The stability and lives extension of marine pipes are important in coastal engineering and the factors that influence the pipelines are corresponding to the coastal environment. To stabilize the pipes, blocks are a good solution and they are widely utilized in the engineering field. In this study, marine pipes are sited 0.5 meters higher than the sea bed and attached with blocks. With 1 m/s currents and sea bed which size of sand is 0.2 mm, we calculate the force load on marine pipes to analyze the relation among currents, change of sea bed and the structure including a marine pipe with blocks. A three-dimensional computational fluid dynamics code, FLOW-3D, solves Navier-Stokes type equations embedded with turbulence closure models is used. RNG model is utilized to solve turbulence calculation. Velocity, force load, and turbulent characteristics which are inconvenient to measure in the field are simulated and investigated and the drag coefficients under various situations are computed. Moreover, the interactions among current, sediment flushing and marine pipes with blocks are also discussed. The influences on the marine pipes caused by the distance between blocks are concluded and regressed for appropriate design. With proper prediction of impact on marine pipes and sediment flushing at sea bed, the stability and lives extension of sea pipes are expected to be improved in the future.
Pipelines are commonly used in the marine engineering, like taking cooling water from the sea to cool down the facilities and then discharging the effluent back to the environment. Since the pipelines play such an important role, they have become one of the significant concerns in application of engineering field, like Zhao et al. (2016) study the influences of pore pressure accumulations around the buried pipeline in the seabed and protected in trench layer with partial back fills. Chiew et al. (1990) and Sumer et al. (2002) also studied the souring situation around the pipeline. Tom et al. (2018) concluded that sediment transportation is related to the ratio of oscillation amplitude to cylinder diameter which is less than 12.
