Experimental Study of Structural Response of Lined-Corrugated HDPE Pipe Subjected to Normal Fault

AbstractBuried lined-corrugated high density polyethylene (HDPE) pipes have been applied to transport sewage for decades. During its service life, a pipe of this kind could suffer from differential ground motion as a result of various geohazards (e.g., differential settlement induced by tunneling, basement excavations, changes in water table). However, studies of this kind of behavior of thermoplastic sewers have largely been absent in the pipe research literature. A full-scale test was conducted to investigate the structural response of 600-mm diameter lined-corrugated HDPE pipe subjected to differential ground movements associated with a normal fault having dip angle of 90°. This normal fault was simulated in a facility called the Split Box, where half of the floor of the test pit rests on screw jacks that allow it to be lowered in a stepwise process. Strain gauges and optical fibers were used to measure strains in the longitudinal and circumferential directions on the inner or outer surfaces of the pipe. Vertical displacement and cross-section distortion of the pipe were monitored using digital images analyzed using particle image velocimetry (PIV). Test results show that pipe strains were distributed nonlinearly around the pipe cross sections, especially for those measured proximal to the fault. Maximum pipe diameter changes were also observed at pipe cross sections close to the fault. The test results were compared with two current calculation approaches (i.e., the three-beam method and the Kappa method) and it is found that these two methods both overestimated peak bending strains in the pipe relative to those observed in the test.