Modeling of scour under submarine pipelines exposed to irregular wave attack

In the recent years, transport of oil, natural gas and various fluids are transported by submarine pipelines which are the practices of coastal engineering and one of the research topics. The triple interaction between submarine pipeline, bed and flow (wave, currents) causes scour around submarine pipelines. Scour under submarine pipelines plays an important role in terms of construction and operation of submarine pipelines. In this study, local scour depth around rigid different diameter submarine pipelines placed at different depths on horizontal and (1/10) sloping beaches exposed to normal-incidence irregular wave attack was experimentally investigated. Before the scour experiments were started, the shore-normal evolution of the beach profiles were examined, because the study area is in a shoaling region. All the parameters affective on local scour depth under irregular wave conditions and various non-dimensional parameters have been investigated separately. The results of the irregular wave tests were evaluated together with the results of tests with regular waves conducted by Çevik [104]. Here, the key issue is to choose the wave parameters to characterize the sea state of irregular wave attack which causes the same scour depth as that caused by regular wave attack. To predict the local scour depth considering both the data obtained in this study from irregular wave experiments and the regular wave experiment by Çevik [104] and using the deep water wave parameters and local wave parameters separately as input data, the alternative models with the method of ANNs were developed. So, in this study, models were proposed for solving the engineering applications.Keywords: Scour depth, irregular waves, pipelines, ANN