A Study Regarding the Application of the Refraction Microtremor (ReMi) Process in an Underground Mining Environment.

A study was conducted to determine the applicability of the Refraction Microtremor (ReMi) method in order to predict changes in rock characterization in an underground mine. ReMi involves acquiring noise data along a linear array of geophones. Data is processed to obtain shear-wave velocities underneath the array. The data for our study was collected at an underground gold mine in Nevada, and was analyzed using the SeisOpt® ReMi™ (© Optim, 2015). The data was collected using horizontal and vertical geophones, placed into the ribs of the drift in a horizontal plane, rather than the industry standard placement of vertical geophones into the ground in a vertical plane. In order to determine whether the changes seen actually exist, shear-wave velocities were measured in location of known rock characterization. These shear-wave velocities were then compared with the Rock Mass Rating (RMR) and previously published correlations between RMR and shear-wave velocity. In addition, the use of ReMi as a tool to determine the extent of voids underground was investigated. This can then be used to determine the extent of voids underground and help to distinguish locations where voids may be near above or below excavations