A simplified theoretical prediction of vertical bending behaviour of structural pipe repair systems

Abstract

Internal replacement pipe (IRP) system is an emerging trenchless pipeline repair technology. Vertical bending caused by surface loads from vehicular traffic is considered to be the worst condition for IRP systems, particularly for host pipes with circumferential discontinuities. However, available studies on the flexural behaviour of IRP systems installed host pipes with discontinuities are limited. Moreover, a simplified and robust analytical model that can reliably predict the behaviour of discontinuous host pipes repaired with IRP systems subject to bending is not available. Consequently, a simplified analytical model based on fibre model analysis (FMA) was developed to examine the load-deflection behaviour of IRP systems in host pipes with circumferential discontinuities. Finite element analysis (FEA) was also performed to simulate the bending behaviour of the IRP system and to validate the FMA results. FMA showed a good correlation between the linear and non-linear load-deflection behaviours of the IRP in a host pipe with different discontinuity widths. The findings of this study will give the research community and construction specialities a better knowledge of the bending behaviour of IRP systems installed in gas pipelines with discontinuities resulting from circumferential cracking to scenarios where longitudinal sections are effectively missing. The FMA analytical model, which was calibrated and validated with experimental, and FEA numerical results, will be a very reliable and simple tool for predicting the flexural behaviour of IRP systems for trenchless repair, in contrast to expensive and time-consuming laboratory experiments and extensive FEA.