The Influences of Key Strata Compound Breakage on the Overlying Strata Movement and Strata Pressure Behavior in Fully Mechanized Caving Mining of Shallow and Extremely Thick Seams: A Case Study

In order to analyze the impact of compound breakage of key strata on overlying strata movement and strata pressure behavior during the fully mechanized caving mining in shallow and extremely thick seams, this paper took the 1322 fully mechanized caving face in Jindi Coal Mine in Xing County as the engineering background. Under the special mining and geological condition mentioned above, UDEC numerical simulation software was applied to research the engineering problems, and results of numerical simulation were verified through the in-site measurement. The research results showed that during the fully mechanized caving mining in shallow and extremely thick seams, the inferior key strata affected by mining movement behaved in the mode of sliding instability and could not form the stable structure of the voussoir beam after breaking and caving. In addition, the main key strata behaved in the mode of rotary instability, and the caving rocks behind the goaf were gradually compacted because of the periodic instability of the main key strata. With the continuous advance of the working face, the abutment pressure of the working face was affected by the compound breakage and periodic instability of both the inferior key strata and the main key strata, and the peaks of the abutment pressure presented small-big-small-big periodical change characteristics. Meanwhile, the risk of rib spalling ahead of the working face presented different levels of acute or slowing trends. The actual measurement results of ground pressure in the working face showed that, in the working process, the first weighting interval of the inferior key strata was about 51 m and its average periodic weighting interval was about 12.6 m, both of which were basically consistent with the results of numerical simulation. The research has great significance in providing theoretical guidance and practical experience for predicting and controlling the ground pressure under the similar mining and geological conditions.

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UDEC Numerical Simulation Research of Mining Overlying Strata Movement Regulation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.448-453.3884 ◽

2013 ◽

Vol 448-453 ◽

pp. 3884-3887 ◽

Cited By ~ 1

Author(s):

You Ling Fang

Keyword(s):

Numerical Simulation ◽

Vertical Direction ◽

Simulation Software ◽

Simulation Research ◽

Fracture Angle ◽

Strata Movement ◽

Object A ◽

Working Face ◽

Overlying Strata Movement ◽

Overlying Strata

The process of fractures developing of coal and rock and overlying strata movement is a temporal dynamic evolution process. In this paper, based on the research object a working face of a mine, using the UDEC numerical simulation software to research the movement of the working face upper strata in mining process, the results showed that the overlying strata forms "vertical three zones" in the vertical direction from bottom to top. Overlying strata above the goaf displays a fracture table with a trapezoid shape entirely; the cut side of the fracture angle is slightly larger than the working face side of the fracture angle. Numerical simulation calculation of the height of two zones will get a close consistent result to empirical formula. The conclusions have important guiding significance for reasonable arrangement of the gas exploitation.

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Study on the Structure Characteristics and Ground Pressure Behavior of Overlying Strata with Shallow Buried Coal Seam

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.3780 ◽

2011 ◽

Vol 255-260 ◽

pp. 3780-3785 ◽

Cited By ~ 2

Author(s):

Lei Yu ◽

Zhi Zhong Fan ◽

Gang Xu

Keyword(s):

Coal Seam ◽

Ground Subsidence ◽

Mine Pressure ◽

Structure Characteristics ◽

Pressure Behavior ◽

Ground Pressure ◽

Working Face ◽

Periodic Pressure ◽

Seam Mining ◽

Overlying Strata

The mine pressure behavior characters of shallow buried coal seam differed from both shallow seam mining and general depth seam. Mine pressure observation and numerical analysis were applied to research mine pressure behavior laws in fully mechanized face of shallow buried coal seam with thick bedrock and thin alluvium. It showed that the ground subsidence level phenomenon did not appear obviously although with obvious dynamic loading of fully mechanized face during the pressure period. The appearance was due to non-synchronized fracture from two key layers in the overlying rock layers and their interaction, which leaded to roof breaking initially and caving rocks with the form of an arch. Due to the periodic breaking and caving characteristics appearing as fully cut-down and arch alternately, the periodic pressure of shallow buried coal seam face showed as different size. The conclusion could be a reference for similar working face control.

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Study on Mountainous Shallow-Buried Coal Seam Mining Working Face Strata Behaviors and Overlying Strata Movement Features

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.121-126.2911 ◽

2011 ◽

Vol 121-126 ◽

pp. 2911-2916

Author(s):

Guo Lei Liu ◽

Ke Gong Fan ◽

Tong Qiang Xiao

Keyword(s):

Coal Seam ◽

Horizontal Displacement ◽

Simulation Software ◽

High Rate ◽

Strata Movement ◽

Working Face ◽

Element Simulation ◽

Valve Opening ◽

Seam Mining ◽

Overlying Strata

Through testing the mountainous shallow-buried coal seam mining working face strata behaviors in Faer mine field, it got the strata behaviors: it was of large roof pressure, high rate of safety valve opening in hydraulic support, and even some supports crushed or took separation between top beams and tail beams. Traditional method of calculating supports’ resistance can not be applied to mountainous shallow-buried coal seam mining working face. With the discrete element simulation software UDEC it analyzed the strata movement feature, and got that the overlying strata took collapse and horizontal displacement after mountainous shallow-buried coal seam mined, and the strata movement feature was different between reverse slope mining and positive slope mining.

