Predicting the creep lives of thin-walled cylindrical polymeric pipe linings subject to external pressure

Installation of a close-fitting polymeric thin-walled lining is now standard practice for the rehabilitation of deteriorating gravity pipes. Design of these linings focuses primarily on their ability to resist an external head of groundwater pressure whilst experiencing long-term creep deformations. Existing structural design guidelines are crude and do not provide consistent safety factors. In this paper an existing simple analysis for linear elastic (geometrically non-linear) buckling loads is developed into a time stepping procedure for calculation of the creep lives of time dependent non-linearly elastic systems subject to long-term constant pressure. The results so obtained using different simulations of the creep data obtained for a particular material are then compared with those derived from a set of corresponding physical tests and alternative numerical modelling, and appropriate conclusions are drawn.