Research On Detection Method Of Sleeve Grouting Defects Based On Impact Echo Method

At present,the joint of prefabricated buildings in China is mainly connected by grouting sleeve,and the density of grouting in the sleeve will directly affect the performance of the sleeve.Because the grouting material is between the sleeve wall and the reinforcement in the sleeve and the space is too narrow,the existing detection method of sleeve grouting is not ideal.The existing detection methods of sleeve grouting mainly include video recording,damage detection and embedding.Video recording can't ensure that the sleeve grouting is dense even if the grout outlet is smooth.Damage detection can't be used in large scale and will cause damage to the sleeve.The cost of embedding method is high and the success rate of embedding is low.Therefore,this paper proposes to use impact echo method to detect the sleeve Inspection of grouting conditions.This paper introduces the principle of the impact echo method.The impact echo is produced by striking the concrete surface with a small hammer.Aiming at the impact echo itself,the propagation of the impact echo,the basic equation of the stress wave,the reflection and transmission are studied.After the impact echo produced by knocking is received by the testing instrument,the acoustic signal is converted into electrical signal,and the signal processing method is studied according to the information There are two different detection methods for signal processing: time difference method and vibration method.Finally,the detection process of impact echo method is introduced,which provides theoretical basis for the detection experiment based on impact echo method.The causes and consequences of grouting defects and the methods to avoid them are put forward,which provides the basis for simulating the detection of disease types.It mainly includes top grouting defect,horizontal grouting defect,middle grouting defect,reinforcement eccentricity,reinforcement missing,the influence of grouting material fluidity with time,the influence of grouting material type and material shrinkage,etc.in addition,it introduces the influencing factors of impact echo method detection accuracy,which provides the basis for the design of experimental specimens.In order to ensure that in the process of sleeve grouting,under the impact of grouting material,the defect position is fixed,the time difference method is used to detect the sleeve grouting before the embedded concrete test piece.After the detection,the accuracy of the preset defect reaches 95% Meet the requirements of further test.In this paper,the detection test of the grouting situation of the sleeve embedded in the concrete is carried out.Two methods of impact echo method are used to detect the grouting sleeve embedded in the concrete.After the time difference method is used to detect,the detection accuracy is 80%,which can detect the grouting defects qualitatively andquantitatively,but can't detect the lack of reinforcement.The vibration method is used to detect,the detection accuracy is 95%,which can detect the lack of reinforcement Grouting defects and reinforcement defects,but the vibration method is more complex than the time difference method.In the actual detection,it is recommended to use the time difference method to detect first,then select the points in the problem area for the second detection by vibration method,and detect the critical points of the reinforcement anchoring in the sleeve by vibration method to ensure that the reinforcement in the sleeve is not missing.The two methods are used together to ensure the detection accuracy and improve the detection efficiency.Combined with the detection data in the actual project,the impact echo method is used to detect the grouting The defect of sleeve is more practical.This paper provides a reference for the later compilation of assembly building acceptance code.