An analysis of the world experience in the development of potash deposits shows that the main problems arising during their development are a high level of mineral losses, an increased risk of flooding of mine workings as a result of water-proof layer discontinuance and the development of emergency water inflows in the mined-out spaces. Reduction of potash ore losses can be achieved by using a long-pillar mining system, but this method is limited by the peculiarities of the geological structure of the potash deposits and the need to preserve the continuity of the water-proof layer during its underworking. The safety of underworking of the water-proof layer can be improved by using the stowing of the developed longwall space. However, the question of the influence of the stowing on the height of the zone of water supply cracks development remains little-studied. The world experience of stowing the developed spaces in the development of layers with long pillars is analyzed and the technology of placing the stowing masses, which can solve these problems, is proposed. The considered technology and the proposed solutions are supported by laboratory tests of stowing materials and mathematical modeling of deformation zones in the overlying rocks.
The article focuses influence of disjunctive dislocations on parameters of secure zones on flat-lying adjacent coal seams is considered.
Estimation of the strain-and-stress state and displacement of the waterprotective layers in vicinity of mining excavations in conditions of SKRU-3 mine (Uralkali Group) is done. It is shown that loadings on pillars on layer Kr.II exceed 15-20 % loadings on layer AB.
An example of application of finite element method in rock mechanics is presented. Parameters of stress-and-strain state of rocks in vicinity of a shallow transport excavation are estimated. Some results of numerical modeling are presented.
Numerical experiment is characterized as one of the research methods in rock mechanics. Definition of the method is given. Specifics of rock mass as a research object are described.
Approaches to selection of technological mining schemes based on selective potash seam extraction are described. Progressive technological mining schemes for potash mining company «Belaruskaliy» and the geological conditions of the IV potash horizon are reviewed. Basic aspects of the geomechanical substantiation of parameters of technological mining schemes for conditions of the new potash horizon in the presence of influence of the overlying horizons are also presented. Guidelines for substantiation of progressive mining methods for the conditions of the IV potash horizon (Third Mine, «Belaruskaliy») are developed on the basis of the modeling of the stress-and-strain state of the rocks.
The scheme of approach of evaluation of the stability of underground structures with account for seismic activity of rock strata is introduced. Some aspects of estimation of stability of underground structures under dynamic loads are also present. Methods of choosing the safe parameters of underground mining with account for seismic and tectonic activity of rocks are shown.
Technological scheme of selective extraction of a complex thick potash seam on the basis of cutting machine «Bucyrus Model 25 M0» is proposed. Stable pillars’ width and room dimensions are calculated. Economical effect is also presented.
Methodical approaches for substantiation of rational development and mining of new potash horizon are presented in the article. The state of ore mines of «Belaruskali», geological conditions of the IV potash horizon, main aspects concerning geomechanical substantiation of development parameters are reviewed. Recommendations on development of IV potash horizon at the Third mine («Belaruskali») are given on the basis of analysis of stress and strain state of the rock strata.
On the example of Starobinskoye deposit the criteria determining the choice of development systems and possible ways to increase the extraction of potassium reservoirs are considered. Different principal schemes of sylvinite extraction from pillars by auger drilling technology are proposed. The method of geomechanical justification of the parameters of pillar extraction is developed. The results of the estimation of the stress-strain state (STS) of pillars and their host massif for the characteristic time moments of the pillar delineation of mined-out spaces are given.
Taking into account the theory of formation of blowout-hazardous zones of dip trough type, the average statistical parameters of cavities of artificially initiated salt and gas emissions were determined for the conditions of the Starobinskoye field. Dependencies for determining the location of the center of the blowout zone in the vertical and horizontal planes are derived. The way of transition of emission-hazardous zones during excavation of the Third Potash Seam at full capacity is concretized. The correlation between the slope angle of the advanced drift with the initiation cut, which serves for artificial decoupling of the release, and the geometric parameters of the release zone was found. When conducting the advance face with the initiating jaw in the direction to the center of the trough core during the initiation of the outburst, taking into account this dependence will reduce its intensity, increase the safety of mining operations, as well as improve the economic indicators of the method of transition of the outburst-risk zone by the longwall.
Statistical analysis of the results of crossing by mining works of geological disturbances of dip trough type at PA Belaruskali has been performed. I.A. Odessky's theory on formation of dip troughs is considered and specified. On the basis of the basic method, used in the mines of the Association and the described theory of mound formation, the method of artificial initiation of coal and gas blowout in the longwall at excavation of the Third Potash Seam of Starobinskoye deposit at full capacity was developed. Parameters of the method are determined taking into account the geometric structure of the dipping trough. Immediately before the initiation of drilling and blasting operations a conductive channel is formed for salt and gas ejection into the mined-out space. For the given method, taking into account geological structure of the troughs and physical and mechanical properties of salt rocks, a standard BWR passport for artificial initiation of salt and gas ejection with limitation of the ejection intensity is calculated. According to the passport, the blasting is carried out with three deceleration stages, at that the central borehole is not charged. The results of calculations of parameters of works on initiation of sudden emissions in zones of geological disturbances are presented.
