雅砻江牙根二级水电站缆机平台边坡稳定性评价及支护措施研究

发布时间：2018-05-07 07:14

本文选题：牙根水电站 + 缆机平台　；参考：《成都理工大学》2014年硕士论文

【摘要】：拟建的牙根二级水电站是雅砻江中游规划的第三个梯级电站，设计重力坝最大坝高130m，缆机平台边坡开挖最大高度愈100m。边坡岩体断层、裂隙发育，尤其是缆机平台边坡发育一组顺坡缓倾小断层，边坡在其控制下变形强烈，浅表岩体松弛拉裂，稳定性较差，工程开挖边坡存在安全隐患。因此，评价缆机平台边坡的稳定性，并且研究相应的支护措施，对确保工程安全施工和运行具有重要的实际意义。本文在查明边坡赋存的地质环境条件及边坡的工程地质特性基础上，对边坡岩体结构及变形破裂特征进行研究，确定了边坡的变形破坏模式，在此基础上，建立边坡变形破坏机制的模型，采用地质分析和刚体极限平衡法分别对边坡稳定性进行定性和定量评价，采用FLAC3D对开挖后（未支护）边坡进行模拟，对工程边坡的支护设计进行研究，采用MIDAS/GTS对支护后边坡进行模拟，对边坡稳定性作出全面综合的判断。通过以上工作，取得了以下主要认识：（1）缆机平台边坡岩体结构发育，发育有Ⅱ、Ⅲ、Ⅳ、Ⅴ级结构面，其中Ⅲ、Ⅳ、Ⅴ级结构面为缆机平台边坡范围内的主要结构面。Ⅱ级结构面发育有两条；Ⅲ级结构面为地表断层及平硐出露的部分较大规模的断层、挤压带，主要有三组优势结构面：①NE走向陡倾结构面，②近EW走向陡倾结构面，③NW走向缓倾角结构面；Ⅳ级结构面为平洞内断层和挤压带，大部分为陡倾角断层；Ⅴ级结构面以NW-NNW向为主。（2）由缆机平台边坡坡表及平硐变形破坏特征，，结合结构面发育规律，分析可知边坡控制性结构面为一组NW走向倾NE的缓倾角结构面，陡倾角优势结构面为NWW走向结构面，缓倾角结构面可作为底滑面，陡倾角结构面作为后缘拉裂面发生滑移-拉裂破坏， NE走向陡倾结构面和近EW走向陡倾结构面可作为边坡变形破坏的侧向控制面，故边坡失稳模式为滑移-拉裂破坏。需要特别说明的是F18作为陡倾角断层，出露于缆机平台边坡坡表，由于其自身带宽为12m，坡表松散物堆积，且缆机平台边坡坡表为Ⅴ类岩体，极有可能与缓倾角结构面组合，沿强卸荷底界发生弧形滑移-拉裂破坏。（3）边坡稳定性计算表明：自然边坡在天然工况下稳定性系数较好，边坡整体处于稳定状态；在暴雨工况下，边坡稳定性也相应下降，但对边坡稳定性影响不大，边坡整体仍处于基本稳定状态；在地震工况下，边坡稳定性处于极限平衡状态～基本稳定状态。开挖后工程边坡的稳定性系数略微下降，但在天然工况下边坡整体基本稳定状态；在暴雨工况下，计算结果较天然状态下会相应降低，但对边坡稳定性影响不大，边坡整体仍处于基本稳定状态；在地震工况（偶然状况）下，边坡稳定性处于极限平衡状态～基本稳定状态。局部稳定性较差，多处于不稳定状态。（4）边坡开挖后（未支护）数值模拟分析表明：总位移随着开挖过程呈小幅度增加趋势，开挖后缓倾角结构面出露地表，剪应变增量集中于缓倾角坡表位置，边坡坡表上部为Ⅴ类岩体，塑性区主要集中于这一区域。（5）通过对边坡稳定性的定性定量评价，边坡支护措施设计研究如下：缆机平台边坡发育的一组缓倾坡外结构面为边坡稳定的控制性因素，采用预应力锚索进行支护；F18作为陡倾角断层，带宽宽度较大，袋内松散体堆积，坡表为Ⅴ类岩体，出露于缆机平台工程边坡，具有其特殊性，故单独考虑采用框架锚索对其进行支护；工程边坡整体采用素喷混凝土措施；根据工程边坡条件，工程边坡外围布置截水沟，顺工程边坡布置排水沟，每级马道布置截水沟。（6）通过对支护后的边坡进行数值模拟，分析结果表明支护措施满足边坡稳定性及安全性要求。
[Abstract]:The proposed two cascade hydropower station is the third cascade hydropower station planned in the middle reaches of Yalong River. The maximum dam height of the gravity dam is 130m. The maximum height of the slope excavation of the cable platform slope is 100m., the fracture is developed, especially in the slope of the cable plane, a group of slope gently inclined small faults are developed. The slope is strongly deformed under the control of the slope, and the shallow rock mass is loose. The stability of the excavation slope has a hidden safety hazard. Therefore, it is of great practical significance to evaluate the stability of the slope of the cable platform and to study the corresponding support measures to ensure the safety of the construction and operation of the project.
On the basis of geological environment conditions and engineering geological characteristics of slope, the characteristics of rock mass structure and deformation fracture of slope are studied, and the deformation and failure mode of slope is determined. On this basis, the model of slope deformation and failure mechanism is established, and the slope stability is stabilized by the ground quality analysis and the rigid body limit equilibrium method. Qualitative and quantitative evaluation, using FLAC3D to simulate the slope after excavation (unsupported), study the support design of the slope, simulate the slope after the support with MIDAS/GTS, and make a comprehensive and comprehensive judgement on the slope stability.
(1) the rock mass structure of the slope of the cable machine platform is developed, and there are II, III, IV and V level structural planes. Among them, the structure surface of grade III, IV and V is the main structure in the slope range of the cable platform. There are two development of the second grade structure surface, and the third grade structure surface is the surface fault and the large scale fault in the adit and the extrusion zone, mainly with three groups of advantages junctions. Construction surface: (1) NE to steeply dipping structural surface, (2) nearly EW to steeply dipping structural surface, (3) NW to slow dip angle structural plane, and grade IV structure surface is flat hole and extrusion zone, most of which are steep dip faults, and grade V structure surface is dominated by NW-NNW direction.
