A New Long-term Corrosion Monitoring Method Of Steel Bar Based On Spiral Distributed Optical Fiber Sensor

Corrosion of steel bars was a key factor affecting the durability and reliability of reinforced concrete structures,and was the main cause of damage to concrete structures.Therefore,it was very necessary and important to study the long-term monitoring method of corrosion of steel bar.However,existing corrosion monitoring methods for steel bars have problems,such as monitoring range was small and long-term measurement cannot come to realize.Therefore,it was urgent to establish a new longterm monitoring method for steel corrosion.Distributed optical fiber sensing technology has attracted wide attention from academic and engineering circles at home and abroad because of its incomparable advantages such as small size,easy to combine with structure due to its softness,and corrosion resistance as well as distributed measurement.Based on the analysis and research of the existing fiber optic strain sensing technology,and taking the reinforced concrete structure as the research object,a new long-term monitoring method of reinforced steel corrosion based on spiral distributed optical fiber sensing is proposed,and the law of expansion failure of reinforced concrete structures due to the corrosion was studied.The main results are as follows:(1)The principle of reinforcement corrosion monitoring based on spiral distributed optical fiber sensing is put forward.The mathematical model of corrosion expansion and cracking of reinforced concrete was established,and the numerical analysis was carried out.The parameters affecting circumferential stress are analyzed.Meanwhile,the process of corrosion expansion was simulated.(2)A spiral distributed optical fiber sensor for monitoring corrosion of steel bars was successfully manufactured.Through elastic mechanics theory,the winding radius,pitch and spiral angle of the spiral distributed optical fiber sensor are theoretically analyzed.Finally,the structure design parameters and technology of the spiral distributed optical fiber sensor are established,and the spiral distributed fiber sensor was successfully developed and used to verify the corrosion test of the reinforcement structure wrapped in mortar.(3)A new method of long-term corrosion monitoring for steel bar was verified by model test.The failure law of corrosion expansion of reinforcing concrete was explored.The spiral distributed optical fiber sensor was implanted into the concrete structure.Through accelerated corrosion test,a model test platform for long-term monitoring of reinforcement corrosion of reinforced concrete structure was set up.The dependence of time on steel bar corrosion was obtained,and the law of corrosion and expansion damage of reinforcement in concrete structure was illustrated.