Segment Cracking and Damage Mechanism of Curved Shield Tunnels During Construction by Field Investigation and Modeling

Abstract

This study was based on the field statistical results of segment cracking and damage of a curved shield tunnel engineering. Combined with the collected data of 11 related tunneling parameters of 120 segments in the curve section, the one-way analysis of the variance method was used to reveal the main tunneling parameters that affect the cracking and damage state of the segment. Then, the finite element analysis model was established to analyze the mechanism of jack thrust and yawing angle affecting segment cracking and damage. The main results are as follows: (1) The phenomenon of segment cracking and damage gradually becomes serious from the crown to the invert. (2) The jack thrust and shield machine yawing angle are the main factors affecting the cracking and damage state of the segment. For larger values of yawing angle and jack thrust difference, the cracking and damage state of the segment is more serious. (3) The first three segments near the jack are significantly affected by the jack offset angle and uneven jack thrust. During the construction of a curved shield tunnel, under the action of the jack offset angle and uneven jack thrust, the segment spring line is more likely to incur tensile cracking. (4) To ensure the normal stress state of the segment during construction, it is suggested to control the jack offset angle at not more than 0.5° and the jack thrust non-uniform coefficient ${\psi }_{EF-BC}$ of the left- and right-hand sides within 0.75.