Experimental study of propagation and attenuation of elastic wave in deep rock mass with joints

Laboratory modeling tests were performed to study the elastic wave propagation and attenuation in deep-buried rock mass with joints and the velocity and amplitude variation of elastic wave in jointed rock mass under different in-situ stresses were obtained. The propagation and attenuation of elastic wave in jointed rock mass were analyzed to study the relationships of the velocity increment and attenuation of elastic waves, the confining pressure, the number and angles of joints. The results of a triaxial compression test with constant confining pressure and increasing axial compression pressure showed that the change of elastic wave velocity had four phases: rapid growth, slow growth, stable state and rapid reduction. When the axial stress reached 60% of its strength, the velocity reduced rapidly, which indicated that the rock started to expand. The attenuation of the first wave amplitudes showed the similar trend of variation. In a triaxial tension-compression test with constant confining pressure and increasing axial tension pressure, the elastic wave velocity reduced gradually while the attenuation of amplitude grew. The results showed that the confining pressure, the angles and number of joints were all influential to the velocity and the attenuation of elastic wave. The degrees of influence sensitivity were in the decreasing order as: the number of joints>confining pressure>angles of joints. © 2015, Science Press. All right reserved.