Technique for assessing the stress state of a rock mass by a multicomponent displacement sensor using the overcoring method

Abstract

Relevance. Currently, the mining industry is at the beginning of a new stage of development, which corresponds to the extraction of minerals at great depths in difficult conditions. Based on this, an uncertainty is formed in the assessment of the parameters of the stress state of the rock mass in which mining operations are carried out, which contributes to the growth of emergency situations in underground conditions. The method of overcoring is able to provide quantitative and qualitative information about the stress state. The purpose of the research – substantiation of the methodology for assessing the stress state of the rock mass by the method of overcoring, which includes two main stages: 1 – field tests; 2 – processing of field test data. Research methodology. The method of overcoring is based on measuring the displacements of the points of the walls of the measuring well with a multicomponent displacement sensor as a result of creating an annular gap (formation of complete unloading). Data processing is carried out by two main approaches: 1 – numerical modelling; 2 – analytical calculation. Results. The concept of carrying out work on the assessment of the stress state of the rock mass by the method of overcoring is described. Detailed information about the field test is provided, namely the sequence of measurements and the necessary equipment. A step-by-step algorithm for processing data obtained as a result of field tests based on numerical modelling and analytical analysis has been created. Conclusion. The technique presented in this paper was tested at the deposits of AO Apatit and PAO Norilsk Nickel and showed correct quantitative and qualitative results, according to the stress state of the rock mass.