Stability Analysis and Protection Scheme of a Buried Subsea Pipeline with Soil Liquefaction and Seabed Scour

Abstract

This study performs stability analyses of a subsea pipeline buried in the seabed, taking into account soil liquefaction and seabed scour. Initially, the maximum liquefaction depth of the seabed under wave action was determined through theoretical analysis. For regions where the pipeline embedment depth is less than the maximum liquefaction depth induced by waves, a rock berm protective method is proposed to mitigate the potential for pipeline flotation in the liquefied soil. Furthermore, in light of the potential scour phenomenon, numerical models have been developed to predict both the general scour in the regional sea area and the local scour around the rock berm. Subsequently, the liquefaction depth induced by wave action on the scoured seabed surrounding the pipeline was analyzed. The effects of primary influential parameters, including wave height, wave period, compression modulus, shear modulus, and consolidation coefficient, among others, on the liquefaction depth were investigated. Finally, a protective method comprising a rock berm and concrete mattress for the pipeline is proposed to mitigate seabed liquefaction. This study offers a comprehensive procedure for the stability analysis and design of protective measures for subsea pipelines situated on liquefied and scoured seabeds.