract]:Lijia Bay landslides are located in the right bank slope of the three Dong village, Fengcheng village, Changshou District, Chongqing. The rainfall is abundant and the rainfall is large. The deformation of the study area is further developed by the fluctuation of the reservoir water level and rainfall. It is considered that there are a large number of houses in the study area, 368 people living in the residential and enterprise workers, and the longevity area. When the water supply pipeline is passed, the water supply pipeline bears the daily living water task of more than 50 thousand households in the long life area. If the landslide resurrection is unstable, it will directly threaten the safety of the lives and property of the residents and the workers and workers, and affect the normal daily life of the residents in the longevity area. Therefore, the resurrection mechanism of the old landslides is studied and the stability of the landslides is evaluated. It is of great practical significance. Through the analysis of the geological structure, hydrogeological characteristics and the development characteristics of the strong and weak deformation zone of the Lijia Bay landslide, this paper reveals the resurrection mechanism and the influencing factors of the landslide, and uses the Geo-studio software to simulate the seepage field of the main deformation area of the landslide, and obtains the change of the infiltration line under different working conditions. The pore water pressure contour map is used to evaluate the effect of the pore water pressure on the stability of the landslide. On this basis, the grey correlation degree theory is used to study the sensitive strength of the different shear strength indexes, the rainfall size and the reservoir water level height to the landslide stability. Finally, the FLAC3D numerical simulation is used to analyze the stress, strain field and plastic zone in the main deformation zone. The main results are as follows. (1) the Lijia Bay landslide occurred under the internal and external conditions of the landslide. The internal conditions included topography, geomorphology, geological structure, and slope structure characteristics, and the external conditions were mainly rainfall and river cutting. The slope body structure of the soft and hard interbedded sand mudstone is easy to be soft and weak. Under the rainstorm condition, the slope slides under the combined action of the hydrostatic pressure and the air gap pressure. (2) the resurrection of the Lijia Bay landslide is divided into 3 strong deformation zones and 1 weak deformation zones. The resurrection of the Lijia Bay landslide is caused by the change of the reservoir water level and the rainfall, among which the rainfall is the resurrection of the landslide. The main factors that induce the landslide are as follows: the rain infiltration reduces the shear strength of the soil, increases the weight of the slope, and thus increases the sliding force of the slope. After the infiltration of the unsaturated soil mechanics principle, the rain infiltration into the landslide body will reduce the matrix suction in the landslide body, reduce the effective stress, and soften the mud and slide the soil to make the clay stick. The hydration of soil minerals leads to the decrease of cohesive force and change the mechanical properties of the slope. (3) using the Seep module in Geo-studio software to simulate the seepage field in the front of the landslide, it is known that the soil infiltration line of the front of the landslide is obviously lagging behind the decline rate of the reservoir water level and the infiltration line is high after the reservoir water level drops to a period of time. At the water level line, the top of the slope and the top of the landslide far away from the reservoir water level are basically not affected by the reservoir water. The faster the decline rate of the reservoir water level is, the more serious the lag line is, the more significant the head difference is, the greater the downward seepage force is, the greater the effect on the stability of the landslide. (4) the reservoir water level is in the process of decreasing 0.6m and 1.2m every day, Li Jia Wan. The stability of the landslide is between the stability and the basic stability, and the Lijia Bay landslide is in the basic stable and unstable state when the 3D rainstorm intensity is 85mm/d. (5) the stress of the landslide stability, the strain field and the shear plastic zone of the four conditions are simulated by the FLAC3D software, and the reservoir water level is decreased under the working condition of I. During the process, the tensile stress concentration zone appears in the front of the landslide. The change of the landslide displacement only occurs near the front edge, and the shear strain increment concentrates on the geotechnical interface. The deformation and failure of the landslide is mainly destroyed along the main sliding surface. Under the working condition III and IV, the distribution range of the tensile stress in the front edge is increased, and the local range of the middle and rear parts has the tensile stress distribution and the shear stress distribution. The plastic zone extends in the surface of the slope and develops to the deep. (6) through the analysis of the treatment effect of the three period treatment project of the Lijia Bay landslide, according to the relevant regulations of the design technical requirements of the three geological disaster prevention and control engineering in the Three Gorges Reservoir area, the suggestion of strengthening the reinforcement measures of the Lijia Bay landslide control project is put forward, and a row of 26 of the elevation 177m of the landslide front is arranged in a row of 26. A row of 17 anti slide piles are arranged at the elevation 200m of the left side of the landslide, and a drainage project is set up near the elevation 257m of the rear edge of the landslide.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.22

【参考文献】