Experimental Study of Shock Wave Spread Rule Monitoring with FBG Sensing for Lithologic Characteristics

Abstract

Abstract To obtain the influence mechanism of lithologic characteristics when rock bust shock waves transmit through rock, the waves in different rock were monitored with fiber Bragg grating (FBG). The result shows that the wave will change the period Λ and effective refractive index n of FBG, and further affect the initial wavelength value. The amplitude, phase and frequency of shock wave are directly related to the wavelength drifts of FBG. The transmitting velocity of shock wave in rock is affected by lithologic characteristics. The Elastic modulus, density and Poisson’s ratio of rock influence the initial wavelength value of FBG in the form of I = 2 E ρ ( 1 + υ ) , and are Cosine related to wavelength drifts. The experiments of shock waves monitoring were carried out in sandstone, limestone and marble respectively. The result shows that the lithologic parameters of rock were Cosine related to the initial wavelength value of FBG. This study provided a theoretical basis and practical application guidance for coal or rock burst monitoring with FBG sensing.