Study on the Seismic Design of Polyethylene Pipe During An Earthquake

Abstract eng:
Evaluation of the seismic performance of a buried pipeline changes depending on whether the pipe slips against the surrounding soil. When slippage occurs, stress and strain concentrate on junctions and bends. Important factors as to whether slippage occurs are the critical shear stress of the soil (τ cr ) and the elasticity of the pipe materials. Since there were few reports of experiments regarding τ cr of polyethylene pipe (HPPE), we conducted experiments to investigate the performance of HPPE. Our results are as follows: (1) τ cr of HPPE (straight pipe) is approximately 10 kN/m2 under 60 cm of backfilling soil. Therefore, we adopted a τ cr of 10 kN/m2, which comes from the experiments with steel pipe, although there is a large difference in elasticity between HPPE and steel pipe. This means that the existing seismic design method for buried pipelines can be applied to HPPE. (2) τ cr of HPPE with accessories including an Electric Fusion(EF) coupler and branch saddle rise to 10.8 kN/m2–19.5 kN/m2 because these accessories become the resistance in the soil. (3) We found that even HPPE can slip by approximately 12 mm in solid ground, which is approximately 1/20 of the maximum slippage of steel pipe. It was considered that the slippage of HPPE has little influence on junctions and bends.

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