EXPERIMENTAL STUDY ON TENSILE AND COMPRESSIVE MECHANICAL PROPERTIES OF ROCKS FROM DIFFERENT DEPTHS AT A DEEP MINE

The physical and mechanical properties of rocks undergo changes with burial depth. To explore the influence of different burial depths on these properties, surrounding rock cores from both the hanging wall and footwall were drilled at a lead-zinc mine in Yunnan, spanning four depths(ranging from 900 to 1200 m). Uniaxial compression and Brazilian splitting tests were conducted under varying water content conditions(natural state and saturated state). The results indicate that the rock material composition and structure remain similar within the studied depth range. As the rock burial depth increases, the density, p-wave velocity, uniaxial compressive strength, tensile strength, and elastic modulus of rock samples show a slight increase, while Poisson's ratio initially increases and then decreases. The water content conditions of the samples significantly impact their mechanical properties. After water saturation treatment, the compressive strength, tensile strength, and elastic modulus of samples at different burial depths are notably reduced, and Poisson's ratio experiences a marked increase. The order of water sensitivity for each parameter is compressive strength>elastic modulus>Poisson's ratio>tensile strength. This study provides a clear explanation for the variation in tensile and compressive mechanical properties of surrounding rock at different burial depths in deep mines.