Shear behavior of cylindrical pin-sleeve connectors of neighboring segments of immersed tunnels

Abstract

A pin-sleeve system was used as a shear connector at the joints between the segments of the Dalian Bay immersed tunnel. To investigate the structural behavior of the pin-sleeve connectors, eight push tests were performed, and an analytical model was developed. Each specimen consisted of three reinforced concrete blocks representing the tunnel segments and two parallel joints between the three blocks connected by pin-sleeve connectors. The design of the specimens was aimed at studying the influences of the assembly error of the tunnel segments, corrosion of the shear pins, and group effect of the pin-sleeve connectors on their structural behavior. The specimens differed in the initial opening of the joints, diameter of the shear pins, and number and spacing of the connectors in one of the two parallel joints. The main conclusions drawn from the experimental investigations are as follows: (i) The joints mainly fail because of the failure of the shear pins. (ii) The effect of the initial joint opening on the ultimate bearing capacity was insignificant. (iii) A reduction in the cross-sectional area of the shear pins by 36% resulted in a reduction in their bearing capacity by 51%, indicating a non-proportional relationship between them. In addition, the derived formulae allow for a more reliable computation of the ultimate shear forces of the pin-sleeve connectors compared to those obtained from those taken from codes of practice. Finally, a simple formula was obtained using polynomial regression, which can be easily applied by engineers.