Experimental evaluation of axial restraint and pretension on the response of fusible PVC pipes crossing a normal fault

Differential ground movements can impose significant stresses along buried pipes as well as cause ruptures or joint openings. The presence of axial restraints along pipes (e.g., thrust blocks or service connections) has the potential to increase stresses and influence the bending response of the pipe when subjected to ground movements. This study describes the results of three large-scale experiments that were conducted to investigate the influence of axial restraint and pretension on the bending response of a buried fusible polyvinyl chloride (FPVC) pipe crossing a normal fault. The pipe responses were monitored using distributed fibre optic sensing (DFOS), and the experimental data were compared to results from beam-on-spring analysis. The experimental results show that, for the FPVC pipe examined in this study, axial restraint and pretension had a negligible effect on the peak bending strain for normal fault offsets up to one pipe diameter. Experimental results were then used to evaluate a numerical model using beam-on-spring analysis. The modelling results show that an equivalent diameter steel pipe was more sensitive to axial restraint, especially at normal fault offsets greater than one pipe diameter, where axial restraint led to a 10 % reduction in peak bending strain when compared to the unrestrained case. • External control of actuators used to apply axial restraint and prestress to buried pipes during large-scale normal fault tests. • DFOS provides insight into axial restraint and pretension effects on axial and bending response of buried FPVC pipes. • Test results are compared with beam-on-spring analysis, which is also used to assess axial restraint effects for a steel pipe. • Axially stiffer (e.g., steel) pipes are more sensitive to axial restraint than flexible (e.g., FPVC) pipes.