Study on Force Characteristics and Safety of Segment Structure and Bolts with and without Cavity behind Lining with Multi-Field Coupling

In this study, a refined three-dimensional stratigraphic–structural model is established based on ABAQUS finite element software, and the basis for determining pneumatic and vibration loads is explained in detail. From this, the force characteristics of the segment and bolts with and without a cavity behind the lining under the action of multi-field coupling were analyzed, and the force law and corresponding safety of the segment structure and high-strength bolts were determined. The results show that the peak value of the maximum principal stress on the segment structure caused by the surrounding rock pressure was 92.7 times greater than the variation in the peak value of the maximum principal stress caused by additional loads (pneumatic and vibration loads). Despite this, the safety factor of the segment structure satisfied the code requirements. Compared to the situation with no cavity behind the lining, when the cavity behind the lining was small the stresses of the segment structure were large and concentrated, which increased the possibility of crack development in the segment structure. The nodal stresses and strains on the straight and bending bolts exhibited an approximately “W”-shaped distribution with a cavity behind the lining. In addition to the effect of the preload near the nut, the stress and strain at the central measurement point of the bolt rod at the joint face were larger owing to the coupling effect of multiple fields. The high-strength bolt remained in an elastic state and did not yield with damage.