Study On Interlayer Interaction And Static Stability Of Recycled Composite Pipe Repaired By Thin-wall Lining

Thin-wall lining repair technology is to use a special construction technology to combine the lining and the wall with corrosion defects to form a composite pipe.It can restore or improve the safety performance of the original pipeline to realize the regeneration of defective or abandoned pipelines.The inner lining of the repaired pipe and the outer pipe wall form a composite pipe.The interlayer interaction and interlayer delamination stability between the thin-wall lining and the outer pipe wall are studied and analyzed,which provides a theoretical basis for the stability analysis of the recycled composite pipe repaired by the thin-wall lining.A bilinear cohesive force finite element analysis model was established based on the interlayer interaction obtained from tangential and normal tensile tests of composite pipe and compared with the experimental data.Based on the bilinear cohesion model,a three-dimensional shell model of the thin-walled FRP lined repairing recycled composite pipe and a finite element analysis model of the thin-walled stainless steel lining repairing the recycled composite pipe were established.The influence of radial force on the interaction between the lower layers and the peeling state of the lining of the composite pipe under different repair modes and different working conditions was studied.The results show that the critical peeling load of the thin-walled FRP lining does not increase with its thickness.The effect of outer base pipe wall thickness on the critical peeling load of thin-wall lining is small,while the diameter thickness ratio of outer base pipe has a greater effect.The three-dimensional finite element analysis model of the composite pipe was established to study the interlayer interaction state and the overall stability of the composite pipe when the external pipe wall with different corrosion degree was repaired by different repairing methods and different lining thickness under static operation.Under the action of axial force,the critical buckling load of outer wall of composite pipe and the ultimate load of complete failure of composite pipe under each working condition are obtained,and the influencing factors of changing these two critical loads are analyzed.Under the condition that the corrosion degree of the outer pipe wall and the thickness of the thin-walled inner lining are the same,the critical buckling load of the regenerated composite pipe repaired by the thin-walled stainless steel lining is greater than that of the thin-walled FRP lined repaired recycled composite pipe.However,due to the good interlayer interaction between the thin-walled FRP lining and the outer tube wall,the thin-walled FRP lining is not easy to peel off.For the composite pipe with less corrosion on the outer pipe wall and thinner inner lining,the ultimate load of the composite pipe repaired by FRP is greater than that of the composite pipe repaired by stainless steel.Under the action of bending moment,when the corrosion degree of outer pipe wall and the thickness of thin-wall lining layer are the same,the extreme values of bending moment that can be borne by the repaired pipe with thin-wall FRP lining are greater than that of the repaired pipe with thin-wall stainless steel lining.With the increase of corrosion pit depth,the difference of ultimate bending moment between them increases further.Due to the effect of interlayer bonding,the repair effect of thin-wall FRP lining is better.In this paper,a finite element analysis model for the repair of recycled composite pipes with thin-walled linings is established,and the interlayer interactions of recycled composite pipes and their stability under static force are studied and analyzed.The analysis model can well simulate the stress state of the composite pipe under different loads,which can lay a foundation for the research and technical application of the regeneration of the composite pipe with thin-wall lining.