Vertical Mine Shaft Research Articles

Numerical Modeling the Rock Mass Stress-Strain State Near Vertical Excavations in Combined Mining

In recent years, the development of the mining industry in the Republic of Kazakhstan has been accompanied by the commissioning of new underground levels for many existing mineral deposits, which were initially developed through open-pit mining. As the depth of open-pit mining increases, the volume of overburden rises sharply, making open-pit mining unprofitable due to the significant amount of additional mining work required. For this reason, most open-pit mines in Kazakhstan are transitioning to underground mining, or combined mining. Many researchers have examined the timing of this transition and have worked on optimizing it to determine the best economic efficiency and manage risks. However, there is limited information available on how to determine the optimal location for a vertical mine shaft when transitioning from open-pit to underground mining. The purpose of this study is to identify a safe location for a vertical shaft in combined mining operations. Specifically, the study assesses the impact of the open-pit mine on the selection of the mine shaft’s location, considering the stress-strain state of the rock mass during combined mining methods. To address these objectives, numerical modeling of the stress-strain state around vertical excavations during combined mining was performed. The results provide a solution to the critical issue of determining the location of the mine shaft in combined geotechnology and lay the groundwork for further research on shaft placement in Kazakhstan. The novelty of this study lies in identifying the shaft location by considering the geometric shape of the open-pit mine and the depth of development. Doi: 10.28991/CEJ-2024-010-09-010 Full Text: PDF

Risk-forming areas of mine hoisting equipment and directions for reducing contact loads on shaft reinforcement

The paper considers the influence of diagram of peripheral rotational speed of the rope-driving body (pulley, drum) of a mine hoist on dynamic processes in the system “hoisting vessel - reinforcement” of a vertical mine shaft. It is shown that areas of abrupt speed changes (acceleration or deceleration, override in case of smooth motion disturbances, accidental rubbing, vessel catching on ledges in the guides, etc.) create a peripheral acceleration or deceleration of the pulley or drum rims, which causes longitudinal excitation of the upper ends of the main ropes. These and other factors lead to a sharp increase in the contact loads of shaft guides and braces, and an increased risk of their sudden failure, especially when the safety margins are reduced due to significant wear and tear of metal structures. The ways to adjust and optimize the actual hoisting speed diagram in order to reduce the contact loads on the shaft reinforcement and the associated risks of accidental hazards of mine hoisting equipment (MHE) are determined.

New solutions for mechanized small diameter shaft sinking for residual oil production

The huge losses of oil in the subsurface necessitated the search for ways to extract residual oil, which led to the idea of combined use of the practice of mining and oil production. This involves drilling two vertical wellbores in the side rocks on the lying side of the oil reservoir, which are connected by two inter-hole joints. From the upper joint, a full series of wells pass along the entire strike of the formation at a certain interval with depth into the formation, into which steam supply pipes are placed with plugged ends at the bottom of the wells and lateral dispersed holes along their entire length. At the wellhead, these pipes are connected to individual high-pressure pulsating electric steam generators, and the wells themselves at the wellhead and the steam supply pipes are plugged. The electric steam generators are operated in line with a preset program. The most labor-intensive and costly in the idea of combined use of mining and oil production technologies is the sinking of vertical mine shafts, which requires new solutions in mine development technologies. In this regard, it is planned to reduce the cost of mining operations with the purpose of their use in oil production by means of non-explosive continuous mechanical-hydraulic pulse breaking of rocks of any strength and abrasiveness. Keywords: hydraulic pulse breaking of rocks; residual oil recovery technology; minimum diameter shaft sinking; two-jaw grab.

ПРОМЫШЛЕННЫЕ ОТХОДЫ ДЛЯ ЗАКЛАДКИ ВЫРАБОТАННЫХ ПРОСТРАНСТВ УГОЛЬНЫХ И РУДНЫХ ШАХТ КУЗБАССА

Coal mining and mining enterprises are the basis of the Kemerovo region economy. Comprehensive assessment of their impact on the environment showed the activation of exogenous geological processes: dips formed over previously liquidated inclined and vertical mine shafts; waterlogging; drawdowns and landslides. In the flooded goaf spaces of mines the structure of rocks is disturbed, the fixing material of the workings is destroyed, forming dips and subsidence troughs. Traditional goaf backfilling technologies using cement, sand and gravel make products more expensive, what makes coal mining and mining enterprises in the region unprofitable. A significant reduction in the cost of backfilling is possible with the introduction of industrial waste disposal technologies - using them as components of hardening mixtures in the development of coal and ore deposits. Taking into account the mining and geological conditions of Kuzbass - powerful steep and inclined deposits, compositions of cement-free laying mixtures with the use of steel slags for the industrial implementation of chamber and floor-chamber development system were developed. Key words: stowing mixtures, steel slag, strength, structure, burnt rock, sludge.

