Prediction of the Stability of the Loaded Rock Based on the Acoustic Emission Characteristics of the Loaded Rock Based on Data Mining

The rock masses that occur in nature are damaged and unstable due to the impact of rock burst, coal and gas outbursts, and other human mining activities, posing a major threat to human life and safety. In the light of the early warning of the danger of the loaded rock mass, this paper adopts acoustic emission (AE) device to analyze the AE signal characteristics and damage laws of the loaded rock under different stress levels. Then, based on the AE signal characteristics of the loaded rock, data mining technology is used to construct a model to predict the failure and instability of the loaded rock mass and, finally, verify the reliability of the prediction model based on data mining. The results show that the AE signal characteristics of red sandstone under uniaxial load are related to the magnitude of the bearing stress. Before the plastic deformation stage, the AE energy and the cumulative count per second are both small. After the loaded rock enters the plastic deformation stage, the AE energy and the cumulative count per second both increase sharply. After the AE energy is greater than 500 mV ∗ ms and the cumulative count per second is greater than 150, the loaded rock mass will issue an early warning signal. The research results can provide a reference value for the safe production of the project site and the dangerous early warning of the loaded rock mass.

Spatial Distribution of Triggered Earthquakes in the Conditions of Mining-Induced Seismicity

Abstract—The spatial distribution of the triggered seismic events in mining conditions in the tectonically loaded rock masses is studied using the example of seismicity in the Khibiny Mountains. It is shown that the distribution of distances from the triggering to triggered events, on average, obeys the power-law with a parameter independent of the magnitude of the triggering event. The model of the maximum distances from a triggering event’s hypocenter to the triggered shocks expected with a given probability is derived. It is shown that the model is consistent with the real data. Based on the error diagram analysis, the guidelines are proposed for the practical use of the model.

Substantination of hydromechanical parameters of water regulation using mine pillars during mines closure

Purpose. Substantiation of hydromechanical parameters that make it possible to control the safe ratio of hydrodynamic levels in a mine shaft and a rock mass when closing mines using submersible pumps. Research methodology. An experimental-analytical method was used, which consists in the formation and analysis of data from field tests of fractured porosity, permeability and the position of groundwater levels in hard sandstones around mine shafts with concrete support. Research results. It has been established that the hydromechanical state around a mine shaft in stable water-bearing rocks is characterized by the development of mutually competing processes of nonlinear decrease in the permeability of the loaded rock contour and hydrogeomechanical unloading of structural elements of water-bearing rocks and filter attachment. The values of the hydrogeomechanical unloading of the shaft attachment in the range of 0.054 - 6.125105 Pa are close to the tensile strength limit of the "concrete-water-bearing rock" contact, which indicates the danger of its collapse. Scientific novelty. The problem of combining the elastic viscometric load of the rock mass attachment and the hydrodynamic planar-radial flow to the wellbore is solved, where the hydrogeomechanical state in stable water-bearing rocks is characterized by the development of mutually competing processes of nonlinear decrease in the permeability of the loaded rock contour and hydrostatic unloading of structural elements of the water-bearing rocks and filters. Practical value. The obtained solutions and their analysis explain the discrepancy between the calculated (standard) loads on the fastening, which is known from practical experience, and actually measurable values, and also have significant practical significance. The established fact of the approximation of the value of hydrogeomechanical unloading of the stovol attachment to the tensile strength of the contact "concrete - water-bearing rock" is dubious and requires a decrease in the hydrodynamic deflection to the mine stovol when controlling the process of flooding with submersible pumps.

THE RESULTS OF STUDIES OF THE DEPENDENCE OF THE PERFORMANCE OF THE VIBRATING TWO-SHAFT CENTRIFUGAL MODULE ON THE MODE AND DESIGN PARAMETERS

The article presents a new design of a vibrating twin-shaft centrifugal module designed for grinding and classification of rock mass. In this design, in addition to grinding, the operation of classification or screening of the crushed mass was added, which does not allow its regrinding and increases the productivity of the device. This is achieved by installing in the bottom of the chamber grinding mesh with cells in accordance with the required class size. At the same time, the classification process is intensified by the presence of vibration from vibration exciters fixed on the camera body and the installation of the camera on elastic supports. The reciprocating horizontal vibrations of the chamber with a given amplitude and frequency contribute to the segregation of the crushed rock mass in the bed by size, which positively affects the efficiency of classification and grinding. The presence of vibration helps to unload the oversize product from the grinding chamber. Also, the article considers experimental studies performed on a vibrational two-shaft centrifugal module to determine the dependence of the performance of a given design on five variable factors: rotor shaft revolutions (n, rpm), size of the loaded rock mass (Δ, mm), rock mass strength (σ, kg/mm2), camera vibration frequency (ω, rpm) and its vibration amplitude (A, mm). Studies have shown the efficiency and increased productivity of the new design in relation to a centrifugal disintegrator without a classification grid and vibration. The results of the work allow us to recommend the design under study for the manufacture of an experimental sample according to the given initial requirements, and the established dependences (Q = f (n, Δ, σ, ω, A) make it possible to develop a mathematical model of the grinding process in this setup to calculate the required parameters.

Badanie wpływu dodatku azotanu(V) amonu na właściwości wybuchowe masy aktywnej Rocksplittera

The Rocksplitter’s active mixture, which consists of sodium chlorate(V) (SC) and oil, is characterized by the lack of detonation capability and the presence of solid sodium chloride particles in the explosion products that reduce the volume of gas. The reduction of gaseous explosion products under certain conditions may be a disadvantage, reducing the effectiveness of Rocksplitter’s impact on the loaded rock mass, which may be a significant limitation in the use of this product. Replacing some of the sodium(V) chlorate(V) with ammonium nitrate(V) (AN) should partly eliminate this disadvantage. In this work, the results of research on selected detonation and explosive parameters of tertiary mixtures of SC - AN - oil are presented. The influence of grain size of AN was also investigated. AN was used granulated and ground. The ability to detonate, velocity of detonation and intensity of air blast waves in the functioning of the contents of individual components has been set.