Mechanical response of the main tunnel before and after breakthrough at the receiving end of the cross passage

Abstract In order to investigate the response mechanism of the main tunnel breach at the receiving end during the construction process of the pipe jacking method in the liaison channel, relying on the liaison channel project of a shield tunnelling interval of Zhengzhou Metro Line 12, the deformation, internal force and stress-strain evolution of the main tunnel structure before and after the breach are analyzed by combining the on-site strain monitoring and three-dimensional finite element simulation. The results show that: 1) the stress concentration in the half-cut ring arch waist area after the main tunnel breakthrough, the peak value of Von Mises stress reaches 13.8MPa, and the maximum value of ring strain is 413 με, and the deviation between the simulation results and the field measured data is less than 5 %. 2) The main tunnel structure shows an asymmetric deformation tendency after the breakthrough, and the pre-supporting system effectively inhibits the structural deformation in the early stage, but the breakthrough triggers the unloading of the surrounding rock and the structural stiffness change, leading to the intensification of local convergence. 3) The main tunnel structure shows a trend of asymmetric deformation after the breakthrough. The tunnel breaking construction changes the internal force distribution mode and transfer mechanism, the axial force of the cutting ring is significantly reduced, and the neighboring structures share the load through the stiffness synergistically. The results of the study can provide a theoretical basis and technical reference for the construction of pipe jacking and receiving breaching in the cross passage.