Prediction of the state of the ice-bearing massif during the penetration of a vertical mine shaft with freezing

Te subject and purpose of the work. Te article is devoted to the problem of sinking shafs traversed by the method of artifcial freezing of shafs at the stage of elimination of ice and rock fencing. Te relevance of the study is explained by the increased requirements for the reliability of the process during the tamponage of the fxed space of the trunks and during the operation of the trunks for an indefnite time. Te novelty of the article consists in the development of the parameters of the technology that eliminates the uneven load on the tubing support during the expansion of the inner ring layer during artifcial thawing by pumping hot brine into freezing columns. Te methodology of the work includes a complex of studies: analysis of literary sources, theoretical and feld studies, modeling of processes and experimental verifcation of the data obtained. Te results of the work. It was revealed that the stresses in the support lead to the separation of concrete from the tubing column and the formation of water-flled cavities. It is established that forced thawing of the array by pumping hot brine into freezing columns causes uneven loads on the tubing support and threatens with an accident. It is determined that the most acceptable option is thawing by feeding warm air into the barrel and circulating a coolant with an optimal temperature. Use of results. Te technology can be in demand in the construction of capital mining facilities in particularly unfavorable conditions. Conclusions. Te most favorable mode of artifcial thawing is created when heated air is fed into the barrel and the coolant into the columns with an increase in the coolant temperature smoothly while maintaining the required level.

Analysis of the stress-strain state of problematic sections of the shaft of the mine using computer simulation

The article presents the computer simulation results for the stress-strain state of the lining sections of the shaft No. 1 of mine 3 of JSC Belaruskali that were obtained using visual and instrumental investigation of the mine lining state. The loading parameters of the shaft take into account the specific feature of the lateral pressure calculation in the considered location. This means that the shaft intersects vertically rocks different in their physical and mechanical properties. Computer simulation of loading of the most problematic vertical mine shaft sections observed by the lining examination results was performed using the Static Structural component of the ANSYS Workbench engineering software package. Distribution diagrams of longitudinal normal, shear and von Mises equivalent stresses in the vertical mine shaft lining are obtained for the design and residual values of the cast-iron tubing thickness. A comparative analysis of the mine shaft residual bearing capacity for various parameters of the lining elements was carried out. Based on the computer simulation results, the conclusions were made on the bearing capacity of the shaft No. 1 of mine 3 of JSC Belaruskali and the recommendations for a further safe operation of the mine shaft were suggested.

ПЕРСПЕКТИВИ ВИКОРИСТАННЯ НОВІТНІХ ТЕХНОЛОГІЙ СПОРУДЖЕННЯ СТВОЛІВ ТА СВЕРДЛОВИН ДЛЯ ПОВОЄННОЇ РОЗБУДОВИ ВУГІЛЬНОЇ ГАЛУЗІ УКРАЇНИ

Purpose Analysis of production experience, scientific and technical developments and assessment of prospects for the use and development of the latest technologies for the construction of vertical mine shafts and wells for the post-war development of the coal industry of Ukraine. Methods. The methods of analysis of the accumulated production experience of drilling shafts and wells, first, in the leading mining countries and in Ukraine, as well as scientific and technical literature, were use. Findings. The classification of technologies of vertical shafts and wells construction methods was consider. It’s tested and promising ones for Ukraine were analyze, in relation to the restoration and creation of mining capacities, technological schemes and equipment for the construction of vertical openings mainly with mechanical destruction of rocks in the hole, the production experience of the Donetskshakhtoprokhodka and Spetsshakhtoburinnia trusts was summarize. from the point of view of use, in particular, during the construction of new coal blocks of PJSC «Mining Management «Pokrovske», large-scale investment projects. The possibility of using a modified parallel technological scheme for traditional blasting technology is substantiate. The prospects of mechanized boring of shafts in Ukraine – by drilling and with the use of shaft boring combines of leading world manufacturers – were evaluate. These opportunities can be realize in case of acceptance and implementation by Ukraine's partners of a modern analogue of the "Marshall Plan" after the victory over the aggressor. Originality. The results of the analysis of technological schemes and methods of drilling vertical shafts and wells, the accumulated production experience and scientific and technical developments are summarize, the trends and prospects of the development of mine construction technologies – the driver of the development of the national mining industry – are considered. Practical implication. The analysis of technological schemes and methods of drilling vertical shafts and wells was perform based on domestic and foreign production experience. Key words: vertical shaft, borehole, sinking technology, mechanical fracture, rodless boring, shaft-borehole machine, pilot borehole.

