Buckling behaviour of internal stiffened thin-walled stainless steel liners under external constraints

As a trenchless repair technology for water-supply pipe networks, the thin-walled stainless-steel lining method has been widely used in China in recent years. However, because of the nature of the pressure pipeline, the inner lining often bears the negative pressure of the system, resulting in its instability. Through full-scale testing, numerical simulation, and theoretical analysis, the mechanical properties and buckling and post-buckling behaviours of the lining under stiffening were studied, and the influence of various parameters on the critical buckling pressure of the lining system was analysed. The results indicated that structural stiffening can effectively improve the buckling instability resistance of the system. With an increase in the stiffness of the stiffening part, the lining demonstrated a change from global to local buckling. Through comparative tests, the reinforcement coefficients of the host pipe were obtained, and a design model was established to predict the critical buckling instability of the inner lining, which was consistent with the actual FEM results.