Studies of Changes in the Electrical Resistivity of Rocks of the Tashtagol Mine in a Critical Rock-bump Hazardous State Based on the Kinetic Concept of Solids Destruction

Main hypotheses of the occurrence of seismic events centers, including rock bumps are presented. Equations of kinetic theory of strength are given. A two-stage kinetic model of crack accumulation and catastrophic destruction of rocks is formulated. It consists in the fact that at the first stage of the rock bump preparation there is a diffuse accumulation of cracks, and at the second — merging of cracks, appearance of enlarged cracks and formation of the destruction center. The results are presented concerning the theoretical and laboratory measurements of change of specific electric resistance of the host rocks and ores of iron ore deposit at mechanical loading and destruction. It has been shown that the relative change of specific electrical resistance of the low conductive rocks depends significantly on the ratio of electrical resistance of the rock itself and charged zones near the surface of the incipient cracks during rock loading. With the accumulation of cracks in the process of mechanical loading of the host rocks of the Tashtagol mine, the number of charged point defects of the structure on the crack edges increases. Specific electrical resistance of such rocks decreases with the accumulation of the number of cracks. In the ore bodies and magnetic iron ores, on the contrary, with increasing disturbance, the electrical resistance increases. There is regular change in the electrical resistance of rocks in the intermediate and limit states. For ores and magnetic iron ores, the critical change is 40 %, and for the host rocks with high electrical resistance — 28–37 %. Obtained values of change of the specific electric resistance in the rock critical state can be used for prediction of the rock bumps.