四川珙县漂水岩水库工程垮山湾滑坡形成机制及稳定性研究

发布时间：2018-05-19 12:10

本文选题：垮山湾滑坡 + 滑坡分区　；参考：《成都理工大学》2015年硕士论文

【摘要】：漂水岩水库坝基开挖施工过程中,探明滑坡体坡脚恰好位于设计面板堆石坝坝肩部位,而开挖前在库岸区内未见该滑坡体明显的滑动迹象。滑坡地形地貌较平缓,且岩层倾角较缓,地表裂缝不甚发育而易被忽视。坡体由还建公路向河床逐级开挖过程中,坡体前缘出现的变形愈加明显。若对滑坡采取的防治处理措施不足,在将来可能影响坝体稳定,轻则导致库容减小,重则坝体失稳。为保障坝体的稳定和水库的正常运行,本文立足于区域及工程区基本地质条件,从滑坡变形特征、变形监测数据、岩土体物理力学性质出发,结合过程机制分析法、理论计算法及UDEC、FLAC3D、Geostudio等数值模拟手段分析研究滑坡形成机制、前缘局部变形破坏机制以及滑坡在前缘开挖临空后、筑坝回填、降雨及库水位升降等工况下的整体及局部稳定性和应力应变的变化特征,主要取得了以下成果及认识:(1)滑坡体最大厚度约30m,方量约250×104m3,属大型滑坡。据滑坡变形特点与工程建筑物、边坡开挖等的关系,将滑坡分为I1变形破坏亚区、I2变形亚区和下游侧II相对稳定区。其中I1区方量达35×104m3,前缘局部坍塌,暴雨时趾板有水渗出;滑坡I2区开挖前后坡体无明显变形,相对I1区稳定;II区较稳定,无明显变形。据现场地质踏勘及滑坡前缘开挖揭露,“似层状”岩层在坡体中十分发育,采用钻探、钻孔电视手段及现场物理力学试验,探明坡体多处软弱夹层、挤压带发育且存在架空现象。上游边界拉裂缝及后缘拉陷槽发育,坡脚开挖揭露剪出口,暴雨后坡体有多处渗水口,河床未开挖前滑带隐藏。(2)滑坡体原为志留系软硬互层状岩体,缓倾坡外,层间错动带或软弱夹层较发育。滑坡形成历史分析表明滑坡主要经历了河谷下切和坡体蠕滑、压致拉裂面由下至上延伸、斜坡顺层滑动和河床再造四个演变阶段。UDEC数值模拟再现了滑坡早期在自重作用下沿下伏软弱结构面、软弱夹层变形破坏的过程。据坡体后缘拉陷槽和陡倾结构面特征、坡体开挖揭露的坡体结构及拉张裂隙和“阶状”裂隙等变形特征、数值模拟结果,综合判定滑坡变形破坏模式为“滑移—压致拉裂”。(3)监测数据显示,开挖使I1区变形,随着开挖深度的增大变形逐渐加剧,暴雨条件下局部坡体发生垮塌。滑坡区位于向斜核部向两翼转折部位,坡体后缘、下游侧陡倾结构面发育,为开挖条件下滑坡前缘I1区的局部变形破坏提供了构造条件。对I1区逐级开挖过程的现场勘察、监测、FLAC3D数值模拟表明:坡体在前缘临空、内部残留的软弱夹层及软弱结构面泥化、软化作用的共同影响下局部贯通,上部坡体发生拉裂,该区在降雨或施工水流作用下发生“蠕滑—拉裂”变形,具牵引式特征,对降雨等水的作用较敏感。(4)采用极限平衡法对滑坡稳定性分析表明:滑坡整体在各工况条件下处于基本稳定~稳定状态,滑坡II区稳定性较高,I1区稳定性低于其他分区。结合SEEP/W与SLOP/W对滑坡渗流场及稳定性进行研究,滑坡在降雨时前缘I1区近坡表部位水位抬升稍高于坡体内部,库水位升降条件下坡体内部浸润线“滞后”于前缘坡脚处浸润线的变化。滑坡整体稳定性受开挖、筑坝回填、降雨及蓄水等影响稍小,处于基本稳定~稳定状态;滑坡I1区稳定性受各工况影响较大,处于不稳定~欠稳定状态。降雨、库水升降对滑坡I1区稳定性影响大。(5)采用有限元软件Geostudio中SEEP/W与SIGMA/W模块对各工况下坡体渗流场、应力场耦合分析,发现与天然状态相比,在滑坡前缘开挖后、筑坝回填以及库水位升降条件下坡体剪应力主要集中在I1区下部,坡脚趾板、462m马道部位水平方向位移最为显著。
[Abstract]:During the construction process of the dam foundation excavation of the bleeyan reservoir, it is proved that the foot of the landslide body is just located at the part of the dam shoulder of the design face rockfill dam, and there is no obvious sign of slide in the bank area before the excavation. The landform of the landslide is relatively gentle, and the dip angle of the rock layer is slow, and the surface cracks are not very well developed and easily ignored. In the process of progressive excavation, the deformation of the front edge of the slope becomes more and more obvious. If the prevention and treatment measures for the landslide are insufficient, it may affect the stability of the dam in the future, the light result in the decrease of the capacity of the reservoir and the instability of the dam body. In order to ensure the stability of the dam body and the normal operation of the reservoir, this paper stands in the basic geological conditions of the region and the engineering area, and changes from the landslide to the landslide. The form characteristics, deformation monitoring data, physical and mechanical properties of rock and soil, process mechanism analysis method, theoretical calculation method and UDEC, FLAC3D, Geostudio and other numerical simulation methods are used to analyze the mechanism of landslide formation, the mechanism of local deformation and failure of the front edge, and the backfilling of the dam, the rainfall and the rise and fall of the reservoir water level after the front edge of the excavation. The following achievements and understanding are obtained: (1) the maximum thickness of the landslide body is about 30m and the square amount is about 250 x 104m3, which is a large landslide. According to the relationship between the landslide deformation characteristics and the engineering buildings and the slope excavation, the landslide is divided into the I1 deformation subregion, the I2 deformation subregion and the downstream side II relative. In the stable area, the square of I1 area is 35 x 104m3, the front edge is partially collapsed, and the toe plate has water exudation when the rainstorm is torrential. There is no obvious deformation in the slope body before and after the excavation of the landslide I2 area, and the relative I1 area is stable. The II area is more stable and has no obvious deformation. According to the site geological exploration and the excavation of the landslide