Analysis of Repeated-Load Field Testing of Buried Plastic Pipes

Abstract

This paper describes a full-scale field trial carried out on plastic pipes buried in trenches, which were repeatedly loaded by a heavy vehicle driven along an overlying haul road. The vertical deformation of the pipes was recorded throughout the test for up to 1,000 loading passes and was observed to increase rapidly during the initial loading cycles with the rate of deformation reducing markedly as further cycles of loading were applied. This indicated that the pipe/soil system became more stable by repeated stress application. Power-law curves were developed from the recorded field data and were used to predict the long-term pipe deformation from initial loading cycles. The curves showed good correlation, and the predicted values agreed closely with measured values. The two types of surround material (nominally compacted sand and gravel) were found to have little effect on the rate of accumulation of deformation.