scholarly journals State and prospects for the development of thick-seam mining technology in the southern Kuzbass

2021 ◽  
Vol 330 ◽  
pp. 01011
Author(s):  
Anastasia Vargolskikh
Keyword(s):  
Statistical Analysis ◽  
Coal Production ◽  
Coal Seams ◽  
Thick Seam ◽  
Rational Control ◽  
Coal Pillars ◽  
The Stability ◽  
Seam Mining ◽  
Roof Rocks ◽  
Shape And Size

The paper discusses the factors that limit the growth of coal production in Kuzbass. They were identified by the results of statistical analysis of the actual production indicators of working faces in eight thick coal seams. Technological solutions for the rational control of hard-to-break roof rocks, the shape and size of coal pillars, which ensure the stability of protected workings and isolation of the worked-out area from endogenous fires, are substantiated.

scholarly journals Failure Mechanism and Control Technology of Thick and Soft Coal Fully Mechanized Caving Roadway under Double Gobs in Close Coal Seams

2020 ◽  
Vol 2020 ◽  
pp. 1-23
Author(s):  
Shengrong Xie ◽  
Xiaoyu Wu ◽  
Dongdong Chen ◽  
Yaohui Sun ◽  
En Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Field Distribution ◽  
Control Technology ◽  
Coal Seams ◽  
Anchor Bolt ◽  
Anchor Cable ◽  
Coal Pillars ◽  
Seam Mining ◽  
And Control

The surrounding rock of the roadway under double gobs in the lower coal seams is partially damaged by the mining of the upper coal seam and the stress superimposition of the stepped coal pillars. What is worse, the upper layer of the roof is collapse gangue in double gobs, which makes the anchor cable unable to anchor the reliable bearing layer, so the anchoring performance is weakened. The actual drawing forces of the anchor bolt and anchor cable are only approximately 50 kN and 80 kN, respectively. The roadway develops cracks and large deformations with increasing difficulty in achieving safe ventilation. In view of the above problems, taking the close coal seam mining in the Zhengwen Coal Mine as the engineering background, a theoretical calculation is used to obtain the loading of the step coal pillars and the slip line field distribution of the floor depth. The numerical simulation monitors the stress superimposition of stepped coal pillars and the distribution of elastoplastic areas to effectively evaluate the layout of mining roadways. The numerical simulation also analyzes the effective prestress field distribution of the broken roof and grouting roof anchor cable. A laboratory test was used to monitor the strength of the grouting test block of the broken coal body. Then, we proposed that grouting anchor cable be used to strengthen the weak surface of the roof and block the roof cracks. From on-site measurement, the roadway was seen to be arranged in the lateral stress stabilization area of the stepped coal pillars, the combined support technology of the grouting anchor cable (bolt) + U type steel + a single prop was adopted, the roadway deformation was small, the gas influx was reduced, and the drawing force of the anchor bolt and the anchor cable was increased to approximately 160 kN and 350 kN, respectively. The overall design and control technology of the roadway can meet the site safety and efficient production requirements.

scholarly journals A COMPREHENSIVE STUDY OF THE STABILITY OF LATERAL ROCKS WITH A SUPPLE SUPPORT

World Science ◽  
2020 ◽  
Vol 1 (1(53)) ◽  
pp. 4-17 ◽  
Author(s):  
Iordanov I. V. ◽  
Simonova Yu. I. ◽  
Polozhy A. V. ◽  
Podkopayev Ye. S. ◽  
Skyrda A. Ye. ◽  
...  
Keyword(s):  
Strain State ◽  
Laboratory Experiments ◽  
Flexible Structures ◽  
Crushed Rock ◽  
Beam Model ◽  
Coal Pillars ◽  
The Stability ◽  
Stratified Rock ◽  
Roof Rocks ◽  
Comprehensive Study

