Propagation characteristics of elastic wave in layered medium and applications of impact imaging method |
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Authors: | LIU Chao CHE Ai-lan FENG Shao-kong |
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Institution: | School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiaotong University, Shanghai 200240, China |
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Abstract: | It is an important subject to probe the structure in the medium by various kinds of detection methods in the geotechnical engineering. Based on the propagation theory of elastic wave in half-space layered medium, the propagation characteristics of elastic wave in layered medium with different elastic parameters are discussed using dynamic analysis of finite element method. It is known that the S-wave velocity, density and thickness of layer are related to the properties of the elastic wave including waveform characteristics, spectral characteristics and time-frequency characteristics. We pay special attention to the structure with low velocity interlayer. The impact imaging method is applied to the grouting construction of the immersed tube tunnel. Data acquisition and analytical method are introduced in detail. The grouting effects can be qualitatively evaluated by comparing the characteristics of elastic wave before grouting with those after grouting. Finally, a quantitative evaluation is obtained according to the relationship between energy response of elastic wave and impedance ratio. |
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Keywords: | layered medium elastic wave propagation characteristics impact imaging method |
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