Characteristics of acoustic wave velocity variation in the process of deformation and failure of loading coal

Résumé

For studying characteristics of acoustic wave velocity change during the deformation and fracture of loaded coal, using self-made acoustic parameter test system the characteristics of acoustic wave velocity change in deformation and fracture of loaded coal, the mechanism of stress influencing acoustic wave velocity change, the relation between stress and longitudinal wave velocity and the impossibility of longitudinal wave velocity forecasting coal structure is studied. The research results show that during the deformation and fracture of loaded coal the longitudinal wave and shear wave velocity increases firstly. When the coal is damaged the longitudinal wave velocity decreases and the shear wave disappears. The stress-strain change of coal is similar to the stress-wave velocity change highly. Based on coal structure the formula of stress and longitudinal wave velocity is established and the longitudinal wave velocity can be predicted well under different stress by the formula of stress and longitudinal wave velocity. The mechanism of stress influencing acoustic wave velocity change is coal structure change mainly.