A complex of analytical studies of the stability of lateral rocks with a supple support, where the coal seam roof was a beam model, some laboratory experiments on samples made from optical and equivalent materials, as well as some mine experiments were was carried out. As a result of the studies, it was found that the stability of lateral rocks with a supple support of crushed rock depended on the compaction of the backfill array on which the roof rocks were based. It was experimentally proved that with external force, the coefficient of compaction of the backfill array changes according to the hyperbolic dependence, the maximum values of which were determined as a result of compaction of the supple support consisting of heterogeneous fractions of the starting material of a certain bulk density. The change in the stress-strain state of the lateral rocks in the coal array with a roadway depended on the bending stiffness of the stratified rock mass and the parameters of flexible structures used to support the roadway. When supporting the roadways with supple support structures, the convergence of the lateral rocks on the contour of the stoop roadway was observed exponentially until the support was completely compressed, while supporting the roadways with coal pillars, the displacement of the rocks on the contour of the roadway increased having linear dependence due to the destruction of the pillar. The stability of the lateral rocks, which determines the operational state of the excavation roadways, was ensured by the use of supple supports or stowing the mined-out space, taking into account the reasonable granulometric content of crushed rock, which ensured the maximum values of the compaction coefficient of the backfill array when the roof and coal seat got deformed.

scholarly journals Modeling the Spatial and Temporal Evolution of Stress during Multiworking Face Mining in Close Distance Coal Seams

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yong Zhang ◽  
Jinkun Yang ◽  
Jiaxuan Zhang ◽  
Xiaoming Sun ◽  
Chen Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Temporal Evolution ◽  
Coal Pillar ◽  
Coal Seams ◽  
Geological Conditions ◽  
Coal Pillars ◽  
The Stability ◽  
Close Distance ◽  
Close Distance Coal Seams

Mining in close distance coal seams (CDCSs) is frequently associated with engineering disasters because of the complicated nature of stress distribution within CDCSs. In order to establish a layout of a roadway to minimize the occurrence of disasters associated with mining CDCS, here the spatial and temporal evolution of stress distribution during the multiworking face mining of a CDCS was explored through numerical simulation based on the engineering and geological conditions of the Nantun Coal Mine. The numerical simulation results indicate that, after the extraction of adjacent multiple working faces, the spatial distribution of stress can be characterized with areas of increased, reduced, and intact stress. The superposed stress of inclined seams that are very close to each other propagates through coal pillars in the bottom floor, and this propagation follows neither the line along the axis of the coal pillar nor the line perpendicular to the direction of the floor. It instead propagates along a line angled with the axis of the coal pillar. The roadway can be arranged in the area with reduced stress, to improve its the stability. Based on the computed spatial and temporal evolution of stress, an optimized layout of roadway was proposed. This layout features a reasonable interval between the mining roadway and a minimal proportion of increased stress areas along the mining roadway and is aligned with geological structures.

scholarly journals Investigation of the Optimal Layout of the Roadway in Closely Spaced Ultra-Thick Coal Seams Mining with Remaining Coal Pillars

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Bin Zhao ◽  
Le Gao ◽  
Xianghui Tian ◽  
Yingyu Sun
Keyword(s):  
Stress Reduction ◽  
Site Investigation ◽  
High Water ◽  
High Water Content ◽  
Thick Coal Seam ◽  
Working Face ◽  
Mining Safety ◽  
Coal Pillars ◽  
The Stability ◽  
Seam Mining

The reasonable layout of the roadway in closely spaced, ultra-thick coal seam mining is of great significance to mining safety. Based on the research background of repeated roof leaks in the process of repairing the return air roadway in working face No. 30503 in the Tashan Coal Mine, theoretical analysis, in situ engineering testing, and numerical simulation were jointly adopted to evaluate the stability of the return air roadway under two schemes of repairing the original return air roadway and excavating a new return air roadway. The results show that the vertical mining-induced fissure above the roadway will cause severe damage to the roadway due to the influence of working-face mining when restoration of the roadway excavation is adopted. When choosing to excavate a new return air roadway, the new return air roadway just staggers the vertical cracks located in the top slab of the original return air roadway, putting the roadway in a state of stress reduction, making the roadway itself more stable and conducive to support. Therefore, the new air return tunnel was selected to establish the working face. To ensure safety of the working face during the mining of the original return air roadway, the original return air roadway was filled with high water content materials. Site investigation data show that this material plays a cushioning role in the filling section of the original return air roadway during the mining of the 30503 working face, and the deformation of the new return air roadway during the filling section crossing the original return roadway is stable and well controlled.

scholarly journals Problems of mining the prospective coal-bearing areas in Donbas

