Fracture behavior of pre-cracked polyethylene gas pipe under foundation settlement by extended finite element method

Polyethylene (PE) pipes are often used for transporting gas and water, which play an important role in lifeline engineering. Such pipes, especially with notches, scratches or cracks, can be subject to actions inflicted by nature or man-made factors. To ensure that the pipes can continue to operate, even after being subjected to foundation settlement, it is necessary to study the fracture behavior of the pipes. In this work, a model was developed based on extended finite element method (XFEM) to study the fracture behavior of pre-cracked PE pipe under foundation settlement. Key parameters' effects on ultimate bearing capacity, including initial crack sizes, internal pressures and transition section length, were determined. Tensile results demonstrate that the stress-strain relationship of the pre-cracked PE pipe specimen involves two-stage, i.e., the elastic stage and the failure stage. There was obvious crack propagation in the macro fracture profile when the tensile test was performed on pre-cracked PE specimens. Simulation results demonstrate that the initial crack depth exerts a more significant influence on the ultimate bearing capacity for the pipe than the initial crack length. The internal pressure will enhance the bending resistance of the pipe, which inhibits crack propagation. In addition, the length of the transition section exerts a significant influence on crack propagation.

Automated summary

The study focused on the fracture behavior of pre-cracked PE pipes under foundation settlement. It was found that the initial crack depth has a more significant influence on ultimate bearing capacity, internal pressure helps inhibit crack propagation, and the length of the transition section also plays a significant role in crack propagation.