New approaches to the assessment of stability of rock rock arrays

Abstract

When summarizing the results obtained on the stability of rock masses a discrepancy was found between the parameters of the strength properties of rock formations, determined according to existing methods and state standards, to their values under natural conditions. As a result of the studies, the degree of geomechanical knowledge of the rock mass of the Gaisky underground mine is significantly increased. Based on the numerical simulation of the stress-strain state of the ore and rock mass, the rationale for the optimal mining of reserves at a depth of -830 / -1390 m was substantiated. The main compressive stresses of the Gaisky deposit act in the sub-latitudinal direction along the axis of the chambers, creating stresses exceeding 100 MPa on their outcrops. If the compressive strength of the massif is up to 100 MPa, found by known methods, ore masses of the third stage (pillars) below the -910 m horizon should be destroyed. In assessing the stability of pillars (chamber walls) in the last 3 years, in some cases, disagreement arose. The calculated stresses exceed the maximum allowable ones, but the pillars (chamber walls) remain stable. It justifies the correction of the obtained values of the ultimate strength of rocks with correction factors and the introduction of the definition of reduced strength (227 MPa), in which the roof, walls of the chambers and pillars are in a stable state. As a result of the study, the obtained values of the stress state of the rock mass and its strength characteristics more realistically reflect the predicted destruction or stability of the rock mass at the mine. The performed studies contribute to a more justified adjustment of mining technology parameters while ensuring the safety of mining operations.