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Abstract According to different joint collecting areas，the revealed rock joints are collected and described finely during construction of central drift of Jinjishan multi-arch tunnel with eight traffic lanes based on the probabilistic method. Then the key block theory is adopted to predict the possible unstable blocks during construction progress of the main tunnel. In the meanwhile，the geometric and mechanical parameters of the key blocks are defined to analyze the influences of construction procedure on the unstable blocks. Furthermore，by comparing and analyzing the safety factor of the key blocks in different construction procedures，the design optimization analysis is performed. The results show that：(1) During the construction procedure of the main tunnel of Jinjishan multi-arch tunnel，the blocks located in the side surrounding rock mass are stable. (2) The key blocks with considerable volume in the top surrounding rock mass may be formed. (3) The numbers and the volumes of the key blocks may decrease in the construction procedure with excavating the right side drift first of the double-side drift method. The research results provide guidance for safety construction of Jinjishan multi-arch tunnel with eight traffic lanes.
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Received: 20 January 2010
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2011, Vol. 30 
