Results of a Full-Scale Fault-Offset Test on a Glass Fiber Reinforced Polymer Pipe

Glass fiber reinforced polymer (GFRP) pipe is increasingly being used as a corrosion resistant alternative to steel for distribution pipelines. Since these may be subject to flexural stress caused by ground movement, this study examines the response of GFRP pipe to permanent ground deformation and the failure mechanisms exhibited. A 6 m GFRP pipe segment was buried in dense olivine sand in a moveable split box able to simulate a 90° normal fault line. The segment was buried 1.2 m deep and subjected to fault offset of 120 mm. Point data was gathered at locations of maximum curvature using strain gauges to corroborate continuous fiber optical strain data taken lengthwise along the crown and invert. Fiber data corroborated strain gauge data where they coincided although fibers were ineffective after exceeding 8000 micro strain. Strain data initially showed little sign of material failure in the pipe, but upon further analysis fiber data showed that as fault offset increased, the strain increase between reading intervals increased at the maximum tension point. Immediately after excavation the segment showed little sign of physical damage aside from some residual deformation. Then weeks after excavation the segment recovered its original shape and cracking had become visible around the point of peak curvature.