Study On The Laws Of Surface Deformation Caused By Shield Construction And Control Technology Of Xi’an Subway Tunnel

Study on the laws of surface deformation caused by the tunnel shield construction andhow to control the nearby surface structures deformation has important theoreticalsignificance and important application value in the Xi’an loess area. Based on Xi’an subwayline one from Wu lu kou to Chao yang men, using theoretical analysis, numerical simulationand engineering practice to study. The major work and conclusions as follows:(1) Analyze the mechanism of the surface deformation caused by the tunnel shieldconstruction. Study the laws of surface deformation caused by construction methods,formation conditions, depth, and ground loss ratio. Discusses the surface deformation controlstandard and its determination methods, they can provides some corresponding theoreticalbasis for control the surface deformation during the tunnel shield construction.(2) Using the stochastic medium theory to study the surface deformation caused bybi-directional tunnel shield construction. Study the laws of surface deformation caused byvarious influential factors, including depth of tunnel, the axis distance between two tunnels,tunnel profile convergence value and strata mainly affect angle.(3) Using FLAC3D software to study the deformation of the moat arch bridge when theshield tunnel underneath pass it construction. Study the laws of surface and moat shore andmoat bottom and the arch bridge deformation caused by the two kinds of work conditionswhich reinforcement and no reinforcement the old moat arch bridge. The results showed thatonly pre-reinforcement the old moat arch bridge before the shield construction, thedeformation of old moat arch bridge can be controlled in the range of allowable.(4) Offer the special protection when the shield tunnel underneath pass the old moat archbridge construction and on-site monitoring, the results showed that the measured settlementcurves approximate to the prediction curve very much. Engineering practice shows that the pre-reinforcement is effective. This research result can provide a reference to Xi’an subwayunderneath passing others buildings construction.