Methodological Research On Ultrasonic CT And Rayleigh Waye Exploration As Well As Their Application

With the development of social economy, higher demands arc made on quality assessment in varieties of high standard new buildings and structures. In addition, in order to make maintenances and reinforcements of structures with supporting of evidences, it is also required to evaluate the present conditions of original structures. For ultrasonic CT and Rayleigh wave exploration have advantages of high efficiency, low cost and easy practice, they are applied broadly in engineering. But, the methods have their shortcomings. They cannot be well fit to the objects with small scale and the medium fast changing in space, and they will also be embarrassed by the testing of objects required higher resolution. To overcome these shortcomings, exploration methods for ultrasonic CT and Rayleigh wave and their applications in engineering are researched in this paper.This paper includes six sections. The first one expounds the research history of computerized tomography (CT) and Rayleigh wave exploration, and points out some currently existing problems. The second section and the third section detail with the theory of ultrasonic CT and Rayleigh wave, present solutions for some problems to improve the applicability of ultrasonic CT and Rayleigh wave exploration, and compile the computer program for ultrasonic CT, and improve the analytical program for Rayleigh wave exploration. In section four, the paper introduces the ultrasonic CT test and the Rayleigh wave test for detecting the weathering degrees of a white marble fence plate in Forbidden City and carries out some researches on the accuracy of the tests. A new approach to assess the weathering degrees of rocks by the variation of Rayleigh wave velocities is put forward in this paper, and the weathering degrees of the marble plate revealed by this method is exactly coincided with the actual weathering situation of this plate. In section five, in accordance with the drill prospecting, the paper applies the developed Rayleigh wave method to detecting the ground of the navy scientific experiment building, the result is also very well. All of these prove the applicability of Rayleigh waves method in engineering field and the feasibility of ultrasonic CT method to detect the weathering degrees of stone relics.In the sixth part of this paper, some problems left in the two methods are discussed, which make these methods still unsatisfied in some aspects.