(2) according to the deformation and failure characteristics of the slope slope and the adit of the cable platform and the development law of the structure surface, it is concluded that the controlled structural face of the slope is a group of slow dip angle structures with NW heading to NE, and the steep inclination advantage structure is NWW to the structure surface, and the gentle dip angle structure can be used as the bottom sliding surface and the steep angle structure is slippery as the trailing edge of the rear edge. It is necessary to explain that F18 is a steep dip fault, which shows that F18 is a steep dip fault, which is exposed to the slope of the slope of the cable platform, which is 12m in its own bandwidth and loose in the slope, and cable. The slope surface of the platform slope is a class V rock mass, which is most likely to be combined with the gently inclined structural plane.
(3) the calculation of slope stability shows that the stability coefficient of natural slope is better under natural condition, the whole slope is in stable state, and the slope stability is also reduced under the heavy rain condition, but it has little influence on the slope stability, the whole slope is still in the basic stable state, and the slope stability is in the limit equilibrium under the condition of earthquake. State to basic stable state.
The stability coefficient of the slope is slightly decreased after the excavation, but the whole slope is basically stable under the natural condition. Under the heavy rain condition, the calculation results will be lower than the natural condition, but the slope stability has little influence, the slope is still in the basic stable state; under the earthquake condition (accidental condition), the slope stability place In the limit equilibrium state to the basic stable state. The local stability is poor, and most of them are unstable.
(4) the numerical simulation analysis of the slope after excavation (unsupported) shows that the total displacement increases with the excavation process, the surface of the slow dip structure is exposed and the shear strain increment concentrates on the position of the gentle dip slope surface. The upper part of the Bian Popo table is type V rock mass, and the plastic zone is mainly concentrated in this area.
(5) through the qualitative and quantitative evaluation of slope stability, the design and study of slope support measures are as follows: a group of gentle slope outside structural surfaces developed on the slope of the cable platform is the control factor of the slope stability, the prestressed anchor cable is used to support the slope, and F18 as a steep dip fault, the width of the bandwidth is larger, the loose bulk in the bag is accumulated and the slope table is type V rock mass. When the slope is exposed to the cable platform engineering slope, it has its special characteristics, so the frame anchorage cable is used to support the slope. The engineering slope is composed of plain spraying concrete measures, the cutting ditch is arranged in the periphery of the engineering slope, the drainage ditch is arranged in the slope of the engineering slope, and the trench is arranged at each grade horse road.
(6) through the numerical simulation of the slope after supporting, the analysis results show that the supporting measures meet the stability and safety requirements of the slope.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV223

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