Purpose. This article proposes to analyze and determine the mining design for shallow-dip deposits hosted in poor quality rock. Methods. We used the UBC tool to find the optimal exploitation method, the Rock mass rating (RMR) and Q-system (Q) to determine the optimal mining stope and the recommended rock support, the numerical modeling by RS2 software with a variety of geotechnical, geometrical, and technical conditions to analyze the evolution of the unstable zone width and the maximum total displacement around the stope after excavation. Findings. The optimum mining method designated by the UBC tool for this type of deposit is the cut and fill. By projecting the obtained RMR and Q-system values on the design graph, it is concluded that the operating stope is located in the stable zone with a height of 3 m, and bolting support is recommended. The simulation by RS2 software reveals that the optimal mining design that can be used to mine shallow-dip vein deposits hosted in poor quality rocks consists of a 3 m high stope and a 75° dip with cemented backfill. Originality. This work presents a study to choose the most suitable underground mining method and mine design for shallow- dip deposits hosted in poor quality rock. Practical implications. In the mining industry, the success of operating an underground mine is conditioned by the selection of the appropriate method, of the mining design and dimensioning of a rock support adapted to the nature of the rock, and excavation geometry according to the type and nature of the deposit.

Purpose. To develop a new theory for the rocks destruction by blasting using a description of the formation processes of zones with various mass state around the charging cavity. Methods. The new theory for the rock mass destruction by blasting has been developed based on the use of the well-known elasticity theory laws and the main provisions of the quasi-static-wave hypothesis about the mechanism of a solid medium destruction under the blasting action. The models of zones of crumpling, intensive fragmentation and fracturing that arise around the charging cavity in the rock mass during its blasting destruction, depending on the physical and mechanical properties of the rock mass, the energy characteristics of explosives and the rock pressure impact, have been developed using the technique of mathematical modeling. Findings. Based on the mathematical modeling results of the blasting action in a solid medium, the mathematical models have been developed of the zones of crumpling, intensive fragmentation and fracturing, which are formed around the charging cavity in a monolithic or fractured rock mass. Originality. The rock mass destruction by blasting is realized according to the stepwise patterns of forming the zones of crumpling, intensive fragmentation and fracturing, which takes into account the physical and mechanical properties of the medium, the energy characteristics of explosives and the rock pressure impact. Practical implications. When using the calculation results in the mathematical modeling the radii of the zones of crumpling, intensive fragmentation and fracturing in the rock mass around the charging cavity, it is possible to determine the rational distance between the blasthole charges in the blasting chart, as well as to calculate the line of least resistance for designing huge blasts.

Purpose is to determine a function of the reduced expenditures connected with drilling-and-blasting operations, loading and hauling operations, and rock fragmentation depending upon the cost of machine-shift of the applied facility, its operation modes, hardness of rock being blasted, cost of the used explosive, and rock fragmentation quality based upon the developed optimization mathematical model. Methods. Method of statistical evaluation of natural blockiness structure of the rock as well as quality of its fragmentation by means of explosive energy has been applied. Statistical studies have been carried out concerning the basic indices of rock fragmentation depending upon its largeness and block hardness. Purposely-designed experimental equipment has been applied for sampling analysis of the rock fracturing in the process of its drilling by means of rotary drilling rig. The abovementioned supported representativeness of the sampling. Findings. Statistical distributions of the rock blockiness structure in terms of each bar length involving its place within the drilling assembly as well as in terms of the well depth have been compiled. Visual comparison of experimental data and theoretical data has helped determine that the statistical distributions of natural blockiness structure of the rock have the closest correlation with gamma distribution which differential function has two positive parameters. Statistical dependence has been defined between drilling-and-blasting results and the total expenditures connected with hard rock mining. Originality. A concept of oversize crushing coefficient has been introduced; its statistical dependence upon the mined rock hardness and specific consumption of the applied explosive has been derived. An alternative has been proposed concerning changes in parameters of the differential function of the assumed gamma distribution relative to the predicted granulometric composition of rock mass. Practical implications. Economic and mathematical model has been developed involving a target function of the total expenditures connected with the listed operations as well as a set of constraints avoiding incorrect decisions. The optimization method makes it possible to control drilling-and-blasting parameters at each stage of hard rock mining.

