Performance verification of novel low-friction cured-in-place pipe for earthquake-induced ground deformation

A cured-in-place pipe (CIPP) rehabilitation involves the installation of flexible polymeric liners within existing pipes. In contrast to pipe replacement, CIPP offers a cost-effective and environmentally sustainable solution for pipe rehabilitation. In conventional CIPP rehabilitation, lining pipes are glued to existing pipes. Even if the joint that connects existing pipes breaks owing to earthquake-induced ground deformation, the lining pipe can still resist tensile deformation. Therefore, the CIPP rehabilitation pipe is considered as effective in preventing joint pull-out. However, because the lining pipe must resist the tensile force on its own after the joint breaks, the lining pipe undergoes large strain. With this background, a novel low-friction CIPP rehabilitation approach was developed in this study. A friction-reducing layer was inserted between the existing pipes and lining pipes to reduce the strain transmitted from the existing pipe to the lining pipe. The objective of this study was to investigate the seismic performance of the low-friction rehabilitation pipe compared with the conventional glued-type rehabilitation pipe under earthquake-induced ground deformation using finite element analysis. To this end, a bending test and numerical analysis were first conducted, and the numerical model was validated by comparing the experimental results to the analysis results. Subsequently, the seismic performance was investigated using a 100-m-long rehabilitation pipe model under earthquake-induced ground deformation. The novel low-friction rehabilitation pipe drastically reduced the strain acting on the lining pipe, indicating that the lining pipe is less likely to be damaged by earthquakes.