The explosion caused by detonation of explosive materials is followed by release of a large amount of energy. Whereby, a greater part of energy is used for rock destruction, and part of energy, in the form of seismic wave, is lost in the rock mass causing rock mass oscillation. Investigations of the character and behavior of the pattern of seismic wave indicate that the intensity and nature of the seismic wave are influenced by rock mass properties, and by blasting conditions. For evaluation and control of the seismic effect of blasting operations, the most commonly used equation is that of M.A. Sadovskii. Sadovskii's equation defines the alteration in the velocity of rock mass oscillation depending on the distance, the quantity of explosives, blasting conditions and geological characteristics of the rock mass, and it is determined based on trial blasting for a specific work environment. Thus, this paper offers analysis of the method for determination of parameters of the rock mass oscillation equation, which are conditioned by rock mass properties and blasting conditions. Practical part of this paper includes the experimental research carried out at Majdanpek open pit, located in the northern part of eastern Serbia and the investigations carried out during mass blasting at Nepričava open pit, located in central Serbia. In this paper, parameters n and K from Sadovskii's equation were determined in three ways-models in the given work environment. It was noted that, in practice, all three models can be successfully used to calculate the oscillation velocity of the rock masses.
This paper describes an investigation into the use of three power plant wastes: fly ash, flue gas desulphurization gypsum, and bottom ash for subbase layers in road construction. Two kinds of mixtures of these wastes with Portland cement and water were made: first with fly ash consisting of coarser particles (<1.651 mm) and second with fly ash consisting of smaller particles (<0.42 mm). The mass ratio of fly ash-Portland cement-flue gas desulphurization gypsum-bottom ash was the same (3 : 1 : 1 : 5) in both mixtures. For both mixtures, the compressive strength, the mineralogical composition, and the leaching characteristics were determined at different times, 7 and 28 days, after preparation. The obtained results showed that both mixtures could find a potential use for subbase layers in road construction.
Coal reserves in Serbia represent an important strategic energy raw materials on which in the coming decades will be based energy development in Serbia. Coal mining in Serbia is performed by surface, underground and underwater mining, and within each of them there are also the coal preparation facilities. Underground mining is done in the scope of the JP PEU Resavica, which includes eight active mines: Bogovina, Rembas, Vrška čuka, Štavalj, Ibar, Soko, Jasenovac and Lubnica. Surface mining is carried out as part of a JP EPS. Mining operation is done in mining basin Kolubara and Kostalac which are supplier of three thermal power plants: Kolubara, Nikola Tesla and Morava. Underwater mining and preparation of coals in Serbia has been done in Kovin coal mine. Coal production, processes of preparation and quality for all active mines in Serbia are presented in this review paper.
Abstract:In order to evaluate and control the seismic effect of blasting, as well as its planning, it is required to determine the soil oscillation law, with the strike/mining facilities to be protected. One of the most commonly used equations is that of M.A. Sadovskii, defining the law of alteration in the oscillation velocity of the soil depending on distance, the explosive amount, and conditions of blasting and geologic characteristics of the soil; all of this being determined on the basis of test blasting for the specific work environment. In the Sadovskii equation two parameters, K and n appear and they are conditioned both by rock mass characteristics and blasting conditions. The practical part of this study includes experimental investigations performed in the Veliki Krivelj Open Pit in the Bor District located in Eastern Serbia and investigations carried out during mass mining in the Kovilovača Open Pit near Despotovac, Eastern Serbia. Thus this paper offers several modes for determination of parameters K and n in the Sadovskii equation. To determine the parameters in the Sadovskii formula, in addition to the usual least square method, two more new models were applied. In the models the parameters K and n were determined by applying the quotient of the relative growth of oscillation velocities and reduced distances for Model 2. The link between the parameters K and n is determined by applying the trapezoidal formula for finding the value of definite integral for Model 3. In doing so, it was noted that all three models can be used to calculate the oscillation velocity of the rock mass.
Relatively large deformations of the steel arch support in underground coal mines in the Republic of Serbia present one of the main problems for achieving the planned production of coal. Monitoring of the critical sections of the steel arch support in the underground roadways is necessary to gather quality data for the development of a forecasting model. With a new generation of 3D laser scanners that can be used in potentially explosive environments (ATEX), deformation monitoring is facilitated, while the process of collecting precise data is much shorter. In this paper, we used a combination of grey and stochastic system theory combined with an autoregressive process for processing collected data and the development of a forecasting model of the deformations of the steel arch support. Forecasted data accuracy based on the positions of the markers placed along the internal rim of support construction shows high accuracy with MAPE of 0.2143%. The proposed model can successfully be used by mining engineers in underground coal mines for steel arch support deformations prediction, consequentially optimizing the maintenance plan of the underground roadways and achieving planned production.
As a way of exploitation in mining operation, mass blasting has the more application. However, usage the large amount of explosives leads to increasing the negative blasting effects. By the negative blasting effects, we mean seismic effect of blasting, sound effect, scattering of blasted rock mass, etc. In order to protect environment from shock when performing blasting it is necessary to define rock mass oscillation equation for each working site. This paper offers the analysis of the method for defining parameters of the oscillation equation. To define parameters in the rock mass oscillation equation, we have used five models. The first model represents a usual model – method of Least Squares. The second model is based on the quotient of the value of the equal number of experimental data of oscillation velocity and corresponding reduced distances. The third model is based on defining parameters of oscillation equation by applying Lagrange’s theorem. The fourth model is based on defining parameters for oscillation equation by applying the quotient of relative oscillation velocity increments and reduced distances. As the result of numerous measuring’s there has been noted that the value of one of the parameters in the oscillation equation is within the limits from 1 to 3, however most frequently from 1 to 2. On the basis of this as well as on the basis of oscillation equation characteristic, the value of one parameter was adopted. Thus, we got a new rock mass 292 oscillation equation which is now simpler, and we designated it as the fifth model. On the basis of calculation on concrete example of mass blasting, it has been stated that all mentioned models may be used in order to calculate rock mass oscillation velocity
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