Purpose. Predicting the stress-strain state (SSS) of the rock mass in the zone of stope operations influence using the selfcaving mining system and the calculation of the load-bearing capacity of mine workings support at the 10th Anniversary of Kazakhstan’s Independence mine. Methods. An engineering-geological data complex of the host rocks properties has been analyzed. Numerical modelling of the rock mass stress-strain state and the calculation of the load-bearing capacity of the support types used at the mine have been performed with the help of the RS2 software. This program, based on the Finite Element Method in a two-dimensional formulation, makes it possible to take into account a significant number of factors influencing the mass state. The Hoek- Brown model with its distinctive advantage of nonlinearity is used as a model for the mass behaviour. Findings. The values of the main stresses and load on the support have been obtained. According to the numerical analysis results of the rock mass stress-strain state at a depth of 900 m (horizon -480 m), the principal stresses are close to hydrostatic ones σ1 = σ3 = σz = 24.8 MPa. Predicting assessment of mine workings stability margin is performed before and after stope operations. Based on its results, it can be assumed that the stability margin of the mine workings driven in the stope zone is below the minimum permissible, therefore, caving and an increase in the load on the support are possible. Abutment pressure on mine workings support at a mining depth of 900 m (-480 m) has been calculated. The parameters of support in mine workings driven at the horizon -480 m have been calculated. Originality. The nature and peculiarities of patterns of the stress-strain state formation within the boundaries of various stope operations influence in blocks 20-28 at the horizon -480 m have been determined. The quantitative assessment of the values of loads on the support of haulage cross-cuts of the horizon mining is given. Practical implications. The research results can be used for creating a geomechanical model of the field and to design stable parameters of mine workings support.

Purpose. To perform research and detailed analysis of the stress deformed state of rocks around the haulage roadway based on the numerical modeling with the purpose to select the rational type and design of the haulage roadway support at the Beskempir field. Methods. A comprehensive research method has been used: review and generalization of references related to the study of the stress deformed state of a rock mass, improvement of the walling technology, in-situ and laboratory tests in the research and testing of rock samples strength; application of mathematical statistics and processing of experimental data using software products. The numerical modeling of the stress deformed state was done using the Examine 2D application with due account for the shape of broken rocks area, which is a 138х138х138 m regular triangle. Barton’s Q-system was used to the RQD assessment. Findings. The numerical modeling of the stress deformed state of rocks in the tectonic fault zone of the haulage roadway at +230 m was performed, and the rock mass deformation zones were defined around the mine contours. The charts showing displacement of roof rocks and walls of the haulage roadway were built, where it was established that the maximum displacement was manifest over the tectonic fault zone. The following zones were identified: the rock mass instability zones, the rock mass instability zones with due account for its fracturing, the zones of stable and unstable rock masses of the haulage roadway. It was established that 41.6% of the working with the fault zone is unstable, and 58% of it is a more stable part. It is proposed to divide the haulage roadway into three sections depending on the rock stability with a certain type of support. Originality. Based on the study of the stress deformed state of the rock mass in the conditions of the Beskempir field, site-specific unstable sections were identified. They ensured the selection of the support design with adjustable resistance. Practical implications. The application of support with adjustable resistance depending on the rock mass stability ensures minimization of costs for roadway support, maintenance of extensive sections of the working as well as enhanced mining safety in specific mining and geological conditions of the Beskempir field.

