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Date submitted2019-03-11
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Date accepted2019-05-06
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Date published2019-08-23
Estimation Method for Vector Field Divergence of Earth Crust Deformations in the Process of Mineral Deposits Development
- Authors:
- B. T. Mazurov
- M. G. Mustafin
- A. A. Panzhin
An essential requirement for effective and safe deposit development is good geomechanical software. Nowadays software packages based on finite element method are used extensively to estimate stress-strain state of the rock mass. Their quality use can only be assured if boundary conditions and integral mechanical properties of the rock mass are known. In mining engineering this objective has always been achieved by means of experimental observations. The main source of information on initial and man-induced stress-strain state of the rock mass is natural measurement of displacement characteristics. Measurement of geodetic data (coordinates, heights, directions) in the period between alteration cycles allows to plot a field of displacement vectors for the points in question. Taken together, displacement vectors provide information on the objective stress-strain state of the Earth crust. Basing on it, strain tensors, displacement components, directions and rates of compression and tension can be calculated in the examined area. However, differential characteristics of any physical vector field – namely, curl and divergence – need to be taken into account. Divergence is a single value (scalar) associated with a single point. Vector field as a whole can be described with divergence scalar field. Divergence indicates the sign (positive or negative) of volume changes in the infinitesimal region of space and characterizes vector flux in the nearest proximity and in all directions from a given point. In the paper authors propose a method to estimate divergence using discrete geodetic observations of displacement occurring on the surface of examined territory. It requires construction of formulas that model vector field for any point of the area. It is proposed to use power polynomials that describe displacement in three directions (x, y, z). These formulas allow to estimate field vectors in any given point, i.e. to form vector tubes. Then areas of input and output cross-section, as well as divergence values are calculated. This increases the quality of geodetic observation and provides opportunities for more precise modeling of the rock mass disrupted by mining operations, using modern software packages.
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Date submitted2019-03-25
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Date accepted2019-05-23
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Date published2019-08-23
Assessment of Rock-Burst Hazard in Deep Layer Mining at Nikolayevskoye Field
The paper presents results of conducted research using regional and local methods of forecast and control over geomechanical state of the rock mass at burst-hazardous Nikolayevskoye field, located in a geodynamically active region. The study subject is the ore mass of Nikolayevskoye field, characterized by man-induced and tectonic disturbances and high geodynamic activity. The aim of research was practical implementation of methods and instruments of forecast and control over geomechanical state of the burst-hazardous rock mass and safety improvement of mining operations. Exploitation practice of burst-hazardous fields demonstrates that forecast accuracy of hazardous rock pressure demands cutting-edge multi-level systems, where local methods and tools complement regional ones. A regional forecast of rock-burst hazard at Nikolayevskoye field was performed by means of seismoacoustic method using automated control system for rock pressure (ACSRP) «Prognoz-АDS». Local forecast was carried out using «Prognoz-L» device, geophysical (sample disking) method and visual observations of dynamic pressure manifestations in the mining tunnels. Quality assessment of stress-strain and burst state of the rock mass was performed using specialized software «PRESS 3D URAL». Integration of engineering and geomechanical data in the process of conducting research guarantees a relevant assessment of rock-burst hazard in various areas of the field at various stages of its development. Practical verification of the system, where local methods and tools complement regional ones, demonstrated satisfactory results at Nikolayevskoye mining plant, which makes it recommendable for other mining facilities extracting ore at great depths under similar conditions of active geodynamic processes.