scholarly journals Laboratory research of vibration impact parameters on the coal seam through host rocks

2019 ◽  
Vol 109 ◽  
pp. 00069
Author(s):  
Oleksandr Petukh ◽  
Kostiantyn Sofiiskyi ◽  
Dmytro Zhytlonok
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Laboratory Research ◽  
Hydraulic Systems ◽  
Working Face ◽  
Fundamental Possibility ◽  
Vibration Impact ◽  
Basic Parameters ◽  
Bench Testing ◽  
Host Rocks

On the basis of mechanized roof supports, the hydraulic systems of vibrators operating as compact vibrators for controlling the condition of the coal and rock mass through host rocks are selected and refined. Bench testing of vibrator systems operating in continuous and pulsed modes with automatic control were held. The basic parameters of the systems of vibrators are established, and the fundamental possibility of their work in the working face of gas-dangerous mines was proved.

scholarly journals Stress and deformation analysis of gob-side pre-backfill driving procedure of longwall mining: a case study

2021 ◽  
Author(s):  
Rui Wu ◽  
Penghui Zhang ◽  
Pinnaduwa H. S. W. Kulatilake ◽  
Hao Luo ◽  
Qingyuan He
Keyword(s):  
Rock Mass ◽  
Stress Distribution ◽  
Coal Seam ◽  
Abutment Pressure ◽  
Longwall Mining ◽  
Vertical Stress ◽  
Floor Level ◽  
Working Face ◽  
Floor Heave ◽  
Stress And Deformation

AbstractAt present, non-pillar entry protection in longwall mining is mainly achieved through either the gob-side entry retaining (GER) procedure or the gob-side entry driving (GED) procedure. The GER procedure leads to difficulties in maintaining the roadway in mining both the previous and current panels. A narrow coal pillar about 5–7 m must be left in the GED procedure; therefore, it causes permanent loss of some coal. The gob-side pre-backfill driving (GPD) procedure effectively removes the wasting of coal resources that exists in the GED procedure and finds an alternative way to handle the roadway maintenance problem that exists in the GER procedure. The FLAC3D software was used to numerically investigate the stress and deformation distributions and failure of the rock mass surrounding the previous and current panel roadways during each stage of the GPD procedure which requires "twice excavation and mining". The results show that the stress distribution is slightly asymmetric around the previous panel roadway after the “primary excavation”. The stronger and stiffer backfill compared to the coal turned out to be the main bearing body of the previous panel roadway during the "primary mining". The highest vertical stresses of 32.6 and 23.1 MPa, compared to the in-situ stress of 10.5 MPa, appeared in the backfill wall and coal seam, respectively. After the "primary mining", the peak vertical stress under the coal seam at the floor level was slightly higher (18.1 MPa) than that under the backfill (17.8 MPa). After the "secondary excavation", the peak vertical stress under the coal seam at the floor level was slightly lower (18.7 MPa) than that under the backfill (19.8 MPa); the maximum floor heave and maximum roof sag of the current panel roadway were 252.9 and 322.1 mm, respectively. During the "secondary mining", the stress distribution in the rock mass surrounding the current panel roadway was mainly affected by the superposition of the front abutment pressure from the current panel and the side abutment pressure from the previous panel. The floor heave of the current panel roadway reached a maximum of 321.8 mm at 5 m ahead of the working face; the roof sag increased to 828.4 mm at the working face. The peak abutment pressure appeared alternately in the backfill and the coal seam during the whole procedure of "twice excavation and mining" of the GPD procedure. The backfill provided strong bearing capacity during all stages of the GPD procedure and exhibited reliable support for the roadway. The results provide scientific insight for engineering practice of the GPD procedure.

scholarly journals Outburst cavity formation in the working face driven along the outburst-prone coal seam

