Study On Acoustical Reflecting Model Detecting Shallow Cave And Interface In Concrete

Acoustical reflecting method, as a non-destructive inspection, has been widely used in geotechnical engineering. But when applied to detecting shallow lacunas in concrete, such as interior interface and cave, it lacks foundation of qualitative judgement and quantitative analyzed precision. Because the diversification of lacunas in concrete and the property of acoustical reflecting method is not understood completely, ideal purpose is hardly achieved actually.In this paper, actual theory of detecting lacunas in concrete are searched by studying models and analyzing acoustical property of these representative lacuna interfaces. On the ground of analyzing reflecting wave time-distance curves of several representative interfaces, interfaces and caves in concrete are endued with self-excitated and self-received method, shared excitation method, fixed sensor space reflection method, penetrated direct wave CT method, shallow wave CT method. Then data are analyzed by mathematical physics methods of single channel and multicenter time-domain frequency domain mape analysis, CT chromatography, matlab transcendental equation, etc. A conclusion is Drawn that shallow caves and interfaces in concrete can be detected by acoustical reflecting method with special testing collocation and rational frequence. And relevant applicable qualifications are given at the same time.