Numerical Simulation of Mechanical Properties of the Segments for a Curved Shield Tunnel during Construction Stage: A Case Study

摘要

Owing to the requirements of shield machine posture adjusting and direction changing in curved tunnel, the hydraulic cylinders of the thrust system are diverged from the axes of the segments, which will make the segments in an unfavorable loading state. In this paper, combined with the construction characteristics of large diameter shield tunnel with small radius curve in the intercity rail transit engineering from Zhuhai urban to Zhuhai Airport and based on the practical engineering condition and tunneling parameter recordings, a 3-D space finite element model was set up for the shield tunnel during construction stage. Further, numerical simulations were carried out according to different working conditions, and the force and deformation of the segments were analyzed and given. Also, through parametric analysis, the influences of several factors, such as curve radius and magnitude, direction, and deviation of the jacks, on the force and deformation of the segments during shield construction stage, were studied. The results show that the lateral deformation of the segment in curved tunnel is significantly greater than that in straight line section; when the magnitude of the jack thrust is changed from small to large, the position of maximum lateral deformation (MLD) of the segment in curved tunnel is gradually transitioned from the inside to the outside of the curve; and as the magnitude of the jacks increases, MLD of the segment decreases but the minimum principal stress increases with the increase of jack pressure difference and obliquity.