Quantitative Assessment of Damage in Buried Polyethylene Pipe Subjected to Land Subsidence

Traditional investigation of polyethylene pipe (PE) subjected to external loads focused only on the study of mechanical behavior or the failure judgment, but could not predict the damage evolution process. In this paper, a quantitative assessment was conducted for the damage of PE pipe subjected to land subsidence. Specifically, a static damage model was proposed based on failure pressure. Then, a finite element model of the buried PE pipe was established to calculate the failure pressure of smooth or notched pipe. Finally, the damage of the buried PE pipes suffering from land subsidence was computed by the damage model. The results show that the failure pressure and damage curves of smooth PE pipe can be divided into increased, steady, and reducing stages. For notched PE pipe, the damage curve can be divided into initial, middle, and late stages when the notch depth coefficient A (notch depth/thickness) equals to 0.1. But when A surpasses 0.2, the damage curve loses its middle stage and rapid damage follows. The threshold of the late stage of damage can be regarded as the last warning value of the damage of PE pipe under land subsidence, which indicates the maintenance measures should be taken immediately. The defects on the pipe accelerated the speed of damage and the late stage of damage evolution.