Abstract: In this study, considering the natural stratification of the stratum, an analytical solution for the longitudinal displacement of a shield tunnel associated with an overcrossing tunneling in layered soils is proposed. The proposed solution can accurately predict the heave of the existing shield tunnel due to the overcrossing tunneling. First, the interaction between the shield tunnel and surrounding soil is analyzed and the overall coupling equilibrium equation between them is established. Second, based on Mindlin′s solution, the uplift displacement of the underlying layered soils due to unloading pressure induced by the excavation of a new tunnel is obtained. Moreover, the longitudinal displacement of the shield tunnel is obtained by combining with the overall coupling equilibrium equation. Finally, the results obtained using the proposed method are compared with the measurement data from three overcrossing projects, and the related parameters are analyzed. The results indicate the following: (1) Previous prediction methods based on elastic foundation beams and the proposed method satisfactorily predict the tunnel heave in the case of minimal stratification of the ground beneath the existing tunnel. (2) The predicted results from the proposed method concur with the measurements in the case of remarkable stratification of the ground. (3) Increasing the tunnel diameter will increase the uplift displacement and widen the range of the tunnel heave. (4) Reducing the clearance between the new tunnel and the existing tunnel increases the tunnel heave. (5) When the existing tunnel is located on the upper soft and lower hard strata, its uplift range is smaller but its uplift magnitude is greater than that of the upper hard and lower soft strata.

Key words: newlybuilt tunnel, existing shield tunnel, overcrossing tunneling, tunnel heave, coupling analysis method