THM-coupled numerical analysis of temperature and groundwater level in-situ measurements in artificial ground freezing

Belarusian Potash salt deposits are bedded under aquifers and unstable soil stratums. Therefore, to develop the deposits a vertical mine shaft sinking is performed using the artificial ground freezing technology. Nowadays, real time observations of ground temperature and groundwater level is applied to control the ground freezing process. Numerical simulation can be used for a comprehensive analysis of measurements results. In this paper a thermo-hydro-mechanical model of freezing of water saturated soil is proposed. The governing equations of the model are based on balance laws for mass, energy and momentum for a fully saturated porous media. Clausius-Clayperon equation and poroelastic constitutive relations are adopted for description of a coupled change in water and ice pore pressure, porosity and a stress-strain state of freezing soil. The proposed model enables us to describe evolution of equivalent water content measured in Mizoguchi’s test and predict frost heave strain in one-sided freezing test. Numerical simulation of ground freezing in the Petrikov mining complex located in Belarus has shown that the model is able to describe field measurements of pore pressure inside a forming frozen wall. Furthermore, the mismatch between hydro- and thermo-monitoring data obtained during the artificial freezing is analyzed.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ ПРОХОДКИ ГОРНЫХ ВЫРАБОТОК ПО СВЕРХПРОЧНЫМ ПОРОДАМ

The article provides a justification for the use of the technology of mechanized sinking of vertical mine shafts. Conclusions are drawn about the rational technological parameters of the destruction of the slaughter breast by a combined mechanical method. It is concluded that it is necessary to conduct additional experimental studies to clarify the physical constants of the rock and to apply alternative destruction criteria.

Variable actual stiffness of guides in potash mine shafts

The article addresses serviceability of reinforcement in vertical mine shafts. The mathematical framework is presented for the dynamic processes in the capsule–reinforcement system. The main causes of the dynamic loads in the capsule–reinforcement system are discussed. The importance of the processes in the capsule–reinforcement system during movement of hoists in vertical mine shafts is emphasized. It is asserted that solely computational methods are not enough to analyze processes inside the capsule–reinforcement systems in shafts. It is required to examine actual parameters of shaft reinforcement, in particular, the actual stiffness of shaft guides. The actual measurement procedure of guide stiffness in potash mine shafts is presented. The full-scale tests data are set out in connection with the actual step of reinforcement in shafts. The actual and calculated values of stiffness of shaft guides are compared. Based on the obtained results, the variable stiffness coefficient is derived for the shaft guide stiffness for a few alternative of reinforcement step. Considering the described research findings and the many years-long experience gained in operation of mine shafts, the authors have drawn a conclusion on the necessity to take into account the factor of variable stiffness of guides in shaft design and construction in potash mines in the Upper Kama Potash–Magnesium Salt Deposit, especially in case when the shaft reinforcement step exceeds the project design standards.

Construction and operation of batching plants in difficult geological conditions of Upper Kama potash mines

Scenarios of the component arrangement of batching plants in the system of a vertical mine shaft are discussed. The features of operation of batching plants in vertical shafts of potash mines are identified. The actual recorded damages generated in the lining of batching plants in the course of their longterm operation in potash mines are described. The geomechanical researches aimed to determine vertical convergence in batching rooms of mine shafts, as well as for monitoring of crack opening and displacements in sidewalls in the batching chambers are presented. The major results of the full-scale geomechanical observations are reported, and the main causes of fractures in concrete and reinforced concrete lining at junctures of shafts and batching rooms and shaft bins are identified. The set of the engineering solutions implemented for the protection of lining in batching facilities during construction of mine shafts is described, and its efficiency is evaluated. The mathematical modeling is carried out to estimate various negative impacts on deformation and fracture of concrete lining in shafts with regard to the time factor. From the modeling results, the dominant cause of concrete lining damage in batching chambers and in mine shaft is found. Based on the accomplished research results and actual long-term experience of operation of mine shafts, the most favorable factors are determined for the best design choices in construction and long-term maintenance-free operation of batching plants in potash mines of the Upper Kama Potash–Magnesium Salt Deposit.

