Calculation and study of the stability of oblique under-crossing tunnels

The new constructing tunnel passing through the existing operating tunnel usually causes a certain settlement of the tunnel during the operation period. According to the typical working conditions of new tunnel oblique under-crossing the existing operating tunnel, relying on the north station of Qingdao subway line 8 oblique under-crossing line 3 project, a calculation model was established through MIDAS GTS NX and ANSYS software, respectively. The maximum settlement value and the corresponding position of the overlying tunnel after the excavation of the left and right tunnels of the new line 8 during the construction stage are studied, and the bending moment and axial force at different positions of the lining structure in using stage are studied, respectively. The results show that the existing tunnel has a certain settlement when excavating the tunnel close to an existing tunnel. But the settlement amount is less. During continuous construction, the settlement, bending moment, and axial force at different positions can meet the deformation requirements under normal construction measures. It provides a reference for the safe construction and lining design of the new tunnel oblique under-crossing the existing operating tunnel.