Experimental Investigation on Dynamic Response of Submarine Pipeline Over Flat Beds in Waves

Model tests have been conducted on flexible submarine pipelines over flat beds in both regular and irregular waves and the second order effect induced by waves are concerned within the certain range of Keulegan-Carpenter numbers and Reynolds numbers. The tests were conducted in the wave flume with 55m in length, 4m in width and 2.5m in depth. The pipelines were made by flexible pipe with 60mm in diameter and placed at various distances from a flat bed. Gap to diameter ratio varies from 0.4 to 0.8 when the pipelines are not sagging. The wave period in the model tests is in the range from 0.8 to 2.0 and water depth is 0.4m. The Keulegan-Carpenter numbers are less than 8.0 and the Reynolds numbers are in the subcritical regime. Bending strain was measured by strain gauges bonded on the inner surface of the pipeline. The strain amplitudes and second order effect are analyzed and discussed against various Keulegan-Carpenter numbers and gaps between the pipeline and the flat bed.