Analyzing the Shear Behaviors and Parameter Sensitivity of CIPP-SP Interface

The cured-in-place pipe (CIPP) lining repair technology has been widely used in the field of trenchless repair of water supply steel pipes, where the bonding performance of the interface is critical to the stability of the composite structure. In order to elucidate the interfacial failure mechanism between the CIPP liner pipe and water supply steel pipe (SP), this paper innovatively studies the interfacial shear characteristics and damage behavior of CIPP and steel plate composite structure. The shear strength of the CIPP-SP interface under different working conditions was investigated by 33 sets of interface straight shear tests. The global displacement field and strain field of the interface were analyzed. A multiparameter prediction equation for the interface peak shear force was proposed. Sensitivity analysis was performed on each factor. The results indicate that the CIPP-PS interface exhibited a four-stage brittle failure. Increasing the pressure holding time, interface area, shear rate, and interface roughness significantly increased the interfacial shear strength, but the normal pressure and CIPP thickness had less effect. The softening properties of the lining material at low temperatures and short curing times reduced the interfacial shear strength. The impact of interface area, shear rate, CIPP thickness, pressure holding time, roughness, normal pressure, curing time, and curing temperature on the interface shear strength decreased in order of their influence. The interfacial displacement field exhibited a centrally reduced stratification, and the strain field was the first to show strain concentration at the fixed end of the composite structure.