scholarly journals Determination of working resistance based on movement type of the first subordinate key stratum in a fully mechanized face with large mining height

2019 ◽  
Vol 7 (3) ◽  
pp. 777-798 ◽  
Author(s):  
Bo Li ◽  
Yunpei Liang ◽  
Quanle Zou
Keyword(s):  
Key Stratum ◽  
Large Mining Height ◽  
Movement Type ◽  
Working Resistance ◽  
Mining Height

scholarly journals Key Stratum Structure and Support Working Resistance of Longwall Face with Large Mining Height in the Shallow Coal Seams, China

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Qingxiang Huang ◽  
Jinlong Zhou ◽  
Jian Cao
Keyword(s):  
Coal Seam ◽  
Physical Simulation ◽  
Longwall Face ◽  
Beam Structure ◽  
Key Stratum ◽  
Immediate Roof ◽  
Large Mining Height ◽  
Shallow Coal Seam ◽  
Working Resistance ◽  
Mining Height

The fully mechanized mining with large mining height is the main method for high yield and efficient coal mining in China. The key stratum structure (KSS) is the basis of revealing the mechanism of roof weighting and determination of support working resistance of the longwall face with large mining height (LFLMH) in the shallow coal seam. The height of the caving zone at LFLMH is large, the thick immediate roof forms the “short cantilever beam” structure commonly, and the hinge layer of the overlying key stratum will move upward to the higher position. The “high position oblique step voussoir beam” structure of single-key stratum (SKS) and “oblique step voussoir beam and voussoir beam” structure of double-key stratum (DKS) in the shallow coal seam were proposed with physical simulation and Universal Distinct Element Code (UDEC). The analysis of the KSS and numerical simulation reveals the mechanism of strong roof weighting at the SKS longwall face and large-small alternate periodic weighting at the DKS longwall. It is concluded that the large static load caused by the “equivalent immediate roof (EIR)” is the basic load, and the instability load of the KSS is the additional dynamic load of support. Besides, the calculation methods of the reasonable support working resistance at LFLMH were obtained and verified with engineering applications.

scholarly journals Research on the Influence of the Key Stratum Position on the Support Working Resistance during Large Mining Height Top-Coal Caving Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Baisheng Zhang ◽  
Zhiping Yang ◽  
Chunxu Ji ◽  
Zefeng Guo ◽  
Haoyang Li
Keyword(s):  
Mining Method ◽  
Thick Coal Seam ◽  
Key Stratum ◽  
Movement Characteristics ◽  
Geological Conditions ◽  
Large Mining Height ◽  
Working Resistance ◽  
Mining Height ◽  
Overlying Strata ◽  
Layer Position

In recent years, in order to increase the coal recovery rate, the large mining height fully mechanized top-coal caving mining has been widely used because it has the advantages of both fully mechanized mining method and large mining height mining method. When this mining technology is used to exploit thick coal seam under upper goaf, the movement characteristics of the overlying strata and the bearing structure formed by the broken rock are complicated, which results in the abnormal pressure during mining, such as severe coal slabs and hydraulic supports being crushed. The key to solve these problems is to study the movement law and the structural evolution characteristics of the overlying strata during large mining height fully mechanized top-coal caving mining, and the movement characteristics of the overlying strata are all determined by the layer-position of the key stratum. UDEC models with different layer-position of the key stratum are established to investigate the influence of the key stratum position on the support working resistance during large mining height top-coal caving mining. Through comprehensive research, the source of support resistance comes from under different geological conditions was analyzed, and the formula for estimating the maximum support working resistance was deduced. In addition, in order to release the severe pressure during large mining height fully mechanized top-coal caving mining, it is recommended to use hydraulic fracturing method to weaken the key stratum in situ.

scholarly journals Determination of Optimal Extrication Location of High Extraction Roadway of Large-Mining-Height Fully Mechanized Face

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Xue-bo Zhang ◽  
Ming Yang
Keyword(s):  
Gas Extraction ◽  
Horizontal Distance ◽  
High Position ◽  
Working Face ◽  
Extraction Site ◽  
Large Mining Height ◽  
Porosity And Permeability ◽  
Permeability Distribution ◽  
Mining Height

