For deep level hard rock mines, tailored preconditioning techniques have been used to control face bursts for safer mining in seismically active and therefore hazardous areas. Preconditioning is tailored to the rock mass and mining conditions. GPR is a useful tool to determine if completed preconditioning had been effective at fracturing behind the face and de-stressing based on the blast parameters.
Mining mesh is used as an additional safety measure to contain the skin of the development face and often used in conjunction with preconditioning. Mesh covering the rock face could distort a GPR scan image and make it difficult to assess rock fracturing.
In this case study, we explain how the Reutech Sub Surface Profiler (SSP) overcame the challenge of GPR scanning through mesh and suggested a technique for using the SSP to assess preconditioning on a development face.
By means of an example, consider a microwave door using a metal mesh screen to block dangerous electromagnetic radiation but, allowing visible light to pass through. The diameter of the holes in the door’s lattice is much smaller than the wavelength used for heating food. Similar to a microwave door, certain GPR wavelengths are too long to pass through mining mesh and the signal is filtered or blocked.
