Mechanical properties and damage mechanism of corrugated steel plate-concrete composite structures as primary supports of tunnels

To solve the problems of long construction periods, insufficient support strength, and pollution, which are associated with the traditional primary support of tunnels, the applicability of a corrugated steel plate-concrete (CSPC) composite structure as the primary support of tunnels is systematically investigated in this study. The structural stiffness, bearing capacity, and failure mode of the CSPC components were analysed using full-scale tests under combined compression and bending and numerical model. Furthermore, a numerical model based on a tunnel project supported by CSPC was established. The engineering project and numerical simulation were comprehensively analysed to verify the feasibility of the support scheme and validity of the numerical model. The effects of various geological conditions and structural design parameters on the mechanical performance of the structure were determined via a parametric analysis. The results indicate that axial force increases the structural stiffness of the composite structure in the plastic stage and reduces the ductility in the failure stage. An increase in the thickness and waveform of the corrugated steel plate (CSP) and concrete thickness considerably improves the mechanical properties of CSPC supporting structures, with the CSP waveform having the most prominent effect. When the cross-sectional height of the structure is fixed, large corrugated CSPs and low- strength concrete with a small thickness are preferred. Increasing the elastic resistance coefficient of the weak stratum to 70 MPa can enhance the mechanical properties of the supporting structure. Thus, the results of this study provide a reference for the design of CSPC composite structures as primary supports for tunnels.