Optimization study on longitudinal joints in quasi-rectangular shield tunnels

Featured Application: (1) The damage process of the newly adopted type of longitudinal joint with ductile iron joint panels (DIJPs) in quasi-rectangular tunnels was obtained. (2) The effect of bolt position improvements was investigated through joint tests. (3) Within the service conditions, the joint behavior could be divided into three stages under both positive and negative moments. (4) Effects of the modifications related to concrete and bolt properties were explored. (5) Through comparison, increasing the lever arm between bolts and the compression zone to resist exerted moments is believed to be the most effective optimization method. There are large bending moments in quasi-rectangular shield tunnels due to their deviation from the circular shape, and as for other types of shield tunnels, the longitudinal joints are the most critical parts in the lining structure. A new type of joint with ductile iron joint panels (DIJPs) was installed in quasi-rectangular tunnels to solve these problems. The distance from the bolts to the segment's inner surface was improved for better performance under specific bending moment types. Both tests and finite element modeling (FEM) simulations were conducted to investigate the effect of the bolt position improvements. The resistances to crack appearance increased by 33.6% and 18.0% for positive and negative moment cases, respectively. The resistances to crack penetration increased by 13.8% and 18.4% for positive and negative cases. From the FEM approach, it was found that the behavior of the joint under the design bending moment range can be divided into three stages, whereby the bolts are only active from the second stage on. The effects of other optimizing methods, such as enhancement of concrete properties and increase of bolt diameters and numbers, are explored. Through comparison, it is believed that optimizing the joint section to increase the lever arm between bolts and the compression zone can improve the joint behavior most effectively. This optimization direction is recommended when designing a shield tunnel joint with DIJPs.

Jaar van publicatie:2021

Toegankelijkheid:Open