METHOD AND DEVICE FOR INVESTIGATING PROPERTIES OF ROCK TO ESTABLISH THE PRESENCE OF LOOSE BLOCKS ADJACENT TO THE SURFACE THEREOF

摘要

When scaling rock, in particular in connection with blasting rock chambers and rock tunnels, the presence of loose blocks adjacent the surface of the rock is detected by bringing at least two electro-accoustic transducers into contact of the wall of the rock under examination at a distance from each other and comparing phase or amplitude or, as the case may be, both these properties of voltages generated by the electro-accoustic transducers in dependence of mechanical oscillations present in the rock. The presence of a block which is separated from the adjacent mass of rock is detected by evaluating amplitude or phase, or both, of signals generated by the or to each two, respectively, transducers when brought into contact with the rock surface under investigation. When the transducers are in contact with a loose block, the ratio of or difference between signals generated by the two transducers differ from those obtained when the same transducers are brought into contact with the surface of solid rock, thus making observation or indication of the presence of a loose block possible.