Evaluation of the geomechanical state of a rock mass in working deposits in a cryolithozone

The statement of the problem of determining the stress-strain state of support and rock mass around the mine working in unstable rocks, in case of voids filling with phenol resins is proposed. The initial parameters used in the calculations correspond to the conditions of mining ore deposits in East Kazakhstan. The distribution character of stress fields in the support and their change depending on geometric sizes of the area filled with phenol resins is determined. It is shown that using phenol resins causes formation of a uniform pressure of surrounding rocks on the arch part of the support and facilitates an increase in its stability.

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DEFINITION OF MAIN CRITERIA FOR EFFICIENT OPERATION OF DEGASSING WELLS

SCIENTIFIC PAPERS OF DONNTU Series: “The Mining and Geology” ◽

10.31474/2073-9575-2020-3(23)-4(24)-74-77 ◽

2020 ◽

pp. 74-77

Author(s):

Artem Merzlikin ◽

◽

Victor Nazimko

Keyword(s):

Rock Mass ◽

Radial Displacement ◽

Aerodynamic Drag ◽

Aerodynamic Resistance ◽

Bedding Plane ◽

Efficient Operation ◽

Working Face ◽

Geomechanical State ◽

The Stability ◽

Definition Of

Purpose. Research and substantiation of the main criteria for sustainable and efficient operation of degassing wells. Methodology. In the work, the method of mine observations was used to study the geomechanical state of the rock mass around the development workings and the operating long working face. Results. The directions and magnitudes of tangential deformations in the rock mass following the movement of the working face are investigated to ensure the safety of the section of the degassing well. It has been found that with an inclined wellbore, the diameter in the direction of inclination increases inversely to the value of the cosine of the inclination angle. It is justified to ensure the safety of the well section in the area of intense tangential deformations of the massif and its efficiency in general, by choosing a sufficient diameter of the well degassing and its angle of inclination to the bedding plane. Originality. The main four criteria of stable and efficient operation of the degassing well have been determined and substantiated, which take into account the outrageous deformations of the massif, the limiting level of rock pressure, the value of concentrated displacement and radial displacement of rocks around the development workings from which degassing wells were drilled. It was found that with a decrease in the diameter of the borehole degassing section by an amount not exceeding the borehole radius, the local aerodynamic resistance in the narrowing section increases insignificantly. However, the further section of the wellbore increases its aerodynamic drag abruptly, and the well flow rate decreases many times. Practical value. Based on the formulated criteria and the identified factors, it is planned to develop measures to ensure the stability of the degassing wellbore and the efficiency of its functioning. Key words: degassing; risk; well deformation.

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ASSESSMENT RESULTS ON GEOMECHANICAL STATE OF NEAR-WALL ROCK MASS IN OPEN-PITS OF THE KOLA REGION BY INTEGRATED INSTRUMENTAL METHODS

15th International Multidisciplinary Scientific GeoConference SGEM2015, SCIENCE AND TECHNOLOGIES IN GEOLOGY, EXPLORATION AND MINING ◽

10.5593/sgem2015/b13/s3.015 ◽

2011 ◽

Author(s):

Anatoliy Kozyrev

Keyword(s):

Rock Mass ◽

Wall Rock ◽

Kola Region ◽

Geomechanical State ◽

Instrumental Methods ◽

Near Wall ◽

Assessment Results

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http://www.mining-science.ru/download/2020/3/04.pdf

Izvestiya vysshikh uchebnykh zavedenii Gornyi zhurnal ◽

10.21440/0536-1028-2020-3-31-38 ◽

2020 ◽

pp. 31-38

Author(s):

Nikolai Cherdantsev ◽

Keyword(s):

Rock Mass ◽

Elasticity Theory ◽

Granular Media ◽

Limit State ◽

Coal Pillar ◽

Elastoplastic Problem ◽

Coal Bed ◽

Problem Solution ◽

Geomechanical State ◽

Exterior Boundary Value Problem

Introduction. Reliable forecasts of pillars geomechanical state are required to ensure rhythmic and safe work when mining a coal bed. Research aim is to construct a state model of the coal pillar located between the headways, based on the fundamental methods of elasticity theory and mechanics of a granular media, carry out a computational experiment within the model, and analyse the results. Methodology. The stress field in the coal pillar has been constructed in the course of solving the elastoplastic problem. By replacing the ultimately stressed marginal zone of the bed with the stresses which act within the zone, the problem has been reduced to the second exterior boundary value problem of elasticity theory and has been solved by the boundary element method. Ordinary and special Coulomb–Mohr criteria simultaneously fulfilled for the coal bed and rock mass contact are the criterion of the limit state onset. Actual pillar load is determined by integrating the vertical stress curve along the bed roof, which has been obtained from elastoplastic problem solution, while the ultimate load is determined from the condition that the whole pillar is in ultimately stressed state. Results. The dependence between the safety factor of the pillar between two identical headways, determined by V. D. Shevyakov method, and the growth of its width represents a graph in the form of a monotonically increasing curve. The curve flattens as soon as the depth increases. Summary. The results from the developed model of coal rock mass geomechanical state can be successfully used as coal pillar strength forecasts.

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