Analysis Of Local Buckling Collapse In J-lay

J-lay is a new deepwater laying technology based on S-lay.Under the combination of hydrostatic pressure,axial force and bending moment in the laying,pipeline most likely occur local buckling,once beyond the critical load of buckling failure,the collapse of pipeline will emerge and hamper laying operation.As the depth of water increasing,pipeline,especially located near touch down point,will take bigger risks of buckling collapse.This paper studies the critical load of buckling failure in J-lay.Firstly,the static analysis of pipeline is carried out on the method of catenary.Secondly,based on the criteria of DNV and loading control,the calculation formula of critical load is established.Thirdly,as the limitation of the catenary theory around TDP,applying segmented model and large deflection beam theory,an improved equation is listed and solved by the technology of singular perturbation.Finally,the results of the local buckling sensitivity analysis show the following conclusions,the hydrostatic pressure is the main factor which leading to local buckling collapse,then for J-lay,large diameter and thin thickness of the pipeline should be preferred,furthermore the risk of local buckling collapse could be reduced by adjusting the laying angle.