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| Cause Analysis on Damage of Adjacent Metro Shield Tunnel Due to Deep Pit Excavation with Pile - anchor Retaining |
| LIU Ting - jin1，XIA Wen - yu2 |
| (1. South China University of Technology， Guangzliou，Guangdong 510640, China; 2. State Key Lab of Subtropical Building Science，South China University of Technology，Guangzliou，Guangdong 510640，China) |
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Abstract Research purposes ： Some serious damages such as segment breakage，segment cracks，leakage in joints， side ditch cracking in ballast have always been fund in the metro shield tunnel，which induced by excavation of adjacent deep foundation pit with pile - anchor retaining. It threatens metro operation and structural safety of tunnel. In this paper，by means of analyzing surrounding construction process，damage status and relative monitoring data in the actual engineering case，the causes of tunnel disease have been preliminarily investigated from excavation disturbance of adjacent foundation pit with pile - anchor retaining and the property of tunnel deformation respectively which can provide reference for similar projects. Research conclusions ：( 1 ) Soil loosing region will occur in the end of anchor owing to excavation disturbance of adjacent foundation pit with pile - anchor retaining，which could decrease the restriction ability of lateral soil and induce the deformation trend of transverse ellipse of the tunnel. Meanwhile，the increase of upper load is another reason of the trend. (2) The deformation property of transverse ellipse is the main reason of segment breakage，joints leakage in the waist of tunnel, segment longitudinal cracks in the vault of tunnel. (3) The calculation and analysis of tunnel structural safety condition show that adjacent layer of the tunnel is in the status of loose caused by the excavation of adjacent pit, the segment ring deforms according to transverse ellipse. It is preliminarily concluded that some of connecting bolt was in the state of yield. (4) The research results can be used for reference of similar engineering.
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Received: 13 September 2015
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2016, Vol. 33 
