STUDY OF DEFORMATION AND FAILURE CHARACTERISTICS FOR SURROUNDING ROCKS OF UNDERGROUND POWERHOUSE CAVERNS UNDER HIGH GEOSTRESS CONDITION AND COUNTERMEASURES
(1. HydroChina Chengdu Engineering Corporation,Chengdu,Sichuan 610072,China;2. Key Laboratory of Geotechnical
Mechanics and Engineering of Ministry of Water Resources,Yangtze River Scientific Research Institute,
Wuhan,Hubei 430010,China)
Abstract:Underground powerhouse caverns of Guandi Hydropower Station have the characteristics of high geostress and widely distributed discontinuities in hard surrounding rocks. Based on the characteristics analysis of geostress,rock mass structure and the conclusions derived from the monitored deformation data and the three-dimensional numerical simulation results,the deformation and failure characteristics of rock mass are summarized. The countermeasures for general layout design,excavation support design,construction of powerhouse caverns under high geostress condition are proposed based on systematical summarization. Following proposals are made for high geostress condition,such as the direction of the maximum principal geostress and the main discontinuities in the surrounding rock should be taken into account when the longitudinal axis of the chamber is chosen;adopting larger distance between the main chambers;adopting larger ratio of height to span of the top arch;adopting reasonable methods and sequence for excavation;improving the strength grade of shotcrete;delaying concreting the rock wall crane beam and the lining of busbar tunnels;determining reasonable initial prestress of the anchor cables. Also,for surrounding rock where rockburst is likely to take place,it is suggested that the initial steel fiber shotcrete with a thickness of 50 to 60 mm should be sprayed firstly;and then to install the systematical anchor bolts;finally to implement the designed remaining shotcrete with wire mesh. The above-mentioned proposals provide great guiding significances and application values for design and construction of similar underground powerhouse caverns under high geostress condition.
张 勇1,肖平西1,丁秀丽2,欧文兵1,卢 波2,廖成刚1,董志宏2. 高地应力条件下地下厂房洞室群围岩的变形破坏特征及对策研究[J]. 岩石力学与工程学报, 2012, 31(2): 228-244.
ZHANG Yong1,XIAO Pingxi1,DING Xiuli2,OU Wenbing1,LU Bo2,LIAO Chenggang1,DONG Zhihong2. STUDY OF DEFORMATION AND FAILURE CHARACTERISTICS FOR SURROUNDING ROCKS OF UNDERGROUND POWERHOUSE CAVERNS UNDER HIGH GEOSTRESS CONDITION AND COUNTERMEASURES. , 2012, 31(2): 228-244.
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