Predicting underground mining impact on the earth’s surface

Abstract

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.