Working Face Stability Analysis of a Quasi‐Rectangular Pipe‐Jacking Tunnel Considering the Carrying‐Soil Effect

ABSTRACT Compared with circular shield tunnels, quasi‐rectangular pipe‐jacking tunnels have the advantages of smaller construction disturbances and higher space utilization rates, which are widely applied in urban underground engineering. The carrying‐soil effect is a specific phenomenon during the construction of pipe‐jacking tunnels. To study the influence of carrying‐soil effect on the working face stability of a quasi‐rectangular pipe‐jacking tunnel, the collapse and blow‐out failure mechanisms of the working face are established on the basis of spatial discretization technique. By analysing the mechanical mechanism of the carrying‐soil effect, the upper bound solution of the critical chamber pressure of the working face that considers the carrying‐soil effect is obtained in this paper. Based on an actual project, the theoretical results are compared with the numerical results, proving the effectiveness of the proposed method. Furthermore, parametric analysis indicates that the jacking distance of the pipe‐jacking tunnel has a significant influence on the working face stability, while the influence of the frictional force between the soil and the pipe is relatively small.