Abstract: The haunch height and sidewall compression ratio are key factors influencing the mechanical performance of bolted-connected slab-assembly precast utility tunnels. To investigate their effects, a nonlinear finite element (FE) model of the lower edge node is developed using ABAQUS software. The model′s accuracy is validated through low-cycle repeated load tests conducted on lower edge nodes in prior research. Based on this, a nonlinear FE model of the entire tunnel structure is constructed, and a parametric analysis is performed. The main parameters include haunch heights of 0, 100, 200, and 250 mm, and sidewall axial compression ratios of 0, 0.05, and 0.1. The results indicate the following: (1) The overall structure primarily undergoes bending failure, with forward ultimate bearing capacities ranging from 210.5 to 306.8 kN and ductility coefficients from 3.57 to 4.01. (2) Compared to the case with zero haunch height, the ultimate bearing capacities increase by 16.6%, 27.5%, and 31.7% for haunch heights of 100, 200, and 250 mm, respectively, while the ductility coefficients decrease by 3.24%, 3.51%, and 9.46%. (3) Compared to the case with a sidewall axial compression ratio of zero, the ultimate bearing capacities increase by 5.4% and 14.3% for compression ratios of 0.05 and 0.1, respectively, with corresponding increases in ductility coefficients of 12.32% and 10.36%.

Key words: utility tunnel, precast slab-assembly, bolted connection, overall structure, finite element analysis, ultimate bearing capacity, displacement ductility