Theoretical study of partially return air flows in vertical mine shafts

This paper is concerned with a theoretical study of the conditions for occurrence of partially return air flows in vertical mine shafts. Such problem arises when the temperature of the air rising in the vertical mine shaft is much higher than the temperature of the shaft walls. This situation can occur during the construction of mine shafts using artificial freezing of surrounding rocks. The uncontrolled return air flows in the shaft under construction may cause an accumulation of harmful impurities released during drilling and blasting operations and a deterioration of microclimate parameters in the atmosphere of mine shafts. We investigate here a two-dimensional, fully turbulent, unsteady air flow in a vertical domain. In accordance with the Boussinesq approximation, the air density is specified as a function of temperature. The results of simulations show that a significant change in the transverse air velocity profile and the occurrence of return air flows are observed at Rayleigh numbers (dimensionless temperature difference) of order of 109. We propose two criteria for quantitative analysis of the flow structure: the critical Rayleigh number which denotes the occurrence of return flows in the cross section of the shaft and the transforming Rayleigh number which serves as indicator of significant changes in the velocity profile. Numerical dependences of the critical and transforming Rayleigh numbers on the Reynolds number of the airflow in the shaft are determined.

Geomechanical characteristic of ventilation shaft VS-3 in Oktyabrsky mine during extraction of mineral reserves from protective pillar

The strain analysis procedure is discussed in terms of a vertical mine shaft under the impact of extraction of ore reserves from protective pillar in Oktyabrsky mine of NorNickel’s Polar Division. The procedure is used in predictive strain analysis in depth of the shaft in case of different scenarios of protective pillar mining in ventilation shaft No. 3. The calculations show impossibility of preservation of shaft VS-3. Based on the prediction, it was decided on the early analysis of ventilation alternatives in the mine without involvement of shaft VS-3. The implemented research saved significant assets from spending on the shaft maintenance in the period of extraction of ore reserves from the protective pillar. Moreover, the time allowance until disability of shaft VS-3 enables scheduled planning and construction of access gateways to ensure the required ventilation mode in the mine. The authors appreciate participation of D. A. Kotikov, S. Yu. Shilenko, V. V. Balandin, M. P. Sergunin, A. V. Kulov, V. N. Andreev and A. K. Ustinov in the study.

Development of the Ice Wall during the Construction of Vertical Mine Shafts

The issue of creating and maintaining an ice wall (ICW) for mine shafts is considering in this article. The relevance of the study is due to the growing demand for such minerals as, for example, potash ore. Such ore is mined by the mine method, in which ICW is used to ensure the strength and waterproofing of the shaft. The main problem lies in the correct calculation of the required thickness of the ICW and cooling capacity, the choice of modes and freeze mechanism. The choice of different solutions affects capital and operating costs. The task is to assess the influence of the freezing pipe layout and the selected coolant temperature on the cost of capital and operating costs. Also, the analysis of the influence of the above factors on the process of soil freezing itself was carried out. Analytical methods of calculation and special software were used for the study. The reasons were considered that did not allow creating a closed ice wall, since they are often caused not by the choice of a circuit design and temperature regime, but by a violation of the drilling technology and installation of pipes. As a result, this article brings together the experience of creating an ice wall and provides a comparative analysis of various solutions.

Numerical simulation of cement grouting of saturated soil during a mine shaft sinking using the artificial ground freezing

Cement grouting is widely applied in geotechnical engineering to reinforce water saturated soil and to control groundwater. The present paper is devoted to a numerical study of cement grout injection in a soil stratum during a construction of a vertical mine shaft using the artificial ground freezing (AGF) technology. For the study a thermo-hydro-mechanical model was developed. The governing equations of the model are derived based on the theory of porous media. The model takes into account the features of AGF and grouting processes such as a non-Newtonian behavior of cement grout flow, water-ice phase change and an influence of pore pressure and temperature on an evolution of a stress-strain of the soil. Three-dimensional numerical simulation of cement grouting of unfrozen soil between the shaft lining and the ice-soil wall was conducted using the model for various injection regimes. Results of the simulation have shown that the grout injection leads to a rise in temperature and volumetric strain in the soil. A mechanical impact of the injection procedure on the shaft lining is an increase in the mechanical pressure near the injection boreholes and a redistribution of the von Mises stress.

Evaluation on the Stability of Vertical Mine Shafts below Thick Loose Strata Based on the Comprehensive Weight Method and a Fuzzy Matter-Element Analysis Model

Damage to mine shafts located below thick loose aquifers, caused by coal seam mining, can seriously affect the operational safety of mines. In view of such a problem, the comprehensive weight method and the fuzzy matter-element analysis method were used to analyze and evaluate the stability of mine shafts below thick, loose aquifers. Based on data relating to shaft structure parameters collected from fifteen damaged shafts in coal mines in East China, a comprehensive analysis was performed. The results showed that (1) the two indexes of surface subsidence velocity and water level drop value at the bottom of a loose aquifer have a large influence on the stability of shafts below thick loose aquifers, and (2) the predicted results of thirteen sets of samples were the same as the results measured during actual production; the accuracy of the model was 86.67%. The comprehensive weight method and the fuzzy matter-element analysis model both show good reliability for evaluating the stability of mine shafts below thick loose aquifers and can provide a scientific reference for the analysis of the stability of mine shafts in areas with thick loose strata, as well as for the design of comprehensive control plans that could subsequently be implemented.

