Research On Rayleigh Wave Method And Its Application To Inspection For Weathering Degrees Of Lithoid Cultural Relics

With a history of more than 5000 years, China has numerous ancient architectures around thecountry. The most common type — stone structures, which always suffer deterioration fromhuman behavior and environmental weathering, require immediate evaluation and rehabilitation.However, the historic and aesthetic value of the lithoid relics restricts the preservationists to suchan inspecting method that it should cause little damage on the examined object. Moreover, thesize of the lithoid relics requires the method by a high precision in inspection. Thus it isfundamentally necessary for the engineering preservationists to find a non-destructive techniquewhich is efficient in application, accurate in inspection and less perturbative to the objects underevaluation.The invention of Spectral Analysis of Surface wave method(SASW) was inspired by geophysicalexploration and later introduced into engineering surveying. Based on the dispersioncharacteristics of Rayleigh wave in layered media, this technique obtains by analyzing behaviorof wave propagation from soil a dispersion curve, which could later be transferred into dynamicparameters to explain the geometric and material property of the investigated object. It is widelyused in civil engineering inspection due to the simplicity of testing arrangement and operation,and rapid acquisition of information about the soil. In this paper, the author managed to apply theSASW method in investigating small-size lithoid relics, and drew the velocity profile as anillumination of non-uniform weathering of them.The paper includes four sections: The prelude shows the research history and currentachievement of SASW theory and application. The second section, including the second andthird chapters, presents the basic forward theory and inverse method. Two computationalalgorithms are listed. Factors that affect the shape of dispersion curve are discussed. In the thirdchapter an inverse technique combined with unwrapping process and GA algorithm is alsoproposed. The third section mainly talks about the selection of testing facility and arrangement.The processing of in-situ data and result is listed in the fourth section. The dissertation ends witha conclusion of work already done, as well as suggestions for further research.