Experimental Study On Corrosion Damage Of HDPE System Of Stayed Cables Under Environment And Loading

High Density Polyethylene(HDPE)sheath material is widely used for cable protection of stayed cable bridges due to its excellent mechanicals and environmental resistance indicators,and has gradually become a modern stayed cable bridges main form of protection of the cable.A large number of engineering practices have shown that due to the existence of many uncertain factors in the selection of raw materials,production,transportation,installation,operation,and maintenance management of cable HDPE sheaths,it is easy to cause physical,chemical,and mechanical properties of HDPE sheath materials.The change of the HDPE causes it lose its original excellent performance and even failure.The service life of the HDPE sheath is directly related to the actual service life of the cable structure and even the entire bridge.At present,most domestic and foreign scholars’ researches on HDPE sheaths have stayed in the single simulated service environment stage in the laboratory,and the actual service life of HDPE sheaths is quite different from that of HDPE sheaths.Multi-factor research is also lacking.Therefore,the systematic study of the environment and the load acting on the corrosion and aging behavior of the HDPE protection system of the cable and revealing its damage mechanism can not only provide a certain reference for accurately assessing the remaining life of the cable body and timely replacing the cable,but also extend the cable The actual service life of HDPE protection system,improving the design of cable HDPE protection system and avoiding major engineering safety accidents have important theoretical significance and engineering application value.This article relies on the National Natural Science Foundation of China “Research on the Mechanism and Life Prediction Model of Corrosion Fatigue Damage of Stay Cables under the Coupling of Alternating Loads and Erosive Environments”(No.51478071)and the National Natural Science Foundation of China’s Major Scientific Instrument Development Project “Structures under Complex Environment Development of Fatigue Experiment System(No.11627802)",starting from the durability study of cable structure of stayed cable bridge in service environment,guided by common diseases affecting HDPE protection system of service cable,surrounding cable structure and HDPE Corrosion damage and degradation of mechanical properties of the system,analysis of its disease and its causes,through theoretical analysis,experimental simulation,finite element modeling analysis,numerical analysis,etc.A number of factors were used for in-depth research.The corrosion damage process and damage mechanism of the cable HDPE protection system and cable structure system were systematically studied.The main research work and results are as follows:Firstly,research on the durability and damage mechanism of cable HDPE protection system: Based on extensive investigation of relevant domestic and foreign literature,and combined with the study of the main types of diseases of cable HDPE protection system in actual engineering,the durability of cable HDPE protection system was proposed.Related factors and damage mechanism of HDPE protection system.Secondly,experimental study on corrosion damage and mechanical properties of HDPE sheaths of cable under environmental and load effects: Accelerated corrosion damage and mechanical properties test of HDPE sheaths of cable under environment and load effects,revealed under different environmental and stress conditions The mechanism of corrosion damage and the degree of corrosion aging damage(mass damage,apparent morphology,and micro morphology)of the HDPE sheath of the cable were studied;the mechanical performance degradation of the cable HDPE protection system after corrosion aging was studied by tensile tests,and it revealed that The degradation process of tensile mechanical properties(yield strength,elastic modulus,elongation at break)of the cable HDPE protection system during corrosion aging damage after corrosion damage and the functional relationship between the corrosion factors.Thirdly,experimental research on the corrosion damage of the cable structure system with different damage modes of HDPE sheath: Through the corrosive damage test of the cable structure with alternate action of wet heat environment and copper salt solution infiltration,the structure of the cable before and after the corrosion of the cable HDPE sheath under different damage modes is analyzed The changes in the macro and micro appearance of the system and the distribution of its corrosion characteristics;the anatomical analysis of the corroded cables,the analysis of the corrosion of the steel wires at different positions in the cable body of the cable system,and the relationship between the degree of corrosion and the environmental medium were established The corroded wire was cleaned,and the distribution of pits of the steel wire HDPE sheath under different damage modes was analyzed.Fourthly,Finite element numerical simulation of the cable HDPE protection system: By using ABAQUS finite element analysis software,the finite element modeling and analysis of the stress conditions of the HDPE jacket under different damage modes were performed,and the holes and longitudinal cracks of the cable HDPE jacket were revealed.3.The stress distribution of ring-cracked defects under different size widths and different defect depths,and the change law of the maximum equivalent stress.Fifthly,based on a comprehensive analysis and research on the cable HDPE protection system and the cable overall structure system,some related measures to ensure the safety and durability of the cable HDPE protection system are proposed.