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Abstract Wucun tunnel is a two-way and six-lane tunnel with complex structure in Xiamen City，which is composed of double-arch tunnel，small-distance tunnel，initially supported multi-arch tunnel and split tunnel. Vault settlement and convergence of surrounding rock are the main in-situ monitoring work，and the monitoring results are comprehensively analyzed combined with the measures and procedures of tunnel excavation. Research results show that vault settlement in main tunnel is less than half of that in guide hole in three-hole method construction area；and it is shown that the double-arch structure is applicable to the tunnel with higher settlement control requirement. Vault settlement derived from CRD1 can exceed half of the total value settlement during the excavation period. If the measuring point is embedded after excavation of core soil，the lost settlement will be approximately 37.5% of the total. Surrounding rock can be reinforced by full-face curtain grouting，which achieves better control in vault settlement than in convergence of surrounding rock. Under the influence of dead weight and larger cross-section of pipe roof chamber，larger vault settlement appears in pipe roof area. The removal of temporary support has less impact on the displacement of surrounding rock. Construction factors such as excavation mainly lead to larger convergence deformation as well as grouting；the latter produces a greater impact. Excavation in right tunnel has a certain impact on secondary lining in left tunnel.
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Received: 04 September 2009
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