Technology of performance of ice wall when sinking shafts at the example of the objects of the Petrikov mining

Scientific-technical aspects of technology of use of the ice wall when shaft sinking in water-bearing rocks, using an example of objects under construction of the Petrikov mining and processing plant, are studied. The algorithm of process of freezing of the mountain massif is described. The method is developed of calculation of the main parameters of the ice barrier, based on classical scientific concepts in the field of geotechnology, geomechanics and mountain thermal physics, containing modified formulas of thickness and time of the ice wall formation. The high efficiency of the developed technique is confirmed by the results of the successful use of the obtained numerical values of the parameters of the fence in the implementation of the project of sinking shafts. It is shown the possibility of choosing a method of defrosting frozen rocks, based on the analysis of a real three-dimensional model of the ice barrier. The most important criterion for this choice is the uniformity of the thickness of the ice barrier along the circumference of the vertical cylinder. The conclusion is made about the high scientific and practical competence of Belarusian mine builders – scientists and specialists. The country has developed a reliable system of scientific and technical support for the technology of sinking vertical mine shafts using temporary ice fences. Effective methods of preliminary geological studies, calculation of parameters of ice-rock fences and freezing equipment, selection of technology of work have been created. The necessary material and technical base for fast and high-quality performance of all complex of works on a construction of mine trunks in the special way is created.

Numerical simulation of soil stability during artificial freezing

Artificial ground freezing is an efficient method for construction of vertical mine shafts under hard geological and hydrological conditions. The present article is devoted to a numerical simulation of mechanical behavior of soils surrounding freezing wells during a shaft sinking with a use of the artificial ground freezing method. The numerical simulation is carried out on the basis of a thermo-hydro-mechanical model of freezing process in a water saturated rock mass. Constitutive relations are derived within framework of thermo-poromechanics in consideration of the phase transition. Description of the mechanical behavior of soils is performed in the elasto-plastic formulation. The model allows one to take into consideration an influence of frost heave and temperature change on strain of soils under freezing process. Plastic strain is estimated with a use Drucker-Prager criterion. The numerical simulation of artificial freezing of a rock mass has been carried out for two cases. In the first case a response of soils adjacent to freezing wells on an application of the AGF method and a shaft sinking has been analyzed. In the second case stress-strain state in a neighborhood of the freezing well has been determined. It has been shown that the artificial freezing and excavation works leads to an increase of mechanical pressure in near-wellbore domains. Frost heave and temperature deformation induced by the artificial freezing cause displacement of soil in the vertical and horizontal directions.

Study of the Dynamic Loading Impact on the Design of Pentices when Sinking Vertical Mine Shafts

Based on the reconstruction project for Gorno-Shorsky branch of JSC “Evrazruda” developed by JSC “Giproruda” to maintain the enterprise’s production capacity of 6 million tons per year, the shaft “Skipovoy” should be sunk from the level of 115 m to the level of 85 m. Due to the fact that the reconstruction period was to be shortened, the employees of LLC “SibGorComplex Engineering” together with the Underground and Mine Construction Department of T.F. Gorbachev Kuzbass State Technical University developed several variants of new design of wedge pentices for vertical mine shaft sinking under hoisting operations. The results of studies of the dynamic loading impact on the design of safety devices in skip shaft sinking are presented in the article. Based on the method of designing the force action essentials for the emergency skip dumping, the functions allowing determining the value of the impact on the main structural elements of pentices completely bridging over the shaft cross-section that can be used to substantiate the design parameters of new wedge pentices.

Creep behavior of ice-soil retaining structure during shaft sinking

The article is devoted to analysis of deformation of an ice-soil retaining structure during a vertical mine shaft sinking by applying the artificial ground freezing technique. The analysis was performed by finite element numerical simulation. Since frozen soils possess rheological properties, creep deformation of the ice-soil structure was considered. To determine the creep deformation, the Vaylov’s constitutive relations was used. In the relations the creep behavior is described by the Norton-Bailey creep law and the volumetric creep strain is restricted to be zero. The wall thickness of the ice-soil structure was estimated by the Vaylov’s formula that is widely used in structural design of potash mines. As a result of the study, it was established that for time required for the lining installation at large depths of the shaft sinking the creep deformation of the ice-soil structure exceeds admissible value guaranteeing safety of the excavation process.