front, the "like layer" rock is very well developed in the slope body, using drilling and drilling electricity. According to the method and field physical and mechanical test, it is found that many weak interbeds in the slope, the extruding zone is developed and there are aerial phenomena. The upstream boundary pull cracks and the trailing edge trench grooves are developed, the slope foot excavation exposes the shear exit. The slope body has many seepage ports and the river bed before the excavation is excavated. (2) the landslide body is the Silurian soft and hard interbedded rock mass, gently tilting. The historical analysis of landslide formation shows that the landslide mainly experienced the downfall of the valley and the creep of the slope, the extension of the crack surface from the bottom to the top, the four stages of the.UDEC numerical simulation of the slope slide and the river bed reengineering. The deformation and failure process of the interlayer. According to the characteristics of the subsidence trough and the steep structure surface of the rear edge of the slope, the deformation characteristics of the slope body, such as the structure of the slope body and the tension fracture and the "order" fissure, are revealed. The numerical simulation results show that the deformation and failure mode of the landslide is "sliding compression cracking". (3) the monitoring data shows that the excavation makes the deformation of the I1 region deformed. The deformation of the excavation depth increases gradually, and the local slope collapse under the condition of heavy rain. The landslide area is located at the turning part of the two wings at the syncline core, the rear edge of the slope body and the steep slope of the downstream side are developed, which provides a structural strip for the local deformation and failure in the I1 area of the front edge of the landslide under the condition of excavation. The FLAC3D numerical simulation shows that the slope body is on the front edge, the internal residual weak intercalation and the weak structural surface are muddy, and the softening effect is affected by the joint under the influence of softening, and the upper slope is cracked. In this area, the deformation of "creep and crack" occurs under the action of rainfall or construction flow, which has the characteristic of traction and is more sensitive to rainfall and water. (4) The stability analysis by the limit equilibrium method shows that the landslide is stable in the basic stable state under all working conditions, the stability of the landslide II zone is higher and the stability of the I1 region is lower than that of other areas. The seepage field and stability of the landslide are studied with SEEP/W and SLOP/W, and the water level of the near slope at the front edge of the front edge of the front edge of the landslide is raised by the landslide. Slightly higher than the interior of the slope body, the infiltration line inside the slope body is lagging behind the change of the infiltration line at the foot of the front slope. The overall stability of the landslide is excavated, the dam is filled, the rainfall and the water storage are slightly affected, and the stability is in the basic stable state. The stability of the landslide I1 area is greatly influenced by various working conditions, and it is in the unstable under stable state. Rainfall, reservoir water lifts have great influence on the stability of the landslide I1 area. (5) using the finite element software Geostudio SEEP/W and SIGMA/W module to analyze the seepage field of the slope body and the stress field coupling analysis of each working condition, it is found that, compared with the natural state, after the excavation of the front edge of the landslide, the shear stress of the dam is mainly concentrated under the I1 area. The horizontal displacement of the 462m toe road is the most significant.
【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

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