ANALYSIS OF STRESS AND DEFORMATION OF TUNNEL DUE TO ADJACENT SHIELD TUNNELING WITH DIFFERENT SPACING

Due to the continuous development and utilization in urban underground space, the spacing between adjacent tunnels in new projects is becoming smaller and smaller in constriction of the surrounding buildings. In case of a shield immediate adjacent double-line tunnel construction in Beijing subway, a three-dimensional (3D) nonlinear numerical simulation model to simulate earth pressure balance (EPB) shield tunnelling was set up. The developing law of the stress and deformation of the adjacent existed tunnel in variable tunnel spaces are analyzed in detail. The results show that the segment lining deformation is in ellipse deformation trend under horizontal compression and vertical tension. The simulation results obviously demonstrate that the deformation growth rate of segment lining is less than the stress growth rate of segment lining. The results also describe the sensitivity of the stress of segment lining to the variation of tunnel space. In plastic zones connected around double-line tunnel, the plastic zone form is similar to the case of the single tunnel construction due to very narrow tunnel space. The 3D numerical model directly displays the interaction of immediate adjacent tunnels during construction, therefore, it can be served as references for project design and the construction of adjacent variable spacing shield tunnels in future.