【作者】 顾涛；

【导师】 沈军辉；

【作者基本信息】 成都理工大学 ， 地质工程， 2010， 硕士

【摘要】 两河口水电站是雅砻江中下游控制性水库工程,坝址区位于雅砻江与鲜水河汇合口下游约0.6~3.6km的河段上,拟建心墙堆石坝坝高达295m。坝肩边坡断裂裂隙较发育,地质条件复杂,心墙开挖量较大,坝肩边坡稳定性将对工程施工带来潜在危害。因此,研究坝肩边坡的稳定性,进而提出相应的支护措施,对确保工程施工安全具有重要的实际意义。本文在分析工程区基本地质条件、斜坡岩体结构特征、变形破裂迹象等研究的基础上,对坝肩边坡的变形破坏模式进行了分析,采用定性评价、极限平衡计算、块体稳定性计算、Flac3D和Plaxis软件进行数值模拟计算,分层次系统地评价了坝肩边坡稳定性,获得了如下主要认识:(1)坝肩边坡主要由三叠系上统两河口组地层组成,岩性主要为变质砂岩与板岩呈不等厚互层,斜坡总体为陡倾下游的横向坡。岩体中断裂、裂隙发育,其中规模相对较大的Ⅲ级、Ⅳ级结构面一般顺层发育,其中左岸陡倾下游偏坡外产出,右岸则陡倾下游偏坡内产出。(2)两岸节理裂隙发育程度具一定差异,其中左岸以①、②、⑥、④、③组裂隙较发育,斜坡的变形破坏方式主要为楔形滑移拉裂型;右岸以①、②、④、⑦、③组裂隙较发育,斜坡的变形破坏方式主要为滑移拉裂型或滑移压致拉裂型。局部存在旋转滑移拉裂型及冒落式滑塌型破坏模式。(3)坝肩斜坡除发育三个对坝肩边坡稳定性起重要影响作用的卸荷松弛变形体外,斜坡的变形破裂程度整体较弱。左坝肩发育Ⅰ、Ⅱ号楔形滑移拉裂型卸荷拉裂岩体,右坝肩发育滑移拉裂型卸荷拉裂岩体。稳定性计算结果表明,卸荷拉裂岩体整体处于稳定-基本稳定状态。(4)除左岸心墙部位工程边坡开挖量较大外,边坡开挖主要沿自然边坡坡表进行,对边坡的扰动较小。定性分析和稳定性计算表明,工程边坡整体稳定性较好,仅在开挖面揭露的断层、挤压错动带和长大节理出露处出现局部失稳块体。数值模拟结果表明,工程开挖对坝肩边坡整体稳定性影响不大,总体来讲,开挖引起的应力增量和位移增量均较小,未改变边坡总体的应力平衡状态,仅在开挖面坡脚、断层、挤压带等控制性结构面附近以及强卸荷底线以上产生相对明显的应力和位移集中分布现象,在相应部位出现拉应力区和塑性区,可能出现局部失稳块体。(5)根据稳定性评价结果,对坝肩边坡不同部位提出了相应的支护措施,对不稳定块体主要采用挂网喷浆及加强锚杆支护,对规模相对较大的潜在不稳定块体主要采用预应力锚索支护。更多还原

【Abstract】 Located in the about 0.6 ~ 3.6km in the downstream of the confluence where Yalong River and Xianshui River flow together, Liang he-kou hadroelectric power station is an important reservoir to control the middle and lower reaches of Yalong River with the proposal to construct a core rockfill dam being up to 295m. As the fault of abutment slope is more developed and geographical conditions are more complex, potential danger of excavating large amount of corewall will be increased, which implies that slope stability of abutment construction will bring potential hazards to the construction. Thus, it is of great significance to study abutment stability and procceed to make appropriate measures to ensure construction safety.Based on the basic geological conditions, structural features of rocks on the slope as well as the signs of deformation and fracture, this thesis analyses the abutment slope failure modes and evaluate abutment slope stability with a hierarchical system, by adoption of qualitative assessment, ultimate balance calculation, block stability calculation and numericak simulation with Flac3D Plaxis softwares. Finally, this thesis gains access to the following key understandings:(1) The abutment slope is generally horizontal, sloping steeply towards the downsteam. Rock fracture existed, crack also develops, of which relatively larger scale of gradeⅢ,Ⅲ-level structure has a general plane of bedding including that left bank of steep slpoe is outside the output of the downstream, right bank of the steep slopes is within the output of the downstream side.(2) Developmemt of cross joints and fractures varies to some extent, among which①,①,①,①,①groups of fissures are more developed in the left bank. The main mode of eformation and failure of the slope is the wedge-shaped sliding fracturing. In the right bank,①,①,①,①and①groups are more developed, the main mode of deformation and failure of the slope is slip or slide tension type pressure-induced fracturing. Local rotated sliding fracturing and falling-type slump-type failure mode existed in some parts as well.(3) Abutment slope nurtures three pairs of deformed parts to unload and relax which plays an important role in keeping abutment slope stable. In addition to this, degree of slope deformation and fracture is generally weak. In the left abutment slope, No.Ⅰ,Ⅰdevelop the wedge sliding type rock which discharges Hera crack tension. Whereas in the right abutment slope, unloaded Hera type tension block is developed. Stability results show that the dumping mass stable Hera remains stable, basically stable.(4) The slope excavation is conducted along the natural slope of the main slope of the table in order to lessen the disturbance, except that there is a large amount of site excavation works of core wall in the left bank. Qualitative analysis and stability calculations reaveal that the overall stability of the slope remains better, only to find unstable blocks in the faults of excavation face, squeeze fault zone and mature exposed sections.Numerical simulation results demonstrate that the excavation of the dam has little effect on slope stability. Generally speaking, incremental stress caused by excavation and displacement increment are so small that it is unable to change the overall slope of the stress state of equilibrium. Phenomenons of relatively obvious concentration of stress and displacement distribution only occure near controlled-structure surface such as slope in the excavation, fault, extrusion and above the unloading bottom line. It is likely to happen that partial loss stable blocks exist in in the tensile stress parts and plastic zones of corresponding parts as well.(5) According to the stability of the evaluation results, this thesis proposes corresponding support measures in different parts of the abutment slope such as hanging block spray and strengthening the bolting rearding the unstable parts, adopting prestressed anchor support as the main measure when addressing potential unstable blocks of large size.更多还原