Purpose.Increasing the load-bearing capacity of metal arch supports used to maintain the mine workings due to strengthening in places with the highest bending moment. Methods. The stress-strain state of the rock mass and support is analyzed using the ANSYS software package. The problem is studied in three variants: a support without strengtheners, a support with one strengthener in the area with the maximum bending moment, and a support with three strengtheners in the areas with the highest bending moments. To determine the bending moments and normal forces in a three-section metal arch support, the finite element method is used for specific and existing conditions, which is followed by the selection of the required standard size of the support. Findings. The conducted research gives reasons to believe that the proposed variant for increasing the load-bearing capacity of the support, made from a special replaceable rolled profile (SCP), can significantly improve the state of mine workings. Obviously, the proposed solution can be applied not only to arch supports, but also to other structures of rolled metal support. Originality. The pattern of changes in the values of internal forces arising in metal arch frame supports, depending on the deformation characteristics, the location of the strengtheners, as well as on the geometric characteristics of the mine working and the ratio of lateral and vertical loads on the support, has been determined. Practical implications. The proposed variant for increasing the load-bearing capacity of the support can be used to sustainably maintain mine workings in difficult mining-geological conditions of the Karaganda Coal Basin mines.
Purpose. Developing an efficient and high accuracy methodology of observing the earth surface deformations when mining minerals by the underground method. methods. Experimental graphoanalytical methods as well as mathematical modeling were applied. findings. There is presented a methodology and results of processing the data of observations of the earth surface displacements when mining coal at Kostenko mine of the Coal Department of ArcelorMittal Temirtau JSC, Kara ganda Coal Basin. The displacement measurements were performed at points of the small geodetic network using the GNSS technologies with accuracy acceptable for the satellite geodetic network of class 1. The results confirm the GNSS methods effectiveness in studying the earth surface displacements in coal mine conditions. Displacement vectors of the GNSS points were determined; numerical values of the relative vertical and horizontal displacements of the points were obtained. originality. A new technique for making geodesic measurements was developed when studying the earth surface displacements during its underworking by means of building local small geodynamic networks. For the first time the observations of the earth surface displacements due to its undermining in the territory of the Karaganda coal basin were carried out not along the profile lines but as a result of a detailed surface survey. Practical value. The proposed method for performing geodetic measurements using the GNSS technology to study the earth displacements has made it possible to determine the parameters of the displacement process with a high degree of accuracy and can serve as the basis for organizing geodetic monitoring at all the mines of the Kara ganda coal basin. The main tool for monitoring manmade processes was a network of specially designed benchmarks in the field. With systematic monitoring, when initially there are implemented the measures to form a geodynamic polygon, the greatest degree of prediction of the risks of field exploitation is achieved.
Purpose. Development of a digital model of the stress-strain state of a rock mass during the extraction of coal by an underground method to predict the displacement of the earth’s surface. Methodology. The proposed technique is based on modeling the stress-strain state of a rock mass using the finite element method. Computer simulation of the stress-strain state of the rock massif was carried out in the area of lavas worked out in previous years in layers with the index K of the Karaganda suite of the mine named after Kostenko of the Karaganda coal basin, where instrumental surveying measurements were previously made to monitor the vectors and numerical values of the displacements of the earth’s surface undermined by mining. Findings. The reliability of the obtained finite element model of a rock mass for predicting the process of displacement of rocks and the earth’s surface is confirmed by the results of full-scale instrumental mine surveying measurements on the earth’s surface. Originality. For the first time, a method has been proposed for predicting the shifts of points on the earth’s surface, taking into account the physical and mechanical properties of rocks, based on a finite element model of a rock mass. A new approach was applied to assess the reliability of the model of the stress-strain state of a rock mass based on a comparison of the results obtained with the data of instrumental mine surveying. Practical value. A technique for computer simulation of the stress-strain state of a rock mass during the extraction of hard coal at the mine named after Kostenko, owned by one of the world’s leading steel producers, JSC ArcelorMittal. For modeling, a site was chosen in the area of lava mining along the coal seams of the Karaganda Formation of seams, starting from the K18 seam to the K10 seam, that is, a rock mass with a depth of more than 700 m. Previously, within this area a series of instrumental surveying observations was carried out of the displacement of the earth’s surface during the working out of these lavas using the method of roof management – complete collapse. The obtained values of vertical displacements of a point on the earth’s surface according to the results of computer simulation of the stress-strain state of a rock mass correspond to the data of field mine surveying observations of displacements of the same point, which confirms the reliability of the constructed model.
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