Pipeline Stability Under Finite-Amplitude Waves

The lateral stability of a bottom-laid pipeline under finite-amplitude waves which are shoaling on a mildly-sloping, rigid beach is considered. Incipient sliding motion conditions are assumed in which the wave-induced hydrodynamic pressure force is statically balanced by the Coulomb bottom friction force on a rigid, impermeable seabed. The Morison equation is employed to compute the wave-induced hydrodynamic pressure force. This static balance results in a dimensionless stability parameter that may be equated to a dimensionless wave force acting on the pipeline in order to determine lateral stability. A dimensionless wave force is computed using water particle kinematics computed numerically from the finite-amplitude Dean stream function wave theory. Design curves for predicting this dimensionless wave force acting on a pipeline under various design wave conditions are provided. Engineering applications are included which use the dimensionless wave forces to predict the maximum depth required to stabilize a bottom-laid pipeline on a rigid, impermeable beach under specified design wave conditions.