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The Application of Similar Material in the Simulation of Overlying Strata Movement in High Inclined Seam in Dongbaowei Mine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.600.194 ◽

2012 ◽

Vol 600 ◽

pp. 194-198 ◽

Cited By ~ 1

Author(s):

Ming Ming Wen

Keyword(s):

Coal Seam ◽

Reference Value ◽

Geological Condition ◽

Similar Material ◽

Strata Movement ◽

Support Measures ◽

Working Face ◽

Overlying Strata Movement ◽

Similar Material Simulation ◽

Overlying Strata

Studying on the characteristics of the overlying strata movement in high inclined coal seam, the similar material is applied in the simulation model which was built based on the similar material simulation theory and high inclined seam geological condition of Dongbaowei coal mine. The picture and displacement of overlying strata were obtained from the similar material simulation. As a result, the characteristics of the fracture and movement of overlying strata above the full mechanized working face in high inclined seam. This paper proposes some support measures to improve the safety of the working face. These provide significance theoretical guidance and reference value for other working face in high inclined seam.

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Analysis on Key Strata’s Subsidence in Paste-Like Filling Face

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.524-527.525 ◽

2012 ◽

Vol 524-527 ◽

pp. 525-530

Author(s):

Jian Hao ◽

Yong Kui Shi ◽

Kuan Liu

Keyword(s):

Lower Layer ◽

Early Stage ◽

Stable State ◽

Key Strata ◽

Primary Stress ◽

Ground Pressure ◽

Working Face ◽

High Layer ◽

Supporting Force ◽

Overlying Strata

Using theoretical analysis and actually test research to analyze stress condition of filling body and average subsidence of the key strata, analysis shows that the average vertical stress in filling body was about 15Mpa when entering into stable state, which is equal to the primary stress, 13.75Mpa. The filling body could tighten the roof well and the filling body can support full weight of the overlying strata. The limestone, thickness of 5.3m, above the 81006 working face is the key strata of mining stope. On the interaction between ground pressure and the supporting force of filling body, the whole key strata subsided about 98.64mm on average theoretically, as the height meter monitored, the subsidence value of key strata was 108mm on average, conforms to the theoretical value, which proves the filling effect was good. At the early stage after filling, the roof subsided relatively faster as the filling body had not coagulated completely and the strength was lower. At this stage the roof was not tightened enough with the filling body, it subsided relatively faster in some certain limited space. After a while, the limestone, the key strata of mining stope, became stable for a short term, and then it would continue to subside until being stable under the disturbance of the high layer, because the movement of lower layer created some space for high layer.

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Overlying Strata Movement and Abutment Pressure Evolution Process of Fully Mechanized Top Coal Caving Mining in Extra Thick Coal Seam

Geofluids ◽

10.1155/2021/7839888 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Yongqiang Zhao ◽

Yingming Yang ◽

Xiaobin Li ◽

Zhiqi Wang

Keyword(s):

Coal Seam ◽

Abutment Pressure ◽

Stress Measurement ◽

Field Investigation ◽

Evolution Process ◽

Thick Coal Seam ◽

Strata Movement ◽

Overlying Strata Movement ◽

Pressure Evolution ◽

Overlying Strata

Taken overlying strata of fully mechanized top coal caving mining (FMTCCM) in 15 m extra thick coal seam as the research object, the comprehensive research methods such as field investigation, theoretical calculation, and numerical analysis are used to systematically analyze. During the mining of extra thick coal seam, the overlying strata form the structure of lower cantilever beam and upper hinged rock beam. The downward transmission caused by the interaction of this combined structure is the fundamental reason for the strong periodic ground pressure behavior of working face and roadway blow. The movement process of overlying strata movement is divided into four stages, and dynamic distribution characteristics of lateral abutment pressure in different stages are obtained. It is considered that the gob side roadway can be in a relatively stable overburden structure and stress environment during the stable stage of abutment pressure. The distribution range of the internal and external stress fields is determined, which provides a theoretical basis for the reasonable roadway layout. At last, the fracture position and abutment pressure evolution process of overlying strata along the goaf side of the extra thick coal seam are further verified by drilling stress measurement.

