Numerical Assessment on the Mechanical Performance of Pressure Pipe CIPP Liner with Local Defects in the Outer Host Pipe

Abstract

Due to technical, economic and logistical factors, cured in place pressure pipe (CIPP) liner systems have become one of the preferred options to rehabilitate damaged, ageing water pipe. There is a need to better understand the mechanical performance and limit states of the CIPP liner across a range of practical design parameters. In this study, the three-dimensional continuum finite element analysis was conducted to assess the effects of local defects in the host pipe on the mechanical performance of the CIPP liner subject to internal pressure, axial deformation and flexure loading conditions. For a CIPP liner subject to internal pressure with local circular void defects in the host pipe, the limit state was governed by axial tension when the defect diameter to CIPP diameter (d/D) ratio was greater than 0.4. A yield response was observed for the higher liner diameter to wall thickness ratios (D/t > 60) and hoop stress to yield ratios (σh/σy ≥ 0.6). The effects of a circumferential gap defect on the CIPP liner mechanical response were evaluated. For internal pressure loading, the longitudinal distribution of normalized radial displacement for the CIPP liner was primarily influenced by the width of the circumferential gap defect width to CIPP liner diameter (g/D) and the CIPP D/t ratio. The CIPP liner mechanical performance with circumferential gap defects in the host pipe when subject to internal pressure and pipe rotation was also investigated. The defect gap ratio (g/D) had an impact on the CIPP liner deformation pattern. The host pipe/CIPP liner interface friction coefficient had a negligible effect due to the mobilization of a virtual anchor. iii Co-authorship This thesis contains material prepared in the manuscript format. The principal investigator was Xiaoan He where he was the primary responsible person to define the problem statement, establish the analysis matrix used in the parameter study, develop the numerical modelling procedures, conduct the numerical simulations, and report on the data synthesis, analysis and conclusions. Guidance, mentorship and editorial support was