澜沧江如美水电站左岸坝肩边坡开挖响应及稳定性评价

发布时间：2018-05-06 20:54

本文选题：如美水电站 + 左岸坝肩边坡　；参考：《成都理工大学》2017年硕士论文

【摘要】：随着我国西藏水电能源的开发,高山峡谷复杂地质环境条件下大型水电站的修建所带来的岩质高边坡的稳定性问题日益突出,如美水电站位于西藏自治区芒康县境内的澜沧江上游河段,拟建的心墙堆石坝最大坝高达315m,工程规模为一等大一型,是我国乃至世界上的高坝之一。如美水电站左岸坝肩边坡所在的河谷呈深“V”型,岩性为英安岩和花岗岩(左岸坝肩边坡开挖区以英安岩为主),左岸坝肩边坡具有地形陡峻、岩质坚硬、结构面发育、地表风化卸荷强烈和地应力复杂等特点,因此,对左岸坝肩开挖响应及稳定性的研究具有重大工程意义。本文以如美水电站左岸坝肩边坡为研究对象,通过边坡工程地质条件、岩体结构特征等研究,以定性分析和定量分析相结合的基本学术思想综合评价左岸坝肩边坡开挖条件下的变形破坏模式,基于变形破坏模式评价其开挖响应和稳定性。取得的主要研究成果如下:(1)根据前期坝址区地质调查资料,结合现场调查和复核,查明了边坡岩体结构特征。将左岸坝肩边坡发育的结构面按成因分为原生、构造和表生结构面,根据结构面分级标准将结构面分为Ⅲ级、Ⅳ级和Ⅴ级结构面。基于大量平硐调查资料,总结了左岸坝肩边坡岩体风化卸荷特征。(2)定性分析和定量分析相结合,分析了边坡潜在的变形破坏模式和变形破坏的边界。边坡变形破坏模式为由陡倾断层(或长大陡倾结构面)与中缓倾结构面组合形成的阶梯状滑移-拉裂或蠕滑-拉裂。左岸坝肩边坡开挖后存在三个潜在不稳定区域:其一是断层fp~(13-1)和高高程附近发育的缓倾外节理组成的潜在不稳定区域;其二为断层fp~(9-3)、fp~(9-4)和碎裂岩体界限组成的潜在不稳定区域;其三为断层带、岩脉和长大裂隙组合形成的浅表部潜在不稳定区域。(3)基于有限差分法和传递系数法,系统地研究了左岸坝肩边坡开挖卸荷条件下的稳定性。通过有限差分法得到边坡分级开挖条件下的应力、变形响应,通过传递系数法定量地分析了边坡潜在组合块体的稳定性。开挖影响边坡浅表部应力,其中最大主应力有减小→增大→减小的趋势。开挖引起最大约146.3cm的合位移,向坡外的最大变形约为73.6cm,向下的最大变形约为146.1cm,最大回弹值约为3.2cm。通过传递系数法得到了6个组合块体的稳定性系数,在天然工况下,由小断层fp~(9-5)和缓倾坡外节理控制的块体(块体2~4)稳定性系数较大,块体5的稳定性系数最小,但稳定性系数都大于1.2。(4)基于上述研究成果,左岸坝肩边坡开挖后主要影响范围是开口线以上岩体,由于断层的切割,开挖面以上的岩体失稳可能较大,是边坡治理的重点,要防止开口线以上的由断层控制的块体在开挖面剪出。同时,底部临时边坡的坡表会形成以岩脉为后缘,长大裂隙为底面的块体,应予以重视。
[Abstract]:With the development of Tibet hydropower energy, the stability of the high rock slope caused by the construction of the large hydropower station in the complex geological environment of the high mountain canyon is becoming more and more serious. For example, the main dam of the built heart wall rockfill dam is up to 315m in the upper reaches of the Lancang River in the Mangkam County of Tibet autonomous region. It is one of the high dams in our country and in the world, such as the deep "V" in the valley of the left bank abutment slope of the hydropower station. The lithology is the Angan rock and granite (the left bank abutment slope is excavated mainly by the Angan rock). The left bank abutment slope has steep terrain, hard rock, structural surface development, surface weathering stress and ground stress. Therefore, it is of great engineering significance to study the excavation response and stability of the left bank abutment. This paper takes the left bank abutment slope of the American hydropower station as the research object, through the study of the slope engineering geological conditions, the rock mass structure characteristics and so on, and comprehensively evaluate the left bank abutment with the basic academic thought of combining qualitative analysis with quantitative analysis. The deformation failure mode under the condition of slope excavation is based on the deformation failure mode to evaluate the response and stability of the excavation. The main achievements are as follows: (1) according to the geological survey data of the earlier dam site, the structural features of the rock slope are found out in combination with the site investigation and rechecking, and the structure surface of the left bank abutment slope is divided into the original form. The structure surface is divided into grade III, IV and v. Based on a large number of adit investigation data, the weathering and unloading characteristics of the rock mass in the left bank abutment slope are summarized. (2) the qualitative analysis and quantitative analysis are combined, and the potential deformation failure modes and the boundary of the deformation and failure are analyzed. The slope deformation and failure mode is a staircase slip - pull - pull or creep - pull crack formed by a steep dip fault (or a steep dip structure surface) and a medium dip structure surface. There are three potential unstable regions after the excavation of the left bank abutment slope: one is the potential unstable region formed by the slow DIP joint developed near the fault fp~ (13-1) and high elevation. The second is the potential unstable region of the fault fp~ (9-3), fp~ (9-4) and fractured rock mass boundary, and the third is the potential unstable region formed by the fault zone, the rock vein and the large fissure combination. (3) the stability of the slope under the unloading condition of the left bank abutment slope is systematically studied based on the finite difference method and the transfer coefficient method. The finite difference is carried out through the finite difference. The stress, deformation response and the stability of the potential block of the slope are quantitatively analyzed by the transfer coefficient method. The stress of the shallow surface of the slope is affected by the excavation. The maximum principal stress has the tendency to decrease, increase and decrease. The maximum 146.3cm displacement is caused by the excavation, and the maximum deformation is about the slope outside the slope. For 73.6cm, the maximum downward deformation is about 146.1cm, the maximum rebound value is about 3.2cm. through the transfer coefficient method, the stability coefficient of 6 block bodies is obtained. Under natural conditions, the stability coefficient of block (block body 2~4) controlled by small fault fp~ (9-5) and gently inclined slope is larger, and the stability coefficient of block 5 is the smallest, but the stability coefficient is all More than 1.2. (4) based on the above research results, the main influence range after the excavation of the left bank abutment slope is the rock mass above the opening line. Because of the cutting of the fault, the instability of the rock mass above the excavation face is likely to be larger. It is the key point of the slope treatment. The formation of rock mass should be regarded as the trailing edge of the dike and the bottom of the growth fissure.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV223

【参考文献】