Probabilistic analysis of the pipeline embedment in spatially variable clay

Abstract

Offshore pipelines are generally laid directly on the seabed without any additional stabilization measures. The pipeline embedment is an important factor that determines the resistance of soil in the axial and lateral movement of the pipeline during operation. Although natural soil properties show considerable spatial variability, the majority of existing studies on pipeline embedment are deterministic. This study shows a probabilistic analysis of the pipeline embedment in the randomness soil using three-dimensional large-deformation random finite-element calculations with the Monte Carlo framework. The results indicate that the randomness of soil strength not only affects the failure mechanisms during the pipeline penetration process but also alters the pipeline penetration resistance. The mean penetration resistance in the randomness soil is less than the deterministic value. Consequently, deterministic analysis may lead to a non-conservative solution without considering soil spatial variability. The required safety factor ($SF$) is 2.0 to ensure that the failure probability ($FP$) of the pipeline embedment is no >0.1 %. Finally, a methodology is proposed for determining the $SF$ corresponding to different levels of $FP$ considering soil spatial variability. This is likely beneficial for engineers to evaluate the $FP$ for the deterministic design of the pipeline embedment according to the $SF$.