Some problems of the express method of rock strength determination
Introduction. Within the course of mining, rock massif heterogeneity calls for constant operational control of its changing state and characteristics. One key parameter of the massif under investigation is the compressive strength. Main way of rock strength properties determination currently is laboratory testing of the prepared samples by means ofpresses. One alternative way of geomaterials ' compressive strength on-line measurement is the method of elastic rebound with a sclerometer (Schmidt's hammer). Research methodology. Research object are rocks of Dzhetygarinsky pit surface massif where hand specimen were selected for testing. Compressive strength was determined by the main method and the alternative method. Research results. Laboratory research results at presses have shown some discrepancy between the obtained values and Schmidt's hammer readout. However, it should be noted that the results obtained in the laboratory conditions are the most exact and reliable. Data discrepancy is caused by the presence of structural and textural inhomogeneity of the hard rock under investigation. Comparative analysis and statistical data processing for various types of rock at Dzhetygarinsky massif determined calibration curves and distinguished the transition coefficients of compressive strength from sclerometer readout to laboratory values.