Session: 10-06-01 Pipelines and Cables

Paper Number: 127001

127001 - Numerical Investigation of the Vertical Settlement of Seabed Pipelines Under Horizontal Cyclic Loading in Clay 

As exploration moves into deeper water, offshore pipelines, generally laid on the seabed, are an increasingly significant component of offshore hydrocarbon developments. Seabed pipelines are mainly subjected to the wave loading, which causes vertical settlement of pipelines. In this study, the vertical settlement of seabed pipelines under horizontal cyclic loading in normally consolidated clay is investigated through the large deformation finite element (LDFE) analysis with the Coupled Eulerian Lagrangian (CEL) technique. The effects of strain rate dependency of the undrained shear strength and soil remoulding are considered by adopting an extended Tresca clay model during horizontal cyclic loadings. Firstly, the LDFE results are compared with centrifuge test results and published LDFE data, showing a good agreement. Then, a series of LDFE cases are conducted to investigate the effects of pipe weight, horizontal load amplitude, soil sensitivity, and trench depth on the accumulated vertical settlement of pipelines under cyclic loading. The LDFE results show that the affected clay zone around the pipeline due to cyclic loading is highly remoulded, and trench depth has an great effect on the accumulated vertical settlement of pipelines. With the increasing number of load cycles, the accumulated vertical settlement of pipelines is first increases and then decreases.

Presenting Author: Qi Wang South China University of Technology

Presenting Author Biography: Qi Wang received her Ph.D in December 2022 from South China University of Technology, Guangzhou, China. Her research focuses on soil-foundation interactions and site investigation tools for geotechnical engineering design by using experimental and numerical investigations. She has published several high quality papers on Computers and Geotechnics, International Journal of Geomechnics and Applied Ocean Research. She also servers as a reviewer for Ocean engineering journal.

Authors:

Xu Jia CNOOC Research Institute
Yi Liu CNOOC Research Institute
Lusheng Jia CNOOC Research Institute
Li Cheng South China University of Technology
Qi Wang South China University of Technology
Zhichao Shen South China University of Technology