Rock-pipeline impact force and pipeline response during deep-water rock dumping operation

Abstract

Accurate rock dumping by rock-fall pipes is an important measure to protect submarine pipeline. For exploring the complicated operation process, the rock-seawater-pipeline interaction is analyzed, especially the function of rock-pipeline impact force is obtained based on the energy principle during deep-water rock dumping process. A coupled DEM-CFD model, verified by a classic case of single spherical particle settling from air to water and local rock dumping experiment, is applied to simulate the rock dumping process, the results indicate rock impact point deviates from the axial center line of pipeline for a certain distance when rock contacts pipeline in single rock dumping. While the force on the submarine pipeline oscillation rises to the peak value and then gradually falls, keeps basically stable at last in multi-rock dumping process. Further, the sensitive parameters of the force on pipeline are investigated and the study shows that the force on the submarine pipeline increases with the increase of rock radius, rock dumping height and rock density as a whole in single or multi-rock dumping process. Finally, the submarine pipeline response, manifests that single rock falling maybe damage pipeline while multi-rock operations are safety relatively, acquired by coupling DEM-FEM with fluid.