Study on the dynamic embedment variation of shallow embedded submarine pipelines in sand

Abstract

The clarification of the pipe–soil interaction mechanism is a critical link in the design of the in-situ stability of shallow embedded pipes in subsea areas, and the in-situ embedment of pipelines is an important parameter in the pipe-soil interaction mechanism. A large-scale plane strain model test was performed for a shallow embedded pipeline with horizontal cyclic motion in sand. Additionally, a numerical analysis model that is applicable to multicycle submarine pipe–soil interactions in sand was constructed, which can consider the dynamic change in the pore ratio of sand during the motion of a shallow buried pipeline. The development law of dynamic embedment and factors influencing the pipeline after multiple horizontal cycles were studied. A method for calculating the dynamic embedment of pipelines in sandy soil was proposed. The results reveal that horizontal cyclic movement of the pipe in sandy soil increases the embedment depth, and dynamic embedment rises by 1.09–11.78 times depending on the initial state of the pipeline. Furthermore, a soil berm rises on both sides of the pipe following cycling, and the sand around the pipe is sheared and shrunken, causing a large increase in soil resistance during the horizontal movement of the shallow embedded pipe.