MEASUREMENT ACCURACY WHEN MEASURING THE DEFORMATION OF MINE WALLS BY TOTAL STATION

Abstract

The paper has described the measurement accuracy when measuring the deformations of rock mass around mines. The projections of the displacement vector for displacing the deformation control benchmarks embedded in the cross section of the mine on the section plane are taken to be rock mass movements. The deformation control benchmarks are drive wedge anchors embedded along the perimeter of the section in the walls and roof of the horizontal mine near the mine face. Measurements are carried out using a high-precision total station. The accuracy in position of the deformation control benchmarks depending on the position of the benchmark relative to the instrument has been theoretically estimated on the basis of the passport characteristics of a high-precision total station with a root-meansquare measurement error being equal to one angular second. The obtained values of the root-meansquare error in determining the position in the section plane fall in the range from 0.5 to 0.85 mm.
To verify the theoretical estimates obtained in practice, we have measured the convergence of mine workings at the operating enterprise. Field measurements made in hard rocks have recorded displacements of the deformation control benchmarks
0–4 mm. The estimation of the accuracy for the measurements carried out using the Bessel formula shows that the root-mean-square error of the position of the benchmarks in the measurements with two complete actions is about 0.4 mm. It is shown
that the obtained relative error in determining the deformation is 1/10000. The data obtained indicate that the actual measurement errors of high-precision total stations under mine conditions, while observing the measurement technique are close to theoretical values. This makes the application of this measurement method suitable for monitoring the changes in the stress field of rock mass around the mines and for determining the convergence of mines during the mine face advance to determine the characteristics of the natural stress field in virgin rock