Experimental research on scour depth of submarine pipelines under complex wave conditions

The equivalent scour depth of submarine pipelines is always the key point in this field. Almost all existing formulas about scour depth of submarine pipelines have been tested only in unidirectional wave conditions and few formulas are about the skewed pipelines. But in fact, wave comes out from all the directions. They joint forces on the pipeline. Based on field data of Qinhuang Island sea area, this paper studies on submarine pipelines scour in different wave directions, different orientation of pipelines and different wave factors. It can be shown in the test that under the complex wave conditions, the pressure difference increases with the angle increasing, and that will make the scour hole deeper. According to the research, the existing formulas about the relative scour depth are not suitable under the complex wave conditions. An experimental formula about scour depth under complex wave conditions has been worked out by using regression analysis.