1. Jiangxi University of Science and Technology, School of Architectural and Surveying Engineering, Ganzhou 341000,China;
2. China University of Geosciences, School of Engineering and Technology, Beijing 100083,China
Abstract:The waveform change of stress wave propagation across the interfaces can be described using amplitude transmission and reflection coefficients and phase transmission and reflection coefficients. The calculation model for transmission and reflection coefficients, for stress wave propagation through stratified rock mass, is established on the basis of considering fully multiple interlayer and intrastratal transmission and reflection. This paper calculates the transmission coefficient and transmission waveform of stratified rock mass using the established model, which has a very good agreement with the previous research results. The analysis results show that the model is reasonable. The effects of interface stiffness and thickness of stratum and interface number on filter property of stratified rock mass are discussed. The study results indicate that interface stiffness and thickness of stratum are main influence factors on the filter property of elastic stratified rock mass. And the stratified rock mass has the multi-scale comb filtering properties. The amplitude transmission and reflection coefficients have two-scale periodic change with the increased ratio of the stratum thickness to wavelength. The large-scale period, for intrastratal multiple transmission and reflection of stress wave across stratified rock mass, is 0.5. There exist a band-pass and band-stop in a large-scale period. There have multiple small-scale periods in a band-pass for interlay multiple transmission and reflection. The stratified rock mass possessed the multiple band-pass filtering property. The upper limit frequency and lower limit frequency of band-pass increase simultaneously with the increased interface stiffness. The increasing amplitude of upper limit frequency is more than that of lower limit frequency. The width of band-pass decreases approximately in a negative exponential form with the increased frequency. The center frequency of band-pass is about the integral multiple of the first order inherent frequency of stratum when each stratum thickness is equal. But, the stratified rock mass has the band-pass property only in the resonance frequency of stratified rock mass when each stratum thickness is unequal.
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