大型洞室群围岩破坏模式的动态识别与调控

FAILURE MODE DYNAMIC RECOGNITION AND CONTROL FOR SURROUNDING ROCK OF LARGE-SCALE CAVERN GROUP

在归纳地下工程围岩破坏模式分类、分析方法和控制措施等方面研究成果的基础上,建立大型地下洞室群围岩破坏模式的分类方法。该分类方法充分考虑大型洞室群大尺寸、大高宽比和多洞室相互作用等特点,依据控制因素、破坏机制、发生条件3个层次归纳出18种典型的围岩破坏模式,给出每种破坏模式的主要稳定性分析方法和针对性控制措施等方面的建议。并进一步根据大型洞室群分步开挖过程中不断更新的工程地质条件和围岩性状,提出围岩破坏模式的动态识别、复核与调控方法。该方法已成功应用于锦屏二级水电站地下厂房洞室群的开挖过程中围岩破坏模式识别和实时工程措施(开挖和支护)调控,实现施工过程中围岩局部不稳定性问题的识别、预测与动态调控。实践表明,该方法实用、科学和系统,可有效地指导大型地下洞室群施工过程中的开挖与支护设计动态优化,避免局部不稳定性问题的发生。

On the basis of system analysis and summary of the existing research results of failure mode classification, analysis methods and controlling measures of surrounding rock for underground engineering, a new failure mode classification method for surrounding rock of large-scale underground cavern group is proposed. The special features such as large span, high sidewall and cross of multi-cavern influencing on failure modes have been concerned in the method. Based on the three levels： control factors, failure mechanism, generation conditions, 18 typical failure modes have been summarised. The corresponding stability analysis methods and control measures are recommended for each failure modes. Furthermore, a new method is also proposed for dynamic recognition of failure modes and the corresponding control measures according to dynamic updating of geological conditions and characters of surrounding rock revealed during excavation. The new methods have been applied to dynamic construction of Jinping II hydropower station. The potential failure modes and corresponding stability analysis methods as well as control measures on excavation and support design are recommended before the construction of powerhouse. During the excavation layer by layer, the failure modes, excavation and support strategies are calibrated, recognized and modified according to the revealed actual geological conditions and characters of surrounding rocks. The procedure is continued until complete of the construction. The practice indicates that the methods are applicable, scientific and systematic, so as to provide an effective way for excavation and support design optimization during construction and avoid occurrence of local instability problems.