The Analysis For Large Deformation In Abandonment And Recovery Operation Of Submarine Pipeline

The deformation of submarine pipeline in abandonment and recovery operation which involves contract problem actually belongs to geometric non-linear problem with large deformation.The contact problem contains the contact between submarine pipeline and seabed,and the contact between submarine pipeline and stinger.The finite element method is applied in this paper.The spatial beam model is used to simulate the submarine pipeline.The method of U.L is applied.The large deformation of submarine pipeline is calculated and analyzed,and the software which has independent intellectual property about abandonment and recovery operation of submarine pipeline is programmed.As dealing with the problem of the contact between submarine pipeline and seabed,the method of displacement constraint and reverse-force constraint is applied;as dealing with the problem of the contact between submarine pipeline and stinger,the method of unilateral displacement constraint and correctional reverse-force constraint is applied.In order to prevent bending failure of pipeline in abandonment and recovery operation of submarine pipeline,the whole course is divided to three stages:the first stage is to supply axial tensile force,the second stage is to rise up the pipeline,and the third stage is that the pipeline crawls along stinger.According to these three stages,the numerical example of whole abandonment and recovery operation is given.The stress,deformation and the matching relationship between the retreat distance of stinger and the tensile force during installation are also calculated in this paper.Finally,by means of changing the maximal original tensile force in horizontal direction,the horizontal distance between picked up point on the pipeline and tail of stinger and pipeline's gravity in the sea, their effect on the maximal bending moment in pipeline during the first and second stages is solved in this paper.