Etude de la nocivité du phénomène de coup de bélier dans les conduites enterrées

Abstract

In this thesis, numerical study, the three-dimensional finite-element method is used to analyze the degree of harmfulness of the water hammer phenomenon in high-density polyethylene (HDPE) pipes damaged by cracking. The fracture criterion used in this study is the integral J, which was calculated in semi-elliptical cracks in four different positions. The effect of the flow rate and crack configuration on the J-integral is analyses. The pipe section was constructed simulating a commercially available model. A 3D finite-element analysis was performed in Warp Software. All materials used in the models were considered to be isotropic, homogeneous, and linearly elastic. The results obtained show that an increase in pressure caused by the water hammer phenomenon leads to a remarkable increase in the J-integral. It is also shown that an internal longitudinal crack in a pipe is the most dangerous. One can also observe that an increase in the flow velocity, the pipe diameter, and the Young's modulus of the material lead to a considerable increase in the J-integral.