白鹤滩水电站柱状节理玄武岩力学特性及松弛控制  

Mechanical characteristics and relax control of columnar jointed basalt at Baihetan hydropower station

作　　者：张春生 徐建荣 吉华 刘宁 倪绍虎 ZHANG Chunsheng;XU Jianrong;JI Hua;LIU Ning;NI Shaohu(PowerChina Huadong Engineering Corporation Limited,Hangzhou,Zhejiang 311122,China)

机构地区：[1]中国电建集团华东勘测设计研究院有限公司,浙江杭州311122

出　　处：《岩石力学与工程学报》2022年第7期1297-1309,共13页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(U1865203)。

摘　　要：柱状节理玄武岩是由火山熔岩冷凝收缩形成的典型节理岩体,岩体结构呈“柱状镶嵌构造”,具有非连续、非均质和各向异性等复杂力学性质,岩体的卸荷松弛控制是白鹤滩水电站工程建设的关键难题。结合近些年的研究成果,首先追溯柱状节理玄武岩的地质成因及演化,介绍白鹤滩柱状节理玄武岩的工程岩体分类。通过现场地质勘查、岩石力学试验和数值模拟分析,阐述柱状节理玄武岩的非连续性、各向异性与尺寸效应等力学性质。针对坝基和地下洞室的松弛变形问题,基于现场监测与数值分析揭示柱状节理玄武岩的松弛特征与时间效应。分析坝基与地下洞室在结构体型优化及开挖支护方法上的防松弛控制措施,总结柱状节理玄武岩松弛控制的支护时机和支护方法。研究表明,白鹤滩柱状节理玄武岩具有显著的卸荷松弛特性,对结构体形适当进行优化能减少松弛范围,在开挖前预先进行加固措施能提高岩体抗松弛能力,开挖后尽快采取支护措施改善应力状态有利于限制浅层岩体松弛向深部发展。Columnar jointed basalt is a typical jointed rock mass formed from the contraction of volcanic lava. The rock mass has “columnar mosaic structure” showing complex discontinuous,heterogeneous and anisotropic mechanical properties. The control of the unloading relaxation is thus a key problem to the construction of Baihetan hydropower station. Based on the research results in recent years,the geological origin and evolution of columnar jointed basalt are first described. The engineering classification of Baihetan columnar jointed basalt is then introduced. The discontinuity,the scale effect and the anisotropic mechanical property of the columnar jointed basalt are obtained through geological examinations,rock mechanics tests and numerical simulations. Based on the field monitoring and the numerical analysis on the relaxation deformation of the dam foundation and the underground cavern,the relaxation characteristics of the columnar jointed basalt are revealed. The anti-relaxation control measures of the dam foundation and the underground cavern in the optimization of structure shape and excavation support method are analyzed,and the supporting time and methods for relaxation control of the columnar jointed basalt are summarized. This study shows that the Baihetan columnar jointed basalt has significant unloading relaxation. Optimization of the structural shape can reduce the relaxation range. The anti-relaxation ability of rock mass can be improved by reinforcement measures before excavation. Support measures to alter the stress state immediately after excavation are effective to limit the spatial extension of relaxation.

关 键 词：岩石力学 柱状节理玄武岩 各向异性 卸荷松弛 工程措施 

分 类 号：TU45[建筑科学—岩土工程]