Research On Method Of Detecting Grouting Quality In Prestressed Double-row Duct Based On Elasticwave Technique

With the prestressed concrete bridge is widely used in the construction of bridges,prestressed bridge disease is also increasingly prominent.The quality of the prestressed bridge ducts grouting has been concerned by scholars.The defects of the grouting will lead to prestressed steel strand corrosion and bridge prestress losses,which will directly affect safety,stability and durability of the bridge.So far,relative researchers detect the defects of prestressed duct based on single-point detection with only a duct in the path.With the using of double-row duct,the detection and location of grouting defects in double-row duct is the basis of the life and safety of bridge.In this regard,on the basis of summarizing the existing detection methods and signal processing status of prestressed duct grouting,the basic equations,propagation rules,detection technology principles and methods of elastic wave are introduced in detail,the signal processing technique applied to the elastic wave detection of the prestressed duct defect is studied.The influences of the material of the duct,depth of the duct placement,shape of the cross section,and size of the excitation hammer in the experimental results were analyzed by constructing a simplified prestressed double-row duct beam as the same size of the actual bridge.According to the data,the relationship between the frequency and elastic wave reflection position in the experimental beam was established.The correspondence relationship between the defect position and spectrum of the prestressed double-row duct was established.The shortcomings of impact echo method applied to the defect detection of prestressed double-row duct are proposed and the solutions are provided.Finally,through the analysis of the experimental results,the grouting quality judgment standards of prestressed double-row duct is established,and the feasibility of prestressed double-row duct grouting quality by elastic wave detection is verified.The elastic wave method used to test the grouting quality of prestressed double-row duct provides the basis for accurately judging grouting quality,and position of defects,the reference and guidance for the supervision and control of prestressed bridge quality.