Purpose. To substantiate changes in stress-strain state of rock mass in the process of long-pillar mining with the help of double-unit longwalls while evaluating stress of a mine field in terms of Lvivvuhillia SE mine. Methods. Analysis of the plans of mine workings has become a basis for the evaluation of physical and geometrical parameters of a support pressure area of the double-unit stopes depending upon mining and geological as well as engineering conditions for n7b coal seam extraction. 3D model of the rock mass has been rendered using SolidWorks 2019 software. The geomechanical model of the rock mass is based upon the specified output data concerning actual operating schedule of 1018 and 1019 double-unit longwalls (numbers of the longwalls are changed as it has been required by the authorities of Lvivvuhillia SE) in terms of n7b seam and support patterns of the development mine workings in Lvivvuhillia SE mine. Each component of the support was modeled as a separate part with the relevant geotech data. Behaviour of the expansion of the rock mass stress-strain state within the selected point has been analyzed by means of sections at the specified plane. Findings. Rendering algorithm of 3D model of rock mass in terms of long-pillar mining of a coal seam using double-unit longwalls has been developed. A geomechanical model of the rock mass has been substantiated depending upon the mining and geological mode of occurrence and engineering parameters of coal mining process. Originality. Nature of the support pressure area formation in front of a stope as well as along the extraction pillar length has been analyzed. It has been identified that if stopes are within one and the same plane, interconnection of their frontal support pressure areas as well as walls of the development workings take place. In this context, adjoining entry acts as the extra destressing technogenic cavity in addition to its proper functions. Practical implications. Output data to make recommendations concerning the efficient mining parameters and methods for rock pressure control have been identified relying upon the analysis of stress-strain state of rock mass in the process of the operation of double-unit longwalls. Visualization of the principles of formation of the stress-strain state of support pressure area and evaluation of the rock mass condition have shown that the maximum reduced stresses reach 70 MPa in terms of 18 m width of the support pressure area.

Purpose is to determine factors of effect of mechanical parameters and geometry of packs, constructed using the undercut rocks in the process of selective coal mining, on the state of geomechanical system within a mine working-stope junction during a computational experiment. Methods. The computational experiments involved finite-element method to simulate three-dimensional analytical area of the geomechanical system. Rock mass was represented by twelve rock layers and a coal seam. In the process of the computations, neighboring rock layers displace freely relative to each other. Stresses and deformations have been calculated within a full-size 300×160×50 m block involving undisturbed rock mass, a stope and two development workings. Mechanical characteristics of packs were simulated using additional analytical calculations. Findings. The calculations of a geomechanical system of a mine working-stope junction have helped determine typical areas of the disturbed rock mass identifying a propagation mechanism of the stope roof fall taking into consideration the effect of backfilling parameters. Analysis of stress-strain state (SSS) of the geomechanical system within the stope roof, using the selected cross-sections, made it possible to define conditions of interaction of the rock layers resulting in the roof lowering on the packs. Originality. The identified regularities of interaction between a stope roof and backfilling components determine optimum conditions to control a stope roof during selective coal mining. It has been substantiated scientifically that consideration of longitudinal horizontal stresses to identify optimum backfilling parameters makes it possible to define unambiguously both a type, and geometry of protection schemes for the mined-out area of a stope in terms of different strength parameters and geometrical parameters of the disturbed rock mass. Practical implications. The results have helped determine a mechanism of a stope advance velocity as well as a type and geometry of the packs being constructed. The abovementioned makes it possible to minimize expenditures for internal logistics; to cheapen prime cost of mining; and to improve safety of stope miners.

Purpose is to analyze nature of rock deformation and to estimate experimentally state of mine workings being supported under the conditions of areas disturbed by coal mining. Methods. The studies involved field instrumental observations within measuring points equipped with contour benchmarks. Express method was applied to determine height and width of the mine working; typical supported areas were designed; and photographs were taken. The research was conducted in a belt roadway and ventilation raise of western longwall 11 (c18 seam of MM “Pivdennodonbaske No. 1”), and in their connections with the longwall. Findings. It has been determined that the longwall effect in the mine working, being supported repeatedly, is 80 – 60 m in front of a stope; vertical convergence within the area is more than 1 m; floor rise share is almost 76%; and share rate is more than 3 mm/day. It has been specified that local destruction of anchor fitting as well as almost 70% of deformation of frame support is observed within the zone of the longwall affect. It has been identified that potential inrush area from the belt roadway is between supports 3 and 9 of a face zone support; i.e. distance from the seam edge is more than 2.4 m. It has been proved that the use of rigid protective structures is not efficient in the context of soft floor rocks since the protective structures function like dies. Condition of the belt roadway, being constructed and supported behind the longwall, is satisfactory; boundary deformations are within the range of the support flexibility. Originality. Regularities concerning deformation of boundaries of mine workings under the conditions of unstable wall rocks of c18 seam (MM “Pivdennodonbaske No. 1”), when the mine workings are being constructed and supported behind a stope to be used repeatedly for following longwall, have been determined. Regularities of the process when rocks are forced out into a mine working cavity remained after protective structure, being constructed along a mine working at the boundary of the worked-out area, have been identified as well as regularities of vertical convergence rocks within terminal sites of the longwall. Practical implications. The findings can be used to develop measures and means for the stability of development mine workings under the conditions of unstable wall rocks and measures to prevent their fall within the tail longwall sites.

