scholarly journals Study on Influence Laws of Strata Behaviors for Shallow Coal Seam Mining beneath Gully Terrain

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhiqiang Wang ◽  
Jingkai Li ◽  
Chao Wu ◽  
Wenyu Lv ◽  
Jiao Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
Coal Seam ◽  
Key Stratum ◽  
Fundamental Cause ◽  
Shallow Coal Seam ◽  
Mining Face ◽  
Seam Mining ◽  
Working Resistance ◽  
Strong Dynamic

The study on influence laws of strata behaviors is the basic guarantee of safety mining for shallow coal seam beneath gully terrain. Taking 3302 mining face of Zhujiamao Coal Mine as the engineering background, the laws of strata behaviors for shallow coal seam mining beneath gully terrain are studied by field detection, theoretical analysis, and numerical simulation. The strata pressure observation and the hydraulic support working resistance show that the dynamic strata behaviors appear violently during mining beneath the gully bottom. The theoretical analysis shows that the rotation and breaking of key stratum beneath gully bottom under nonuniform load is the fundamental cause of strong dynamic strata behaviors. The numerical simulation of overburden movement and fissure development characteristics shows that the strata behaviors beneath the gully bottom are stronger than the strata behaviors beneath other areas. Additionally, according to the laws of dynamic strata behaviors, the safety measures for mining beneath gully bottom are put forward.

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.

Effects of Key Stratum Location on Hydraulic Conductivity Fracture Zone

2012 ◽  
Vol 170-173 ◽  
pp. 1179-1186
Author(s):  
Cheng Yang ◽  
Hai Bo Bai ◽  
Hu Ren Rong ◽  
Hai Long Li ◽  
Xiao Qi Wei
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Conductivity ◽  
Theoretical Analysis ◽  
Coal Seam ◽  
Fracture Zone ◽  
Main Channel ◽  
Winkler Foundation ◽  
Key Stratum ◽  
Caving Zone ◽  
Primary Key

The hydraulic conductivity fracture zone is the main channel causing inrush disaster in mine. This paper makes a few analysis on the effect of the location of primary key stratum through the theoretical analysis and numerical simulation. The results show that: (1). When the distance from key stratum to coal seam is about 3 times than the height of coal seam, the hydraulic conductivity fracture zone is higher than normal but the caving zone is lower than normal. When the distance from key stratum to coal seam is about 11 times than the height of coal seam, the hydraulic conductivity fracture zone is lower than normal but the caving zone is higher than normal; (2). The effect of Winkler foundation is obvious when the distance from key stratum to coal seam is 7 times than the height of coal seam, more even but the inverse is not; (3). We can certain whether the key stratum is fractured or not according to the hypothetical rock cohesive force expediently.

Research on Rational Width of Entry Protection Coal-Pillar in Large Mining Height Work-Face of Shallow Coal Seam

2014 ◽  
Vol 1010-1012 ◽  
pp. 1461-1466
Author(s):  
Xin Bin Xu ◽  
Bang Jun Wang ◽  
Ting Feng Cui
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Theoretical Calculation ◽  
Coal Pillar ◽  
Engineering Practice ◽  
Large Mining Height ◽  
Shallow Coal Seam ◽  
Mining Face ◽  
Mining Height

For the study on the problem of rational width of entry protection coal-pillar, according to the gateway of 5103 mining face in Heshan Mine, through theoretical calculation and numerical simulation, rational width of entry protection coal-pillar was educed, which was 25 m. The roof and floor and 2-sides deformation were both 35 mm through engineering practice, and its feasibility was demonstrated, which provided some theoretical references for preserving reasonable coal-pillar for the similar coalface with large mining height.

scholarly journals Subsidence Prediction of Overburden Strata and Ground Surface in Shallow Coal Seam Mining

2021 ◽  
Author(s):  
Jian Cao ◽  
Qingxiang Huang ◽  
Lingfei Guo
Keyword(s):  
Coal Seam ◽  
Physical Simulation ◽  
Soil Layer ◽  
Ground Surface ◽  
In Situ Observation ◽  
Key Stratum ◽  
Shallow Coal Seam ◽  
Seam Mining ◽  
Overburden Strata

Abstract Shallow coal seam with thick soil layer is widely reserved in the Jurassic Coalfield, Western China, mining-induced subsidence represents complex characteristics. Combining with physical simulation, theoretical analysis and in-situ observation, the overburden strata structure in dip direction were revealed, and the subsidence prediction models were established, based on this, the subsidence equations of overburden strata and ground surface were proposed. The results show that after shallow coal seam mining, based on the subsidence and movement characteristics, the overburden strata structure can be divided into three zones, which are "boundary pillar F-shape zone" (BPZ), "trapezoid goaf zone" (TGZ) and "coal pillar inverted trapezoidal zone" (CPZ). The subsidence of overburden strata depends on the key stratum, while the subsidence of soil layer depends on the bedrock subsidence basin, which is between the bedrock and thick soil layer. The bedrock subsidence is mainly related to mining height and bulking coefficient in TGZ, while it is mainly affected by mining height and distribution load on the key stratum in BPZ and CPZ. According to physical simulation and theoretical model, the maximum surface subsidence of No.1–2 seam mining in Ningtiaota coal mine are 1.1m and 1.07m respectively, which is basically consistence with the result of in-situ observation (1.2m).