2019 ◽  
Vol 123 ◽  
pp. 01011 ◽  
Author(s):  
Serhii Nehrii ◽  
Tetiana Nehrii ◽  
Leonid Bachurin ◽  
Hanna Piskurska
Keyword(s):  
Compressive Strength ◽  
Energy Security ◽  
Coal Seams ◽  
Plastic Deformations ◽  
Advanced Technologies ◽  
Secondary Support ◽  
The Stability ◽  
Technical Solutions ◽  
Roof Rocks ◽  
Mine Roadways

The prospective coal-bearing areas of Donbas in Ukraine have been identified. Their development will increase the energy security of Ukraine. It has been suggested that the development of these areas will involve mining the coal seams in a weak roof and floor environment, which are characterized by low compressive strength, lower density and a tendency to plastic deformations. The stability has been assessed of the rocks outcrop on the contour of mine roadways for mines operating in these areas. It has been determined that roof rocks in most of these mines belong to a range of groups from very unstable to moderately stable, and the bottom rocks are, in most cases, prone to swelling. This complicates the intensive prospective areas mining with the use of advanced technologies, as well as secondary support for retained goaf-side gateroads with limited yielding property. The mines have been determined, for which this issue is relevant when mining the seams with further increase in the depth. The mechanism of displacement in the secondary supports and has been exemplified and studied using the numerical method. The obtained results allowed us to substantiate the necessity of developing new technical solutions for the protection of gateroads under conditions of prospective Donbas areas.

scholarly journals A protective seam mining method by cutting roof with chainsaw arm machine

2020 ◽  
Author(s):  
Tiejun Kuang ◽  
Yang Tai ◽  
Bingjie Huo ◽  
Binwei Xia ◽  
Yanqun Zhang ◽  
...  
Keyword(s):  
Lower Layer ◽  
Mining Method ◽  
Coal Seams ◽  
Working Face ◽  
Protective Seam ◽  
Mining Pressure ◽  
Coal Pillars ◽  
Residual Coal ◽  
Seam Mining ◽  
Protective Seam Mining

Abstract Multiple-layered coal seams widely exist in main coal mining areas of China. When these coal seams are exploited, the pillar mining method is always employed. This leads to many coal pillars left in the upper coal seams as a protective barrier. As a result, these residual pillars will not only cause the loss of coal resources but also could trigger environmental issues and a serious of mine disasters. A theoretical model was built to analyse the effect of the residual pillars. From the theoretical model, it was found that four stress concentration areas were formed by the upper residual coal pillars. To address the issues of the residual coal pillars, Datong Coal Mine Group has developed an innovative technology of the roof cutting with a chainsaw. A new protective coal seam mining method using chainsaw roof-cutting technology is introduced. A numerical model is constructed to analyse the mining pressure distribution law in working face within the lower layer coal seam. From the numerical simulation, the new protective layer mining method could reduce about 15.2% of the advancing stress, which contributes a lot to controlling the mining pressure within the lower layer. The field measurement showed that the hydraulic support utilised at the site was at lower pressure levels, which proves the new protective seam mining method can significantly reduce the working face pressure.

Study on the Collapse Mechanism of the Hard Roof Rocks

2012 ◽  
Vol 524-527 ◽  
pp. 722-725
Author(s):  
Qing Guo Huang ◽  
Feng Gao ◽  
Jun Zhao
Keyword(s):  
Bearing Capacity ◽  
Structural Mechanics ◽  
Collapse Mechanism ◽  
Domino Effect ◽  
Coal Seams ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Hard Roof ◽  
Coal Pillars ◽  
Roof Rocks

The collapse of the hard roof rocks was characterized by its sudden and entire breakage and falling during the mining of the shallow-thick coal seams in Datong district. In this paper, structural mechanics methods was used to study the collapse mechanism of the hard roof rocks. The results showed that when some of the coal pillars lost their load bearing capacity, the pressure of the surronding rocks would be transferred to the left ones which were also to be damaged due to the extra load, and this would cause a domino effect of the adjacent pillars’s failure, and eventually cause the entire collapse of the hard roof rocks.

