Evaluation Of Landslide Impact On Submarine Pipelines Based On Strain Theory

With the developing demand of offshore oil and gas resource,the construction of the submarine pipeline will be longer and longer,and will inevitably traverse the slippery area.If designed based on stress,this would make the design too conservative,and the construction cost of the submarine pipeline would increase greatly.According to the latest research and practice,even if the stress of the submarine pipeline exceeds the yield stress under the effect of the landslide,the pipe will not be damaged as it has not reached the limit strain.Submarine pipeline design based on strain theory,however,at present,there are many problems in academia and engineering,especially the strain characteristics of submarine pipeline under the effect of landslide need be accurately grasped in the engineering field.In this paper,the elastic analysis of submarine pipeline under the effect of landslide is studied,and the relation between axial force and maximum displacement is analyzed.Then the elastic-plastic analysis of submarine pipeline under the effect of landslide is studied,and the numerical solution to the elastic-plastic equation is obtained.Finally the influence of different parameters on the strain of submarine pipeline under the effect of landslide is studied.In the elastic study of submarine pipeline,the theoretical derivation verifies that the axial force of the pipeline is approximately unchanged.In the study of elastoplasticity,the relationship between the plastic bending moment and the curvature is derived.Due to complexity of the elastoplastic equation,it is difficult to obtain the analytic solution directly,so the numerical calculation is carried out by the second order central difference numerical method.As the axial force of the pipeline is unbalanced,the axial force correction model is proposed,and it is applied to the axial strain derivation of the pipeline.Then according to changes of different parameters affecting the numerical analysis such as landslides,width,the horizontal resistance of soil,axial friction of soil,and so on,the elastic-plastic strain of the pipeline is in a certain regular changes.In this paper,the elastic-plastic theory deduction,axial force of correction and elastic-plastic research for submarine pipeline strain provide new ideas and perspectives,and provide important reference for pipelines design based on strain.