2020 ◽  
Vol 168 ◽  
pp. 00052
Author(s):  
Oleksandr Krukovskyi ◽  
Viktoriia Krukovska ◽  
Wen Zhang
Keyword(s):  
Mathematical Model ◽  
Coal Seam ◽  
Mining Operation ◽  
Production Equipment ◽  
Coupled Processes ◽  
Gas Filtration ◽  
Working Face ◽  
Calculation Results ◽  
Coal And Gas Outbursts ◽  
Host Rocks

In Donbas coal mines, coal and gas outbursts present a major risk for the mining operation safety. Rapidly released energy can cause serious damage to the mine’s personnel and production equipment. Modern numerical methods allow modeling complex physical processes occurred during the coal and gas outbursts. The mathematical model was developed for the coupled processes of the rock massif deformation and gas filtration in the mine face near the tectonic dislocation. When solving the problem, the finite element method was used. The calculation results of the stresses, inelastic deformation zones, pressures of methane and configuration of cavity of the coal and gas outburst are represented in the paper. It is shown that an outburst cavity is formed inside the coal seam and is bounded from above and from below by the host rocks. The calculated geometry of the fracture cavity at the gas-dynamic phenomena in the mine working face coincides with actual data obtained in the mines of Donbas and, therefore, confirms the adequacy of the developed mathematical model.

scholarly journals Stability of a Roadway below a Coal Seam under Dynamic Pressure: A Case Study of the 11123 Floor Gas Drainage Roadway of a Mine in Huainan, China

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Pingsong Zhang ◽  
Yuanchao Ou ◽  
Chang Liu ◽  
Binyang Sun ◽  
Chong Xu
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Dynamic Pressure ◽  
Time Domain Reflectometry ◽  
Surrounding Rock ◽  
Monitoring Method ◽  
Gas Drainage ◽  
Gas Outburst ◽  
Working Face ◽  
Seam Mining

Coal and gas outburst is an important risk faced by coal seam mining in the Huainan region of China. In order to control gas outburst, the gas is predrained by digging a floor gas drainage roadway. To study deformation due to dynamic pressure, the failure characteristics of the floor, and their effect on the stability of the floor gas drainage roadway, a comprehensive monitoring method combining Brillouin optical time-domain reflectometry- (BOTDR-) distributed fiber optics and self-potential exploration was adopted. Dynamic data monitoring of the rock strata between the 11123 working face floor and the floor gas drainage roadway of a mine in Huainan was carried out. The field data obtained showed that, when stabilized by rock bolts and other fixed components in the surrounding rock mass of the floor gas drainage roadway, under the influence of mining, the area of concentrated stress appeared at a depth of 20.7 m, when cracks eventually formed, but the overall structural stability of the surrounding rock mass remained good. The stress distribution and crack evolution of the bottom plate under the influence of dynamic pressure showed spatiotemporal characteristics. Of these, the effect of the lead support stress was 107.48 m, and the range of effect of the hysteresis stress was 34.42 m. When the working face mining position arrives and is far from the monitoring station, the failure depth of floor rock stratum shows the following rule: unchanged in the early stage, deepened continuously in the middle stage, and finally remained stable. It takes about eight days for the dynamic adjustment of this process to finally stabilize. The results of this study can provide guidance for devising suitable procedures for carrying out intelligent green safety mining and for warning about the hazards of roadway damage.

scholarly journals Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

The Adaptation Analysis of the Fully Mechanized Coal Mining Face of Huopu Mine’s Third Soft Coal Seam

2014 ◽  
Vol 1049-1050 ◽  
pp. 335-338 ◽  
Author(s):  
Fa Quan Liu ◽  
Xue Wen Geng ◽  
Yong Che ◽  
Xiang Cui
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Geological Condition ◽  
Soft Coal ◽  
Working Face ◽  
Mining Face ◽  
Soft Coal Seam ◽  
Working Resistance

To get the maximum coal in front of the working face of the 17# coal seam, we installed a longer beam which is 1.2m in length in the leading end of the original working face supports ZF3000/17/28, and know that working face supports’ setting load and working resistance are lower .We changed the original supports with shield supports ZY3800/15/33 that are adaptable in the geological condition and got the favorable affection.

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