Mechanical Behavior of Composite Shell Lining Structures Based on Cohesion Models

With the development of tunnel construction, the number of composite-lined tunnels with spray membrane waterproofing is gradually increasing. To clarify the mechanical properties of composite shell lining (CSL) structures, mechanical parameters of interlayer waterproofing membrane materials were determined by conducting uniaxial tensile, interlayer bond tensile, and interlayer bond shear tests on waterproofing membrane materials with different water-cement ratios. The cohesion model is used to simulate the bonding characteristics between waterproofing membranes and concrete to develop numerical simulation calculation models of CSL and double shell lining (DSL) structures. The results of indoor tests and numerical simulations confirmed the feasibility of using a cohesion model to characterize the interlayer shear mechanical properties of the waterproofing membrane. Relative to the DSL, the stresses of the primary support of CSL and key cross-sections of the secondary lining are more similar owing to the synergistic force between the primary support and secondary lining caused by the bonding characteristics of the waterproofing membrane, resulting in the formation of a type of composite load-bearing structure, which improves the utilization rate of the primary support and reduces the thickness of the secondary lining. Therefore, the CSL structure based on spray membrane waterproofing has broad application prospects.