Research on Predicting and Distribution of Stratum Displacement of Double-tube Parallel Shield Tunnel

In order to discuss the distribution of stratum displacement of double-tube parallel shield tunnel due to the excavation,based on the stochastic medium theory and non-uniform convergence mode of tunnel section,a formula of stratum displacement for double-tube parallel shield tunnel is derived,and the proposed method is adopted to discuss the distribution of stratum displacement of double-tube tunnel under different location configurations and buried depths. Furthermore,the validity of the proposed method is verified through practical engineering. It is found that( 1) the stratum inner displacement above tunnel is vertical settlement mainly,and the values,influence ranges and distributions of stratum displacement are different in different stratum depths above the tunnel;(2) compared with the stratum displacement in shallow depth,the stratum displacement in deeper depth is larger,while its influence range of stratum deformation is smaller and the characteristics of double-peakof stratum settlement trough is more obvious;(3) for the configuration of the double-tube tunnel with inclined alignment, the horizontal displacement of soil mass distributed asymmetrically;(4) there is a horizontal shear deformation of soil mass in different directions,and an additional shear force would be applied to the underground structure within this zone during the tunnels' excavation.