Reliability Based Evaluation Method For Flexible Pipe On-Bottom Stability

Submarine pipeline is widely used in the exploitation and transportation of submarine oil and gas resources.As the working environment of the submarine oil pipeline is relatively poor,once the instability will not only affect the exploitation and production of resources,bring economic losses,but also cause the pollution of the marine environment,and even cause ecological disasters.Most of the existing pipeline design methods are for steel pipelines,while the research on non-metallic flexible pipelines is relatively small.Therefore,in this paper,based on the actual operation of the submarine flexible pipeline in the Gulf of Mexico,theoretical calculation,numerical simulation and finite element method are used to carry out relevant research on the in-situ stability of the submarine flexible pipeline,and it is concluded that the method is suitable for flexibility The calculation and verification method of pipeline in-situ stability and reliability analysis method.In view of the above work,the following research contents are carried out: based on the absolute stability check method introduced in the specification,the lateral stability and vertical stability of different pipe diameters are calculated,checked and compared,and the appropriate counterweight is selected for them;the settlement process of the pipeline is simulated,and the influence of the settlement of the pipeline on the lateral displacement of the pipeline is analyzed;the construction A suitable soil spring model of pipe soil interaction is established to analyze the factors affecting the pipeline displacement;the stability of long-distance pipeline under environmental conditions is checked based on the finite element method;the pipeline design method based on reliability is used to solve the change of the pipeline stability under the influence of uncertain parameters,determine the sensitive items affecting the pipeline lateral displacement and calculate them Probability of failure.The results show that the design method based on the code is more conservative than the finite element design method;the larger initial settlement is helpful to improve the in-situ stability of the pipeline;the most sensitive factors affecting the lateral displacement of the pipeline are the diameter of the pipeline,the coefficient of inertia force and the coefficient of lateral friction of the soil;the displacement failure of the pipeline is mainly concentrated in the range of a certain pipe diameter,so it is in this range The piping should be weighted.