SUBSTANTIATION FOR SIMPLIFICATION OF CALCULATION MODELS FOR ASSESSMENT OF THE STABILITY OF ROOF ROCKS

2021 ◽  
pp. 25-36
Author(s):  
Oleksandr Ahafonov ◽  
◽  
Daria Chepiga ◽  
Anton Polozhiy ◽  
Iryna Bessarab ◽  
...  
Keyword(s):  
Differential Equations ◽  
Coal Seam ◽  
Cross Section ◽  
Three Dimensional ◽  
Theory Of Elasticity ◽  
Unit Width ◽  
Distributed Load ◽  
The Stability ◽  
Roof Rocks ◽  
Calculation Models

Purpose. Substantiation of expediency and admissibility of use of the simplified calculation models of a coal seam roof for an estimation of its stability under the action of external loadings. Methods. To achieve this purpose, the studies have been performed using the basic principles of the theory of elasticity and bending of plates, in which the coal seam roof is represented as a model of a rectangular plate or a beam with a symmetrical cross-section with different support conditions. Results. To substantiate and select methods for studying the bending deformations of the roof in the coal massif containing the maingates, the three-dimensional base plate model and the beam model are compared, taking into account the kinematic boundary conditions and the influence of external distributed load. Using the theory of plate bending, the equations for determining the deflections of the coal seam roof in three-dimensional basic models under certain assumptions have a large dimension. After the conditional division of the plate into beams of unit width and symmetrical section, when describing the normal deflections of the middle surface of the studied models, the transition from the partial derivative equation to the usual differential equations is carried out. In this case, the studies of bending deformations of roof rocks are reduced to solving a flat problem in the cross-section of the beam. A comparison of solutions obtained by the methods of the three-dimensional theory of elasticity and strength of materials was performed. For a beam with a symmetrical section, the deflection lies in a plane whose angle of inclination coincides with the direction of the applied load. The calculations did not take into account the difference between the intensity of the surface load applied to the beam. Differences in determining the magnitude of the deflections of the roof in the model of the plate concerning the model of the beam reach 5%, which is acceptable for mining problems. Scientific novelty. To study the bending deformations and determine the magnitude of the roof deflection in models under external uniform distributed load, placed within the simulated plate, a strip of unit width was selected, which has a symmetrical cross-section and is a characteristic component of the plate structure and it is considered as a separate load-bearing element with supports, the cross-sections of this element is remained flat when bending. The deflection of such a linear element is described by the differential equations of the bent axis of the beam without taking into account the integral stiffness of the model, and the vector of its complete displacement coincides with the vector of the force line. Practical significance. In the laboratory, to study the bending deformations and their impact on the stability of the coal seam roof under external loads, it is advisable to use a model of a single width beam with a symmetrical section with supports, the type of which is determined by rock pressure control and secondary support of the maingate at the extraction layout of the coal mine.

The threat of outflow of individual deposits in systemically important banks of the Russian Federation: A retrospective analysis and regulatory outlook

2021 ◽  
Vol 27 (1) ◽  
pp. 4-21
Author(s):  
Yuliya S. EVLAKHOVA
Keyword(s):  
Statistical Analysis ◽  
Retrospective Analysis ◽  
Russian Federation ◽  
Too Big To Fail ◽  
Bank Run ◽  
Business Operations ◽  
The Russian Federation ◽  
The Stability ◽  
High Threat ◽  
Systemically Important Banks

Subject. The article focuses on the dynamics of individual deposits in the Russian systemically important banks as a factor of the stability of available resources. Objectives. I assess the threat of individual deposits outflowing from the Russian too-big-to-fail banks within 2015–2019. I correspondingly outline recommendations for mitigating the threat in the future. Methods. The study is based on methods of logic, comparative and statistical analysis. I devised and applied our own algorithm for classifying too-big-to-fail banks by threat of individual deposit outflow and its level. Results. Systemically important banks were found to have not been exposed to the high threat of bank run within 2015–2019. Three fundamental credit institutions were constantly exposed to the threat of individual deposit outflow. One of eleven systemic banks continuously demonstrated the low threat of individual deposit outflow. The rest of the banks were migrating among the low-threat and high-threat classes. Conclusions and Relevance. The Russian systemically important banks can refer to our findings to articulate their deposit policy, set and use digital accounts of retail customers. The Bank of Russian can rely on the analysis of the threat of individual deposit outflow and other data on financial and business operations of the banks and its sustainability as part of bank oversight procedures.

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