Detecting Weakened Mine Pillars Using Seismo-acoustic Noise - Results of Physical Modelling

We present the results of physical modelling, carried out to estimate the ability of detecting weakened pillars in the mine workings using seismo-acoustic noise. The experiments show that acoustic noise generates the compressional standing waves within the pillar models. The averaging amplitude spectra of a large number of noise records made on the pillar wall allows us extracting these waves from a noise field. As expected, the frequencies and the amplitudes of standing waves change with the changing in the pillar material and, correspondingly, in its elastic properties. Since in real conditions the velocities in virgin and weakened rocks are different, the frequencies and the amplitudes of standing waves generated by a noise in the pillars can be used for monitoring their stability.