Dynamic Characteristics of Submarine Pipelines and Experimental Validation of a Bedding Condition Assessment Approach Based on Mode-Shape Curvatures

Abstract

Due to the adverse operational environment, submarine pipelines are susceptible to the development of free spans under pipes, which may endanger the integrity of entire pipeline systems and subsequently inflict huge economic losses and huge costs to restore ecological conditions. To maintain the integrity of pipeline systems, it is very important to develop an effective and reliable approach to identify and localise free-spanning damage at an early stage. In this study, the influence of different bedding conditions on modal parameters of submarine pipelines is first systematically investigated by considering the subsea operational environment. Then, the feasibility of curvatures of lower-frequency mode-shapes for localising free-spanning damage of pipelines is discussed, and damage indicators based on mode-shape curvatures are proposed. Numerical simulations are conducted on a 100 m long pipeline to illustrate how to localise free-spanning damage using the proposed damage indicators. The efficacy of the proposed damage indicators is validated by experimental tests.