Abstract: Herein, the effects of prestressed reinforcement design parameters, axial compression ratio, and post-cast concrete thickness on the overall mechanical performance of the structure of a concrete modular double-cabin utility tunnel are investigated. A finite element model of the single-cabin tunnel is developed using ABAQUS finite element software. Based on this model, a structural model of the concrete double-cabin utility tunnel is established, and a parametric finite element analysis is conducted. The key parameters include the average sectional precompression stress (0.1, 0.2, and 0.3 MPa), sidewall axial compression ratio (0, 0.05, and 0.10), midwall axial compression ratio(0, 0.1, and 0.2) prestressed tendon arrangement, and post-cast concrete thickness (20, 30, 40, and 50 mm). The main findings are as follows: (1) An increase in average sectional precompression stress significantly enhances the structural ductility. Compared with an average sectional precompression stress of 0.1 MPa, the ductility improves by approximately 8.3% and 13.3% at 0.2 MPa and 0.3 MPa, respectively. (2) Axial pressure influences the structural bearing capacity. When the axial compression ratio is 0.05 and 0.10, the overall bearing capacity increases by approximately 5.0% and 10.4%, respectively, relative to the structure without axial pressure. (3) Under constant average sectional precompression stress, increasing the prestressed tendons in the top slab improves structural ductility, whereas increasing the prestressed tendons in the bottom slab reduces it. (4) The thickness of post-cast concrete has a limited effect on structural performance, with an improvement of no more than 2%.

Key words: concrete utility tunnel, finite element analysis, modular structure, overall performance, static behavior, ultimate bearing capacity