Determination Of Rock Discontinuity For Prediction of Blasting Performances Using Quantitative and Qualitative Parametero

Abstract

The study assesses quantitative and qualitative parameters of rock discontinuity in some selected quarries in Ekiti and Ondo state for prediction of blasting performances. Scanline method of discontinuity measurement was used to measure 200 discontinuities from RCF granite quarry, 99 discontinuities from Kopek granite quarry and 303 discontinuities from Samchase granite quarry at a distance of 20m, 25m and 20m from each quarry bench face. Quantitative and qualitative discontinuities parameters were measured and the values obtained were recorded in frequency table with class intervals of 10-100 for dip angle, 0.01 - 0.10m for spacing and 0.01 - 0.25m for persistence. The graphs of frequency against discontinuity values were plotted. The results show that the mean spacing of the three granite quarries outcrop (357mm, 337.8mm and 343.4mm) were within 200mm - 600mm [1]discontinuity spacing classification table which indicates that the outcrops were moderately spaced. Also, the persistence values of the granite quarries outcrop (1.0019m, 1.4205m and 1.4205m) were within 1m - 3m [1] discontinuity persistence classification table which indicates that the outcrops have low persistence. The quarries have rock masses of high uniaxial compressive strengths (152.320MPa, 132.256MPa and 120.973MPa) and high point load strengths (13.732MPa, 9.713MPa and 1.953MPa). The moderately spaced outcrop, low persistence outcrop and high strengths outcrop indicates good blast performance for the three quarries.