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A numerical simulation of realistic top coal caving intervals under different top coal thicknesses in longwall top coal caving working face

10.21203/rs.3.rs-243080/v1 ◽

2021 ◽

Author(s):

Chuang Liu ◽

Huamin Li

Keyword(s):

Numerical Simulation ◽

Coal Seam ◽

Distinct Element ◽

Simulation Models ◽

Simulation Software ◽

Thick Coal Seam ◽

Coal Recovery ◽

Working Face ◽

Longwall Top Coal Caving ◽

Selection Of

Abstract In the process of longwall top coal caving, the selection of the top coal caving interval along the advancing direction of the working face has an important effect on the top coal recovery. To explore a realistic top coal caving interval of the longwall top coal caving working face, longwall top coal caving panel 8202 in the Tongxin Coal Mine is used as an example, and 30 numerical simulation models are established by using Continuum-based Distinct Element Method (CDEM) simulation software to study the top coal recovery with 4.0 m, 8.0 m, 12.0 m, 16.0 m, 20.0 m and 24.0 m top coal thicknesses and 0.8 m, 1.0 m, 1.2 m, 1.6 m and 2.4 m top coal caving intervals. The results show that with an increase in the top coal caving interval, the single top coal caving amount increases. The top coal recovery is the highest with a 0.8 m top coal caving interval when the thickness of the top coal is less than 4.0 m, and it is the highest with a 1.2 m top coal caving interval when the coal seam thickness is greater than 4.0 m. These results provide a reference for the selection of a realistic top coal caving interval in thick coal seam caving mining.

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A Mechanical Model of the Overlying Rock Masses in Undersea Coal Mining and a Stress-Seepage Coupling Numerical Simulation

Advances in Civil Engineering ◽

10.1155/2018/8161498 ◽

2018 ◽

Vol 2018 ◽

pp. 1-14 ◽

Cited By ~ 1

Author(s):

Jie Fang ◽

Lei Tian ◽

Yanyan Cai ◽

Zhiguo Cao ◽

Jinhao Wen ◽

...

Keyword(s):

Numerical Simulation ◽

Coal Seam ◽

Coal Mining ◽

Water Inrush ◽

Mining Area ◽

Analysis Model ◽

Fractured Zones ◽

Working Face ◽

Seam Mining ◽

Overlying Strata

The water inrush of a working face is the main hidden danger to the safe mining of underwater coal seams. It is known that the development of water-flowing fractured zones in overlying strata is the basic path which causes water inrushes in working faces. In the engineering background of the underwater mining in the Longkou Mining Area, the analysis model and judgment method of crack propagation were created on the basis of the Mohr–Coulomb criterion. Fish language was used to couple the extension model into the FLAC3d software, in order to simulate the mining process of the underwater coal seam, as well as to analyze the initiation evolutionary characteristics and seepage laws of the fractured zones in the overlying strata during the advancing processes of the working face. The results showed that, during the coal seam mining process, the mining fractured zones which had been caused by the compression-shear and tension-shear were mainly concentrated in the overlying strata of the working face. Also, the open-off cut and mining working face were the key sections of the water inrush in the rock mass. The condition of the water disaster was the formation of a water inrush channel. The possible water inrush channels in underwater coal mining are mainly composed of water-flowing fractured zones which are formed during the excavation processes. The numerical simulation results were validated through the practical engineering of field observations on the height of water-flowing fractured zone, which displayed a favorable adaptability.

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Deformation Rules for Surrounding Rock in Directional Weakening of End Roofs of Thin Bedrocks and Ultrathick Seams

Advances in Civil Engineering ◽

10.1155/2020/8882374 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Fei Liu ◽

Zhanguo Ma ◽

Yongsheng Han ◽

Zhimin Huang

Keyword(s):

Abutment Pressure ◽

Main Roof ◽

Stability Control ◽

Surrounding Rock ◽

Western China ◽

Resource Exploitation ◽

Failure Characteristics ◽

Key Strata ◽

Working Face ◽

Geological Conditions

With the deployment of China’s energy strategy in the western regions, complex geological mining conditions such as thin bedrock and ultrathick seams in western China have caused a series of problems such as serious deformation of the surrounding rock at the ends of the working face and the increase in the lead abutment pressure of the roadways; the research on end roof deformation in the resource exploitation in western China has become one of the great demands of the industry. Based on the failure characteristics of rock mass, relying on the actual mining geological conditions of a coal mine in Inner Mongolia, the failure characteristics of the overlying rock strata under the influence of mining were simulated and analyzed using similar material simulation experiment, which intuitively reproduced the failure and deformation processes of the immediate roof, main roof, and key strata and revealed the mechanical mechanism of the directional weakening of the end roof. It is of great significance for the stability control of the surrounding rock at the end of the fully mechanized caving face in the thin bedrocks and ultrathick seams, reducing the abutment pressure of gate roadway and controlling the spontaneous combustion of residual coal in the goaf.

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