Axial Compressive Behaviour and Calculation Method of Bolted Longitudinal Seams in Large-Wave Corrugated Steel Utility Tunnels

Large-wave corrugated steel utility tunnels have been widely used in underground engineering in recent years due to their excellent deformation adaptability and short construction period. However, research on the longitudinal joint bearing capacity is still insufficient and lacks an accurate calculation method for design guidance. In this study, axial compression tests were carried out on four groups of three-wave corrugated steel-plate high-strength bolted connection specimens with different plate thicknesses and bolt strength grades. Combined with finite element models extended to staggered seams, the effects of plate thickness and waveform on failure modes, bearing capacity, and force transmission characteristics were analysed. The test results indicated that the ductility of shear failure connections was obviously lower than that of bearing failure connections, and the brittleness of the shear failure mode became more pronounced as the difference between bolt shear strength and steel plate bearing strength increased. Numerical analysis revealed that although the bearing capacity of the seam improved with increasing waveform, the bearing capacity per unit width decreased. The ultimate displacement was related to the difference in strengths of the bolt and the corrugated steel plate, and the ultimate displacement in shear failure was much smaller than that in seams of bearing failure. The steel plate yielded progressively from both sides inwards along the corrugation direction. The bolt shear force distribution perpendicular to the loading direction exhibited considerable nonuniformity, with bolts at the staggered positions of the longitudinal seams being the first to fail. Based on comparisons of Chinese and American codes, and incorporating waveform and nonuniform shear effects, this study proposed bearing capacity equations for such connections. These equations accurately predict failure modes, with calculated results at 75–85% of theoretical values—a significant accuracy improvement over existing codes.