Experimental Study On Chloride Corrosion Of Prestressed Anchor Rod With Grouting Defects

At present,prestressed anchoring technology is widely used in the field of engineering construction.The intrusion of various corrosive media in its service environment can easily cause local corrosion of the rods.The cracks and grouting defects of the outer mortar inclusions of the anchor rods in the anchoring structure are The main cause that causes corrosive media to come into contact with anchor bars.In actual engineering,due to the uneven on-site construction,maintenance and management levels,the quality defects of the anchoring structure are very serious,and the corrosion safety problems caused by this are increasingly prominent.Therefore,the corrosion problem of prestressed anchor rods with grouting defects is necessary to carry out research.Using a combination of indoor immersion accelerated corrosion test and numerical simulation,this thesis conducts a systematic study on the corrosion durability of prestressed anchor rods with grouting defects.The corrosion development process of prestressed bolts with defects is studied by electrochemical testing methods;the local corrosion characteristics of bolt defects are studied based on metallographic scanning,SEM scanning and strain monitoring;the chloride ion transmission process is simulated and analyzed by numerical simulation software,and the influence of the depth and diameter of grouting defects on the mass transfer process was analyzed.The main research contents are as follows:(1)Through orthogonal experiment design,select 2 factors and 3 levels of grouting defect variables,and carry out multiple sets of prestressed anchor bar immersion corrosion tests,that is,set up mortar defects with different apertures and different hole depths,and measure the natural corrosion potential and polarity of the immersed anchor solids.Electrochemical parameters such as chemical resistance,corrosion current,etc.,based on electrochemical test parameters,to study the corrosion behavior and influence law of defect diameter and hole depth on the corrosion development of rods;based on the damage theory,the corrosion degree and service state of the pre-stressed anchor are evaluated.(2)Based on the corrosion appearance characteristics of the anchor bar after corrosion,the influence of the size of the defect on the prestress loss and corrosion products of the anchor bar is studied;through the analysis of the metallographic scanning,SEM electron microscope scanning and strain monitoring data of the defect position of the anchor bar after corrosion,the local corrosion characteristics of the defective locations of pre-stressed anchor bars are studied.(3)Based on the chemical rare substance transfer module of the COMSOL software,the simulation analysis of the equivalent chloride ion diffusion corrosion process of the prestressed anchor with grouting defects is carried out,the general rule of influence of defect hole depth and diameter on chloride ion transfer process is studied and verified with the test results.