scholarly journals Numerical analysis of inter-panel pillars in the bump prone conditionals of the Alardinskaya mine

2021 ◽  
Vol 326 ◽  
pp. 00009
Author(s):  
Andrey Sidorenko ◽  
Vyacheslav Alekseev ◽  
Vladimir Ivanov
Keyword(s):  
Numerical Modeling ◽  
Numerical Analysis ◽  
Fire Hazard ◽  
Coal Seams ◽  
Longwall Panel ◽  
Barrier Pillar ◽  
Endogenous Fire ◽  
Yield Pillars ◽  
Reference Pressure ◽  
Gas Bearing

The purpose of the paper is to substantiate the width of the barrier and yield pillars for the application of a new seam development scheme in the conditions of the Alardinskaya mine (Russia). The Alardinskaya mine develops gas-bearing coal seams that are prone to spontaneous combustion and are hazardous due to rock bumps, which leads to frequent accidents. The analysis of the world experience of mining seams being hazardous to rock bumps showed that safe mining with longwalls can be provided by a system of inter-panel pillars: very wide barrier pillar and two yield pillars. Numerical modeling using the finite element method was carried out to assess the possibility of reducing the barrier pillar width in order to decrease the volume of coal losses in the subsoil. The model of rock massif was created in Ansys mechanical software. Numerical modeling of the longwall panel development with longwalls was carried out at various widths of broad and yield pillars. The analysis outcomes of the vertical stresses diagrams in the seams are presented for different parts of the longwall panel. The rational parameters of the pillar system, ensuring the minimization of the reference pressure influence from the previously worked-out column and the reference pressure of the operating longwall, are determined as a result of numerical analysis. The conclusion is made about the expediency of the technological scheme application proposed by the authors in the conditions of the Alardinskaya mine to reduce the endogenous fire hazard and the danger of rock bumps.

Using pillar-free mining technologies in gently dipping and self-ignitable coal seams

2020 ◽  
pp. 64-77
Author(s):  
D. D. Golubev
Keyword(s):  
Fire Hazard ◽  
Coal Pillar ◽  
Kuznetsk Coal ◽  
Coal Seams ◽  
State Behavior ◽  
Mining Depth ◽  
Study Results ◽  
Endogenous Fire ◽  
Determination Of Parameters ◽  
Coal Seam Thickness

Gently dipping coal seams of the Kuznetsk Coal Basin are cut exclusively by longwalls with preliminary drivage of twin gate ways. At the same time, the source of self-ignition in mines is pillars of coal left in mined-out areas. Endogenous fire hazard grows with higher losses of loose coal in mined-out areas due to a persistent increase in mining depth and in size of longwalls. This research aims at development of an alternative mining technology for gently dipping coal seams to reduce the risk of initiation of self-ignition sources in mined-out areas and at the determination of parameters of the technology elements as functions of coal seam thickness and mining depth. A new concept of preparatory works and actual mining in selfignitable coal seams is described. The study results obtained with numerical modeling of the stress-state behavior of rock mass and the developed technology elements at different stages of longwalling are presented. The studies show that endogenous fire hazard is reduced by means of extraction of coal pillar on the same line with face and due to elimination of aerological connection between the operating longwall and earlier mined-out area owing to construction of a separation belt made of solidifying materials between them. The cross-effect of the widths of the solidifying material belt and coal pillar as the elements of the developed technology is estimated.

Use of Destressing Drilling to Ensure Safety of Donbass Gas-bearing Coal Seams Extraction

2019 ◽  
pp. 7-11
Author(s):  
V.S. Brigida ◽  
◽  
Yu.V. Dmitrak ◽  
O.Z. Gabaraev ◽  
V.I. Golik ◽  
...  
Keyword(s):  
Coal Seams ◽  
Gas Bearing

Upon Impact Numerical Modeling of Foam Materials

2017 ◽  
Vol 54 (2) ◽  
pp. 195-202
Author(s):  
Vasile Nastasescu ◽  
Silvia Marzavan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Numerical Analysis ◽  
Numerical Methods ◽  
Boundary Conditions ◽  
General Character ◽  
Foam Material ◽  
Various Boundary Conditions ◽  
Specific Behaviour

The paper presents some theoretical and practical issues, particularly useful to users of numerical methods, especially finite element method for the behaviour modelling of the foam materials. Given the characteristics of specific behaviour of the foam materials, the requirement which has to be taken into consideration is the compression, inclusive impact with bodies more rigid then a foam material, when this is used alone or in combination with other materials in the form of composite laminated with various boundary conditions. The results and conclusions presented in this paper are the results of our investigations in the field and relates to the use of LS-Dyna program, but many observations, findings and conclusions, have a general character, valid for use of any numerical analysis by FEM programs.