Purpose is to substantiate the efficiency of geomechanical model of the mine working on the basis of qualitative and quantitative parameters of stress and strain state of the mine working and to compare the results of computational experiment both with the results obtained while designing mine working support and with the results of field studies under mine conditions. Methods. The studies consisted of three stages. Stage one involved development of the computational model and, using a finite-element method (ANSYS Software Package), and performance of computational experiment for mining and geological conditions of MM “Pokrovske”. Stage two involved field measurements in the mine working with the support pattern developed according to the results of first stage of the research. Characteristic points were selected to determined separate stress and deformation components of a geomechanical system. Stage three dealt with comparative analysis of both computational and field experiments to define the efficiency of the selected computational model and the engineering solutions. Findings. The substantiated physical and mathematical model as well as geometry of computational region of the geomechanical system have made is possible to determine to a high precision stress and strain state of all the components of mine working support and neighbouring rock mass. Analysis of changes in mine working border, while calculating and full-scale measuring, has demonstrated high accuracy degree in description of deformation processes within the rock mass. Qualitative changes in stresses within the selected anchors, in the process of the stope plane movement, correspond in their appearance to the curves of graphs obtained as a result of calculations. Originality. For the first time, complex multicriteria approach has been proposed and applied to determine efficiency of the selected support scheme based on the measurements of mine working border displacement and internal effects of the support components; the approach makes it possible to evaluate adequacy of the selected computational scheme while predicting changes in the geomechanical system state. Practical implications. The developed innovative methodology to prove the efficiency of selecting optimal system for mine working support helps reduce design costs and cut production expenses while mounting and operating the support from a holistic perspective. Validation of the fact that calculated results of stress and strain state of a geomechanical system correspond to the data of field measurements in terms of various stress and deformation criteria provides the possibility of the computational model interpolation with respect to the mine workings driven and designed under similar mining and geological conditions.

Purpose. To develop the technology for explosive destruction of solid inclusions in the mass of rocks with different hardness on the basis of established correlations between changes in the radius of hard streaks fragmenting, fracturing density and relative distance to the free surface during various initiating techniques in rocks of different hardness. Methods. Theoretical and experimental research into the development of scientific and technical fundamentals of explosive destruction of the mass of rocks with different hardness, which allows to determine the zone of hardening soft rocks located between solid inclusions. Findings. The developed technology for explosive destruction of mass of rocks with different hardness was implemented in the Tashkura quarry of Dzheroj-Sardara phosphate deposit of Navoiy MMC resulting in the economic effect of UZS 581.7 mln per 10.5 mln m3 of the extracted rock, while the economic effect in the free industrial and economic zone “Navoiy” was more than UZS 12 mln per 17000 m3 of the extracted rock. Originality. The conducted complex research resulted in the new technology for explosive destruction of the mass of rocks with different hardness, including hole boring, determination of the number and capacity of hard streaks in the process of boring, placing of the explosive charge in the hole, stemming. and blasting. Practical implications. Implementing the research results in the open quarry of Navoiy MMC allowed to make a significant contribution to the solution of the topical scientific and practical problem: efficient blast energy utilization during industrial explosions on hard streaks.