scholarly journals Subsidence prediction of overburden strata and ground surface in shallow coal seam mining

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jian Cao ◽  
Qingxiang Huang ◽  
Lingfei Guo
Keyword(s):  
Coal Seam ◽  
Physical Simulation ◽  
Soil Layer ◽  
Ground Surface ◽  
In Situ Observation ◽  
Key Stratum ◽  
Shallow Coal Seam ◽  
Seam Mining ◽  
Overburden Strata

AbstractShallow coal seam with thick soil layer is widely reserved in the Jurassic Coalfield, Western China, mining-induced subsidence represents complex characteristics. Combining with physical simulation, theoretical analysis and in-situ observation, the overburden strata structure in dip direction were revealed, and the subsidence prediction models were established, based on this, the subsidence equations of overburden strata and ground surface were proposed. The results show that after shallow coal seam mining, based on the subsidence and movement characteristics, the overburden strata structure can be divided into three zones, which are "boundary pillar F-shape zone" (BPZ), "trapezoid goaf zone" (TGZ) and "coal pillar inverted trapezoidal zone" (CPZ). The subsidence of overburden strata depends on the key stratum, while the subsidence of soil layer depends on the bedrock subsidence basin, which is between the bedrock and thick soil layer. The bedrock subsidence is mainly related to mining height and bulking coefficient in TGZ, while it is mainly affected by mining height and distribution load on the key stratum in BPZ and CPZ. According to physical simulation and theoretical model, the maximum surface subsidence of No.1-2 seam mining in Ningtiaota coal mine are 1.1 m and 1.07 m respectively, which is basically consistence with the result of in-situ observation (1.2 m).

Reasonable Entry Layout of Lower Seam in Multi-Seam Mining Based on Numerical Simulation

2013 ◽  
Vol 295-298 ◽  
pp. 2980-2984
Author(s):  
Xiang Qian Wang ◽  
Da Fa Yin ◽  
Zhao Ning Gao ◽  
Qi Feng Zhao
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Coal Seam ◽  
Coal Mine ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Geological Conditions ◽  
Seam Mining

Based on the geological conditions of 6# coal seam and 8# coal seam in Xieqiao Coal Mine, to determine reasonable entry layout of lower seam in multi-seam mining, alternate internal entry layout, alternate exterior entry layout and overlapping entry layout were put forward and simulated by FLAC3D. Then stress distribution and displacement characteristics of surrounding rock were analyzed in the three ways of entry layout, leading to the conclusion that alternate internal entry layout is a better choice for multi-seam mining, for which makes the entry located in stress reduce zone and reduces the influence of abutment pressure of upper coal seam mining to a certain extent,. And the mining practice of Xieqiao Coal Mine tested the results, which will offer a beneficial reference for entry layout with similar geological conditions in multi-seam mining.

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.

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

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
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.

scholarly journals Mechanical Modeling of Roof Fracture Instability Mechanism and Its Control in Top-Coal Caving Mining under Thin Topsoil of Shallow Coal Seam

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Peilin Gong ◽  
Tong Zhao ◽  
Kaan Yetilmezsoy ◽  
Kang Yi
Keyword(s):  
Coal Seam ◽  
Mechanical Model ◽  
Main Roof ◽  
Stability Control ◽  
Hydraulic Support ◽  
Rock Stability ◽  
Shallow Coal Seam ◽  
Minimum Height ◽  
The Stability ◽  
Working Resistance

This study aimed to explore the safe and efficient top-coal caving mining under thin topsoil of shallow coal seam (SCS) and realize the optimization of hydraulic support. Numerical simulation and theoretical analysis were used to reveal the stress distribution of the topsoil, the structure characteristics of the main roof blocks, and the development of the roof subsidence convergence. Step subsidence of the initial fractured main roof after sliding destabilization frequently existed, which seriously threatened the safety of the hydraulic supports. Hence, a mechanical model of the main roof blocks, where the topsoil thickness was less than the minimum height of the unloading arch, was established, and the mechanical criterion of the stability was achieved. The working resistance of the hydraulic support was calculated, and the reasonable type was optimized so as to avoid crushing accident. Findings of the present analysis indicated that the hydraulic support optimization was mainly affected by fractured main roof blocks during the first weighting. According to the block stability mechanical model based on Mohr–Coulomb criterion, the required working resistance and the supporting intensity were determined as 4899 kN and 0.58 MPa, respectively. The ZZF5200/19/32S low-position top-coal caving hydraulic support was selected for the studied mine and support-surrounding rock stability control of thin-topsoil SCS could be achieved without crushing accident.

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