(1. School of Civil and Hydraulic Engineering，Hefei University of Technology，Hefei，Anhui 230009，China；2. State Key Laboratory of Coal Resources and Mine Safety，China University of Mining and Technology，Xuzhou，Jiangsu 221000，China；3. Anhui Key Laboratory of Civil Engineering and Materials，Hefei University of Technology，Hefei，Anhui 230009，China)
Abstract：The metro line 1 in Hefei is in a close distance to piles of a viaduct foundation. Shield tunneling of the metro line 1 could therefore affect the safety of the piles of the viaduct. The stresses and the horizontal deformation of the piles and the ground settlements under different working conditions during the process of shield advancing were analyzed based on the mechanical principle of coupled springs for bridge-pile structures and the finite difference method. Close-distance shield tunneling with the nearest distance of only 0.63 m was found to have great effect on viaduct piles and the magnitude of the effect was closely related to the position of shield machine. The effects were superimposed upon the shield advancing of the twin tunnels in succession. As the shield was gradually close to the piles，the bending moments，the shear forces and the displacements were increased continuously. The maximum superimposed values of the bending moments，the shear forces and the horizontal displacements were 700.5 kN•m，159.6 kN and 2.39 mm respectively and were occurred when the head of the shield just passed the second row of piles and the shield tail just entered the first row of piles in the right tunnel. The space formed at the peripheral of lining segments in the rear of shield tail was found to be the main cause of the ground loss when jack pushed forward the shield machine. The flexural equation of piles was fitted by the displacements from the monitoring of piles. The bending moments and shear forces of piles in various advancing steps were thus calculated and the calculation method was verified by a case study.
2014, Vol. 33 
