Simulation Analysis Of Sleeve Grouting Detection Of Assembled Pier Based On Impact Echo Method

Prefabricated concrete bridge has become an important technology to promote the development of new industrialization.The quality of its piers is a key factor affecting the overall performance of the structure.Due to the large thickness of the bridge pier and the small volume of the grouting sleeve,the conventional ray detection method and ultrasonic detection method are used to detect the sleeve grouting fullness of the connection point of the fabricated concrete bridge pier.The accuracy cannot be guaranteed.In view of this problem,based on the theory of impact echo method to detect the grouting quality of prestressed pipelines,this paper studies its ability to detect the grouting fullness of sleeve joints of fabricated concrete bridge pier,and determines the impact echo method to detect fabricated concrete Detection effect of grouting fullness of bridge pier sleeve joints.The basic theory of elastic waves is introduced from the aspects of the excitation and propagation characteristics of elastic waves,explaining the principle of signal acquisition and signal spectrum analysis methods of shock echo detection,and the basic principles and methods of detecting sleeve grouting quality by shock echo method.Using ABAQUS / Explicit display dynamic analysis,simulated impact echo method to detect the grouting defects of sleeve joints of fabricated concrete bridge pier,the feasibility of impact echo method to detect the grouting defects of sleeves of fabricated concrete bridge pier,and the detection effect of different test thicknesses.The results show that: ABAQUS / Explicit simulated impact echo method is feasible to detect the grouting defects of the sleeve joints of fabricated concrete bridge pier;the impact echo method can accurately detect the defect-free model of the bridge pier thickness of 2m,1.5m,and 1m;Concrete bridge piers can accurately detect defects through the thickness frequency of the defects.For models with a thickness of 2m and 1.5m,the thickness frequency at the bottom of the plate is shifted to high frequencies.For models with a thickness of 1m,the thickness frequency at the bottom of the plate is close to the calculated value,indicating that elastic waves cannot propagate to the larger thickness due to the presence of defects.Concrete bottom.The length of grouting defects of different sleeves and the test results of each measuring point are studied in detail.Through the comparison model,the influence of the steel bars,the size of the sleeve,the thickness of the protective layer and the layout of the sleeve on the detection results are analyzed.The results show that: the impact echo method can accurately detect defects with a defect length of 20% or more;the thickness can not identify defects within 0-100 mm at the end of the defect,and the middle range of the defect can be accurately identified;the size of the reinforcement in the sleeve and the sleeve The arrangement of the cylinder has no significant effect on the detection results of the impact echo method.As the sleeve size decreases,the detection error increases.The impact echo method can detect the assembled concrete bridge pier sleeves with a protective layer thickness of 100 mm,75mm,and 50 mm.The detection result of grouting defects and the thickness of the protective layer is 35 mm,and the error is large.In summary,through the dynamic finite element simulation of ABAQUS / Explicit display,the detection effect of the grouting defect of the sleeve joints of prefabricated concrete bridge piers by the impact echo method is obtained.Theoretically,it provides theoretical support for the impact echo detection method,and provides impact support The wave method is used to detect the sleeve grouting defect to determine the applicable conditions and detection range,and provides a reference detection method for the detection and acceptance of fabricated concrete bridge piers.