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Abstract 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.
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Received: 27 September 2010
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2011, Vol. 30 
