ABSTRACT
The development of mineral deposits both by open and underground mining methods is always accompanied by the mining-induced stress field formation in the rock mass. The specificity of such stresses occurs in the form of their concentration or release in the geological medium structures. The rock mass in such conditions is subjected to permanent loadings and unloadings. This influence also results in the change of rock properties.
The hard rock mass is characterized by high strength and deformation parameters. However, the watered areas (aquifers), the structural discontinuities of different rank and the water-soluble minerals along with permanent loadings and unloadings in the rock mass can cause dynamic fracturing of rocks. In this regard it is important to study the variation of rock properties under the change of loading character under the water-saturated conditions.
The paper presents the results of laboratory studies on hard rock samples (carbonatite, fenite and gneiss) from the Kovdor deposit under uniaxial stress state with the change of their water-saturation time (from 1 to 13 days). A series of deformation tests in the form of loading and unloading up to a value of 30% of the compressive strength with subsequent fracturing of samples were performed simultaneously with the water-saturation process.
The dependence between the change of physical-mechanical properties of studied rocks and the quasistatic alternating loadings was established by comparing the test results. The authors have determined a degree of influence of water-saturation time increase on the acceleration of rock samples’ fracturing and the possibility of dynamic rock pressure occurrences in the hard rock mass.
