澜沧江苗尾水电站右坝肩边坡倾倒岩体开挖变形响应及稳定性研究

发布时间：2018-10-26 14:10

【摘要】：在建澜沧江苗尾水电站位于云南省云龙县境内，拟建坝型初拟为硅面板堆石坝，设计坝高138m，正常蓄水位1408m，，库容7.01亿m3，总装机容量120×104KW。坝址区地质环境复杂，岩体倾倒变形现象发育，在施工开挖过程中，出现了一系列的变形现象，倾倒岩体边坡的稳定性对于右坝肩边坡施工期及运营期意义重大。因此，本文以澜沧江苗尾水电站右坝肩边坡为研究对象，采用地质分析法、数值模拟分析法和刚性极限平衡法等，深入分析和研究了右坝肩边坡开挖后的变形响应特征并对其稳定性进行了评价。通过较为系统的研究分析，本文主要取得了以下的研究成果和基本认识： （1）根据前期地质勘察资料，结合施工期地质条件的现场调查和复核，研究了右坝肩边坡岩体结构特征，结果表明：右坝肩边坡坡脚以软岩为主，中部及中上部为软硬岩互层组合，边坡范围内发育的结构面主要为Ⅲ2、Ⅲ3、Ⅳ和Ⅴ级结构面。 （2）根据在现场对坝基岩体以及边坡倾倒岩体的岩体结构精细描述，分析了边坡倾倒变形岩体与坝基基岩之间的区别，优势结构面发育特征以及对边坡稳定性的控制作用。与此同时，根据平硐编录并结合前期研究成果，建立了右坝肩边坡倾倒变形强烈程度地质模型。 （3）通过对边坡开挖离散元数值模拟，分析了边坡从开挖直至失稳的变形发展过程和开挖引起的不同高程坡体变形响应特征，边坡坡脚部位的开挖造成开口线部位岩体变形，且为其上部岩体提供变形空间，从而导致边坡倾倒岩体变形持续发展，自开口线向边坡中上部变形逐渐增强，尤其表层岩体受倾坡外结构面的影响，倾倒变形可能转化为滑移-拉裂的变形破坏模式。 （4）通过有限差分FLAC3D数值模拟分析了边坡开挖前、开挖后以及现有支护条件下的稳定性状况，结果表明：原始边坡的变形主要集中在边坡A类岩体中，开挖后在坡体内部以及中上部坡表出现了拉应力集中区，变形向内部发展，扩展至B1类岩体中部，稳定性受到影响；边坡现有支护基本能抑制由于开挖引起的变形。 （5）采用极限平衡法对边坡开挖后现有支护条件下进行了不同工况的稳定性计算，计算结果表明：边坡在现有支护条件下稳定性系数基本满足相关规范要求，但在蓄水+地震的极端工况下，稳定性系数降至1.1以下，处于基本稳定状态。 （6）从边坡变形监测数据分析结果来看，边坡前期变形主要出现在坡的中上部，特别是上部变形较大，自上而下逐渐减小，边坡的坡表变形较大，沿坡体深度递减较快，自坡表向坡内逐渐减小。开口线以上支护实施以后，边坡变形趋于收敛稳定。
[Abstract]:The Miaowei Hydropower Station of Lancang River is located in Yunlong County, Yunnan Province. The proposed dam type is originally designed as a silicon face rockfill dam with a design height of 138m, a normal water level of 1408m, a storage capacity of 701 million m3 and a total installed capacity of 120x104KW. The geological environment of the dam site is complex and the phenomenon of rock mass toppling deformation is developed. During the construction and excavation a series of deformation phenomena occur. The stability of the toppling rock slope is of great significance for the construction and operation period of the right abutment slope. Therefore, the right abutment slope of Miaowei Hydropower Station in Lancang River is taken as the research object. Geological analysis method, numerical simulation analysis method and rigid limit equilibrium method are used in this paper. The deformation response characteristics of right abutment slope after excavation are analyzed and studied and its stability is evaluated. Through systematic research and analysis, this paper has mainly obtained the following research results and basic understanding: (1) according to the data of early geological survey, combined with the field investigation and review of geological conditions during the construction period, The rock mass structure characteristics of the right abutment slope are studied. The results show that the soft rock is dominant in the foot of the slope at the right abutment side, the soft and hard rock interbedded assemblage in the middle and upper part of the slope, and the structural planes of grade 鈪

本文编号：2295980