Numerical analysis of the shear strength of circular reinforced concrete columns subjected to cyclic lateral loads using linear genetic programming

2020 ◽  
Vol 37 (7) ◽  
pp. 2517-2537
Author(s):  
Mostafa Rezvani Sharif ◽  
Seyed Mohammad Reza Sadri Tabaei Zavareh
Keyword(s):  
Numerical Modeling ◽  
Shear Strength ◽  
Reinforced Concrete ◽  
Numerical Analysis ◽  
Genetic Programming ◽  
Linear Genetic Programming ◽  
Rc Columns ◽  
Content Type ◽  
Alternative Approach ◽  
Engineering Problems

Purpose The shear strength of reinforced concrete (RC) columns under cyclic lateral loading is a crucial concern, particularly, in the seismic design of RC structures. Considering the costly procedure of testing methods for measuring the real value of the shear strength factor and the existence of several parameters impacting the system behavior, numerical modeling techniques have been very much appreciated by engineers and researchers. This study aims to propose a new model for estimation of the shear strength of cyclically loaded circular RC columns through a robust computational intelligence approach, namely, linear genetic programming (LGP). Design/methodology/approach LGP is a data-driven self-adaptive algorithm recently used for classification, pattern recognition and numerical modeling of engineering problems. A reliable database consisting of 64 experimental data is collected for the development of shear strength LGP models here. The obtained models are evaluated from both engineering and accuracy perspectives by means of several indicators and supplementary studies and the optimal model is presented for further purposes. Additionally, the capability of LGP is examined to be used as an alternative approach for the numerical analysis of engineering problems. Findings A new predictive model is proposed for the estimation of the shear strength of cyclically loaded circular RC columns using the LGP approach. To demonstrate the capability of the proposed model, the analysis results are compared to those obtained by some well-known models recommended in the existing literature. The results confirm the potential of the LGP approach for numerical analysis of engineering problems in addition to the fact that the obtained LGP model outperforms existing models in estimation and predictability. Originality/value This paper mainly represents the capability of the LGP approach as a robust alternative approach among existing analytical and numerical methods for modeling and analysis of relevant engineering approximation and estimation problems. The authors are confident that the shear strength model proposed can be used for design and pre-design aims. The authors also declare that they have no conflict of interest.

The current state of the problem of predicting spontaneous combustion and explosiveness of sulfide ores and host rocks at a depth of more than 1500 m.

2021 ◽  
pp. 77-80
Author(s):  
Z.G. Ufatova
Keyword(s):  
Moisture Content ◽  
Air Temperature ◽  
Initial Phase ◽  
Spontaneous Combustion ◽  
Fire Hazard ◽  
Free Access ◽  
Sulfide Ores ◽  
Working Face ◽  
Time In Treatment ◽  
Endogenous Fire

The mining factors of ore fire hazard during mining of the lower horizons of the Oktyabrskiy and Talnakhskiy northern deposits are considered. It is noted that the probability of self-heating of sulfide ores and the sulfide dust’s tendency to spontaneous combustion and explosiveness in certain sections of rich sulfide copper-nickel ores are quite high. The oxidation of sulfide ores occurs continuously due to the absorption of oxygen from the mine atmosphere and is accompanied by the release of heat. The oxidation can be accompanied by intense heating of the ore in mining conditions, with the accumulation of large volumes of broken rock mass for a long time in treatment and preparation workings and with free access of air to the bulk of the ore mass. The processes of ore and rock oxidation are especially intense when their moisture content is 1–4%. When the ore is heated above 35 °C, sulfurous gas (SO2) may be released. The main signs of the above-mentioned oxidative processes’ development and signs of the initial phase of a possible underground endogenous fire are indicated along with a constant increase in the temperature of the air coming from the bottom of the face. It is noted that in case of detecting at least one of the signs of a possible underground endogenous fire’s initial phase, urgent measures are taken to improve the ventilation of this working face, to ensure maximum intensity of shipped ore from the fresh stream and the content of sulfurous gas and hydrogen sulfide and mine air temperature are determined every 4 hours. If after two days on the outgoing stream there is no decrease in the content of sulfur dioxide and air temperature, then it should be considered that an endogenous fire has occurred. Measures for the prevention, localization and elimination of foci of spontaneous combustion are given. As an additional safety measure, it is recommended to moisten the dust, since sulfide dust becomes non-explosive at a moisture content of 9–9,5%, and at a humidity of 10% the dust does not transmit an explosive impulse.