Determining the optimal extrication location of the high extraction roadway can improve the gas extrication effect of highly gassy mine and solve the problem of gas concentration overrun at the upper corner, which is of great significance to safety and efficient mine production. According to the actual situation of mine, the gas gushing amount in the goaf, pressure difference at both ends of the working face, the 3D porosity, and permeability distribution of the caving zone and fissure zone were obtained by field measurement and numerical calculation. Through theoretical calculation, the proper extraction site of a high-position alley was determined. On this basis, the optimal extraction site of a high-position alley was determined by numerical analysis of the gas extraction effect at different sites. The results show that as the perpendicular distance between high-position alley and goaf floor increases, the gas extraction amount increases first and then decreases. The concentration of extraction gas gradually increases, and the increasing trend is gradually diminished. With the increase of the horizontal distance between the air return way and the high-position alley, the gas extraction amount and gas extraction concentration increase first and then decrease. The optimal extraction site of a high-position alley should be 39 m vertically away from the goaf floor and 30 m horizontally away from the air return way.

scholarly journals Research on Surface Failure Law of Working Faces in Large Mining Height and Shallow Buried Coal Seam

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Zhenhua Li ◽  
Yingkun Pang ◽  
Yongsheng Bao ◽  
Zhanyuan Ma
Keyword(s):  
Near Field ◽  
Mining Area ◽  
Surface Cracks ◽  
Large Space ◽  
Key Strata ◽  
Key Stratum ◽  
Surface Failure ◽  
Working Face ◽  
Large Mining Height ◽  
Mining Height

In the process of high-intensity and large-space mining in Shendong mining area, various surface cracks are generated on the surface, resulting in serious damage to the surface buildings and the local ecological environment. To study the influence of overlying rock movement on surface failure of near-field single key strata of near-shallow buried and large mining height working face, the relationship between overburden movement, strata pressure appearance, and surface failure at working face 52307 in Daliuta mining area was analyzed by field measurement and numerical simulation. The results show the following: (1) there is only one thick and hard key stratum in the overburden of large mining height and near-shallow buried working face. Under the condition of presplitting roof blasting, the first weighting step is still as high as 95 m, and the periodic breaking step of roof is 20–30 m. During the weighting, the working resistance of support is still close to the rated resistance. (2) The single key stratum plays an obvious role in controlling overburden movement. After the first weighting of the working face, a stepped subsidence crack appears on the surface within a short time, and the crack lags behind the working face for about 5 m. (3) During each periodic weighting process, the breaking and subsidence of key blocks are accompanied by surface cracks.

A Study on the Roof Fracture Mechanism of Large Cutting Height Workface in Shallow Thick Coal Seam

2011 ◽  
Vol 347-353 ◽  
pp. 183-188 ◽  
Author(s):  
Ping Wei Xing ◽  
Xuan Min Song ◽  
Yu Ping Fu
Keyword(s):  
Coal Seam ◽  
Mechanical Model ◽  
Calculation Formula ◽  
Thick Coal Seam ◽  
Key Stratum ◽  
Horizontal Pressure ◽  
Working Resistance ◽  
Cutting Height ◽  
Theoretical Results ◽  
Mining Height

Based on the high mining height of large cutting height workface in shallow thick coal seam and the few falling waste rock in goaf, the key roof can not be supported effectively, the facture mechanical model of key roof was established. The theoretical calculation formula of key stratum fracture step and working resistance of support were obtained by using fracture mechanics. The results show that the fracture step of key roof relate to not only the mechanical character of key roof and the load of overlaying rock seam, but also the working resistance of support and horizontal pressure in key roof. The reasonable working resistance of support and the step of roof fracture were analyzed in 1-2coalmine 51104 face of a mine in Dongsheng area. The theoretical results are well agreeable with the field measured results.

Study on rib spalling control of shortwall drilling mining technology with a large mining height

2021 ◽  
Vol 14 (3) ◽  
Author(s):  
Yong Yuan ◽  
Cheng Zhu ◽  
Hongmin Wei ◽  
Chaofeng Yuan ◽  
Zhongshun Chen
Keyword(s):  
Mining Technology ◽  
Large Mining Height ◽  
Mining Height
Sign in / Sign up

Export Citation Format

Share Document