Mechanical performance of corrugated steel utility tunnel–concrete joint chamber structures considering soil–structure interaction

Corrugated steel utility tunnels offer high bearing capacity, favorable prefabrication, and economic benefits, with broad application prospects. In practice, joint chambers are required at utility tunnel joints and are mostly built as reinforced concrete structures. Owing to the stiffness contrast between the corrugated steel tunnel and the concrete joint chamber, the mechanical performance of a corrugated steel utility tunnel–concrete joint chamber (CS-CC) structure differs markedly from that of a corrugated steel tunnel alone. To investigate this performance, a three-dimensional finite element model was established and gravity load analysis was conducted. Results show that the concrete joint chamber alters the soil stress transfer path and the boundary constraints of the corrugated steel tunnel. Parametric gravity analyses were performed using the horizontal and vertical relative deformation ratios, D k cspx and D k cspy , as evaluation indices. Increasing wall thickness reduces both indices, whereas burial depth and cross-sectional dimensions are positively correlated with them. Subsequently, dynamic time-history analyses were conducted using the GM7 record scaled to the rare earthquake level of intensity VIII under P-wave, SV-wave, and P + SV-wave inputs. The entire structure remains elastic under this earthquake level, but notable damage occurs at the shear key connections of the concrete joint chamber. The seismic input mode significantly affects the dynamic response, with P + SV waves producing the strongest effect. Finally, a simplified pushover method based on free-field soil time-history analysis and the response displacement method is proposed. For GM7, the maximum errors in D k cspx and D k cspy are 17.178% and 20.216%, demonstrating good applicability and predictive accuracy.