Methane Injury-Risk at the Russian Mines

2021 ◽  
pp. 69-74
Author(s):  
V.S. Zaburdayev ◽  
◽  
S.N. Podobrazhin ◽  
Keyword(s):  
Injury Risk ◽  
Electrical Equipment ◽  
Coal Deposit ◽  
Coal Seams ◽  
Mining Operations ◽  
Mining Conditions ◽  
Scientific Substantiation ◽  
And Control ◽  
Gas Bearing ◽  
Engineering Personnel

Conditions are given concerning the development of methane-bearing coal seams in Russia, the chronology of injuries from explosions and outbreaks of methane-air mixtures at the Russian mines for a quarter of a century of developing coal seams at the nine deposits. The emergency was studied in 174 mine incidents, which occurred mainly at the mines of Kuzbass, Vorkuta coal deposit, Eastern Donbass, Chelyabinsk basin, Primorye and Sakhalin. Emergency objects - excavation areas, preparation faces and mined-out areas of the mines. The sources of ignition of methane-air mixture are drilling and blasting works in the faces, malfunctioning of electrical equipment, frictional sparking, endogenous fires, and smoking in the mines. The most injury-risk for methane are steep and steeply inclined mines. The need in the scientific substantiation of the decisions taken for prevention or reduction of the methane injury-risk at the mines is noted in the article. An important role is assigned to the choice of ways to achieve this goal considering the geological and mining conditions of the development of gas-bearing coal seams. As an example, the conditions, methods, and parameters of mining operations at the excavation areas of four mines are given, where occurred the catastrophic explosions of methane-air and methane-dust-air mixtures. The reasons are gross violations of safety rules during mining operations, incompetence of the mine engineering personnel, design, and control organizations in matters of safety during the underground work at the gas-hazardous mines with an extensive network of workings. This resulted in the death of miners and mine rescuers, the destruction of mine workings, equipment and devices, underground fires. Recommendations are given for reducing the level of methane injury-risk at the methane-rich mines.

Optimization of Coal Seam Connectivity via Multi-Seam Pinpoint Fracturing Operations in the Walloons Coal Measures, Surat Basin

2021 ◽  
Author(s):  
Vibhas J. Pandey ◽  
Sameer Ganpule ◽  
Steven Dewar
Keyword(s):  
Coal Seam ◽  
History Matching ◽  
Design Matrix ◽  
Coal Seams ◽  
Major Step ◽  
Well Completion ◽  
Eastern Australia ◽  
Treatment Designs ◽  
Coal Measures ◽  
Gas Bearing

Abstract The Walloons coal measures located in Surat Basin (eastern Australia) is a well-known coal seam gas play that has been under production for several years. The well completion in this play is primarily driven by coal permeability which varies from 1 Darcy or more in regions with significant natural fractures to less than 1md in areas with underdeveloped cleat networks. For an economic development of the latter, fracturing treatment designs that effectively stimulate numerous and often thin coals seams, and enhance inter-seam connectivity, are a clear choice. Fracture stimulation of Surat basin coals however has its own challenges given their unique geologic and geomechanical features that include (a) low net to gross ratio of ~0.1 in nearly 300 m (984.3 ft) of gross interval, (b) on average 60 seams per well ranging from 0.4 m to 3 m in thickness, (c) non-gas bearing and reactive interburden, and (d) stress regimes that vary as a function of depth. To address these challenges, low rate, low viscosity, and high proppant concentration coiled tubing (CT) conveyed pinpoint stimulation methods were introduced basin-wide after successful technology pilots in 2015 (Pandey and Flottmann 2015). This novel stimulation technique led to noticeable improvements in the well performance, but also highlighted the areas that could be improved – especially stage spacing and standoff, perforation strategy, and number of stages, all aimed at maximizing coal coverage during well stimulation. This paper summarizes the findings from a 6-well multi-stage stimulation pilot aimed at studying fracture geometries to improve standoff efficiency and maximizing coal connectivity amongst various coal seams of Walloons coal package. In the design matrix that targeted shallow (300 to 600 m) gas-bearing coal seams, the stimulation treatments varied in volume, injection rate, proppant concentration, fluid type, perforation spacing, and standoff between adjacent stages. Treatment designs were simulated using a field-data calibrated, log-based stress model. After necessary adjustments in the field, the treatments were pumped down the CT at injection rates ranging from 12 to 16 bbl/min (0.032 to 0.042 m3/s). Post-stimulation modeling and history-matching using numerical simulators showed the dependence of fracture growth not only on pumping parameters, but also on depth. Shallower stages showed a strong propensity of limited growth which was corroborated by additional field measurements and previous work in the field (Kirk-Burnnand et al. 2015). These and other such observations led to revision of early guidelines on standoff and was considered a major step that now enabled a cost-effective inclusion of additional coal seams in the stimulation program. The learnings from the pilot study were implemented on development wells and can potentially also serve as a template for similar pinpoint completions worldwide.

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