Research On Nondestructive Testing Technology Of Grouting Members Based On Acoustic Energy Characteristics

The grouting member is a kind of members widely used in bridges and buildings.Its structural integrity can be improved by pouring the grouting materials into the member.Two typical grouting members include grout sleeve members and concrete-filled steel tube members.Generally,the grouting members play a key role in the structure,and the grouting quality has a direct impact on the structural integrity and is critical to meet the safety,durability and applicability of the structure.Because the concealment and complexity of slurry-injecting process for the grouting members lead to possible void,honeycomb and other defects occurring after completion of slurry injection,quality evaluation of grouting members is a necessary step to ensure its safety and applicability.Acoustic method is a widely used nondestructive testing method.Based on the acoustic energy characteristics,this paper researches the nondestructive testing technology of grouting components.With the acoustic analysis method,comparative analysis is conducted to the time domain,frequency domain,energy and other signal characteristics of acoustic signals and the characteristic parameters that reflect the internal state of grouting members are extracted through the energy characteristics of signals,which facilitates to improve the detection accuracy of grouting quality and is of significance to the evaluation of internal grouting quality of grouting members.The following sections describe the main research contents and results herein:(1)The influence of grouting defects on acoustic propagation characteristics of grouting sleeve members was researched.The control group of grout sleeves that include those with and without voids were created with the finite element software COMSOL Multiphysics,and the acoustic characteristics of the received signal,including time domain,frequency spectrum and energy,were analyzed to observe the influence of the sleeves with and without voids on the time-domain plot.Extract the characteristic parameter and define it as local resonance scattering attenuation characteristic parameterαto evaluate the grouting quality of grout sleeve.Set the grout sleeve models with different grouting amounts to analyze the parameters.The results show that the local resonance scattering attenuation characteristic parameterαcan be used to determine whether there is any void in the sleeve and its value increases with the decrease of grouting amount.(2)The influence of grouting defects on acoustic propagation characteristics of concrete-filled steel tubular members was researched.The control group of concrete-filled steel tubes that include those with and without defects were created with the finite element software COMSOL Multiphysics,and the acoustic characteristics of the echo signal,including time domain,frequency spectrum and energy,were analyzed to observe the influence of the steel tubes with and without voids on the acoustic signal.Extract the characteristic parameter and define it as the introduced energy characteristic parameter E_Uto evaluate the grouting quality of concrete-filled steel tube,and analyze the energy characteristic parameter through the simulation with honeycomb defect.The results show that the energy characteristic parameter E_Uis used to identify the grouting defects in the concrete-filled steel tubes.(3)The specimen models of grout sleeve and concrete-filled steel tubes were made respectively and have undergone the acoustic wave test.The test results of the grout sleeve model show that the local resonance scattering attenuation characteristic parameters can effectively describe whether there are voids in the tested surface.The test results of concrete-filled steel tube show that the energy characteristic parameters can effectively describe whether there are voids on the tested surface and can facilitate to identify the grouting state in concrete-filled steel tube structure.In this paper,the characteristic parameters of the test signal were extracted based on the energy characteristics,which can reflect the grouting quality of the test component,and provide a theoretical basis for rapid detection and quantitative detection.