Lateral soil resistance to an untrenched pipeline under the action of ocean currents

A plane-strain finite element model is proposed to investigate the pipe-soil interaction mechanisms for the partially embedded pipe with two kinds of constraint conditions, i.e. freely-laid pipe and anti-rolling pipe. The numerical model is verified with updated mechanical-actuator experiments. The magnitude of lateralsoil- resistance coefficient for the examined anti-rolling pipes is much lager than that for the freely-laid pipes, indicating the end-constraint condition affects significantly the lateral stability of the untrenched pipeline in ocean currents. Parametric study indicates that the variation of lateral-soil-resistance coefficient with the dimensionless submerged weight of pipe is affected greatly by the internal friction angle of soil, pipe-soil friction coefficient, etc.