Study on influence mechanism of lithologic characteristics for rock burst shock wave grating monitoring
To obtain the influence mechanism of lithologic characteristics when rock bust shock waves transmit through rock,the shock waves in different rock supports were monitored with Fiber Bragg Gratings(FBG),and the coupling relationships between them were theoretically analyzed.Based on Housner's random shock model,the coupling mechanism between shock waves and FBG was theoreti-cally analyzed.The result showed that the shock wave can change the period A and effective refractive index neff of FBG,thereby affect-ing their initial wavelength.Parameters such as vibration amplitude,phase,and frequency were directly related to wavelength changes.The transmitting velocity of shock wave in rock was affected by lithologic characteristics parameters.The elastic modulus,density and Poisson's ratio of rock influence the initial wavelength value of FBG,and were cosine related to wavelength drifts.The experiments of shock waves sensing monitoring were carried out in sandstone,limestone and marble slabs,respectively.The result showed that the li-thologic parameters of rock were cosine related to the initial wavelength value of FBG,which was consistent with the result of theoretical analysis.This study provided a theoretical basis and practical application guidance for coal or rock burst monitoring with FBG sensing.
rock burstFBGshock wavelithological characteristicsgrating monitoring
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