P-wave attenuation in creeping rock and system identification

Summary The aim of this paper is to contribute to the evaluation of rock cracking using ultrasonic wave propagation. The rock specimens (siltstone sampled from a coal mine at a depth of 820 meters in Belgium) are subjected to incremental creep. The study of the rock transfer function shows P-wave attenuation in the direction of loading as a function of stress and time during the test: this attenuation becomes more significant at the stage at which the rock dilates. It is obvious from the specimen dimensions that the signal is affected by reflection phenomena. So, we have modelled the output sigrals with a model containing reflections. The simulations obtained from the model and input signal are very conclusive and the model validation is satisfying.