Effects of grouting voids on the elastic buckling of confined pipe liners subjected to uniform pressure

Abstract

This paper focuses on the buckling of thin-walled confined liner with grouting voids, subjected to uniform external pressure. Based on the analytical and numerical results for three different void lengths, the single lobe deformation of the liner is observed for small void length; the double lobes deformation occurs for the medium void length, and single lobe deformation is found for large void length. Small grouting voids show negligible effects on the confined liner, and the critical buckling pressure can be predicted analytically by Glock's model. The analytical expressions of buckling pressure for medium and large voids are developed analytically and numerically in the present work. Analytical solutions are based on the principle of minimum potential energy and admissible displacement functions. In the numerical analysis, a two-dimensional (2D) finite element model (FEM) is developed by tracing the pressure-displacement equilibrium paths to obtain the critical buckling pressure. Both the analytical and numerical results show the medium and large grouting voids significantly reduce the buckling pressure. The numerical equilibrium paths and critical buckling pressures excellently agree with their corresponding analytical solutions.