Far-field in-situ stress magnitudes play a significant role in the type and level of geotechnical challenges that an underground mine can face during the life of the mine. Several methods have been introduced to the mining industry for in-situ stress determination, e.g., overcoring, flat jack, mini-frac, and so on. Each of these methods has its limitations due to their underlying assumptions and field technical difficulties. The Canadian hardrock mining industry requires reliable and cost-effective stress measurement techniques. The sleeve fracturing method seems to be promising when it comes to measuring stress in hard rocks. 

This paper presents the results of a series of lab experiments conducted to evaluate the effectiveness of this method. The stresses applied to the samples simulate the conditions at shallow depths. The fracture pressure onset is detected using diagnostic plots. In addition to fracturing pressure, the fracture opening is also measured to confirm the results. The measurements are compared to the theoretical values calculated from stress concentration around a circular opening.