Pressure-Arching Characteristics in Roof Blocks during Shallow Coal Mining

To reveal the performance of the stepped subsidence and the strong roof weighting during shallow coal mining, taking the fully mechanized mining face with large mining height in the Shendong mining area in China as the engineering background, theoretical analysis and numerical simulation were used to analyze the pressure-arching effect of the hanging roof blocks. Three typical pressure-arch models of the roof structure were proposed, such as the symmetrical pressure-arch of two key blocks, the step pressure-arch of multiple key blocks, and the rotative pressure-arch of multiple key blocks. Results indicate that the horizontal stress displays a nonlinear distribution at the abutments of the symmetrical pressure-arch, and there is a linear distribution of horizontal stress with a higher peak value at the midspan of the pressure-arch. The high horizontal stress at the arch abutment is necessary to form the rotative pressure-arch of multiple key blocks. The horizontal stress is relatively less at the arch abutment of the step pressure-arch structure. The main key block is easier to slide in this structure as the boundary horizontal stresses display the nonlinear distribution. The results are of instructive significance for roof weighting forecast and strata control during shallow horizontal mining for a thick coal seam.

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Study on the Law of Surface Cracks While Coal Mining in the Thin Bedrock and Thick Unconsolidated Layer of Yu-Shen-Fu Mining Area

E3S Web of Conferences ◽

10.1051/e3sconf/20185303040 ◽

2018 ◽

Vol 53 ◽

pp. 03040

Author(s):

Wu Zuoqi ◽

Wang Guoku ◽

Zhao Liqin

Keyword(s):

Coal Mining ◽

Ground Surface ◽

Mining Area ◽

Dynamic Evolution ◽

Surface Cracks ◽

Whole Process ◽

Thin Bedrock ◽

The Law ◽

Mining Face ◽

Overlying Strata

The law of surface cracks caused by coal mining in ther thin bedrock and thick unconsolidated layer was studied in Yu-Shen-Fu mining area. The crack development in the overlying strata of the coal mining face was detected by drilling survey technology, the whole process of the ground surface crack dynamic evolution was carried out by similar material simulation, and the law of surface cracks evolution was verified by on-site tracking measurement. The study reached the regulation of the overlying strata failure and dynamic evolution of surface cracks caused by coal mining under thin bedrock and thick unconsolidated layer in Yu-Shen-Fu mining area, which can provide theoretical support for the ecological restoration of western mining area.

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Research on the Overlying Strata in Full-Mechanized Coal Mining of Datong Jurassic Coal Multi-Layer Goaf

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.616-618.402 ◽

2012 ◽

Vol 616-618 ◽

pp. 402-405 ◽

Cited By ~ 1

Author(s):

Hong Chun Xia ◽

Guo Sheng Gao ◽

Bin Yu

Keyword(s):

Coal Seam ◽

Coal Mining ◽

Coal Pillar ◽

Mining Area ◽

Mechanics Model ◽

Roof Structure ◽

Geological Conditions ◽

Seam Mining ◽

The Impact ◽

Overlying Strata

According to the specific geological conditions in themulti-layer worked-out areas of Yongding coal seam, by the methods of integration of theoretic analysis, numerical value calculation and so on, we studied movement law of Overlaying Strata and influence of coal pillar in Coal seam mining, obtained the basic law of the overlying strata movement in multiplayer, provides a theoretical basis for the safe and efficient exploitation of the success of multiplayer. Many mining area in China is mining of closed distance coal seam group, By the impact of coal seam in the overlying, face and the tunnel roof structure will be different injury in sub-coal seam mining, Roof structure has changed greatly, even damage and easily take the roof leakage, When the the goaf communication with the overlying coal seams, caused by the induced secondary disasters such as face air leakage, Therefore, exploitation of the law of motion of the overlying strata in the multiplayer is a pressing problem. Exploitation multiplayer seam few theoretical and technical foundation at home and abroad, affecting the validity of the mining, rationality. although a lot of research on theory and technology of coal mining over the years[1~5], But it was not able to an overall comprehensive analysis of upper goaf adjacent goaf and overlying the coal pillar and present mining face, create a dynamic structural mechanics model, which is likely to cause the occurrence of disasters.

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Microseismic Monitoring and Numerical Simulation Research of Floor Failure Depth in Extra-Thick Coal Seam

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.881-883.1799 ◽

2014 ◽

Vol 881-883 ◽

pp. 1799-1804 ◽

Cited By ~ 1

Author(s):

Ai Ping Cheng ◽

Yong Tao Gao ◽

Chao Liu ◽

Jin Fei Chai

Keyword(s):

Numerical Analysis ◽

Coal Mining ◽

Microseismic Monitoring ◽

Floor Rock ◽

Thick Coal Seam ◽

Floor Failure ◽

Mining Disturbance ◽

Microseismic Events ◽

Mining Face ◽

Failure Depth

Based on the condition of fully mechanized caving face in one mine, two methods of microseismic monitoring and numerical analysis were combined to study the evolution characteristics and development law of floor failure depth in extra-thick coal seam. Microseismic monitoring results show that the number of microseismic events partly reflects the influence of mining disturbance in the roof and floor rock mass. The distribution of microseismic events are intensive near the coal mining face, which show the floor rock mass is seriously damaged during the coal mining. The greatest floor failure depth estimated from mine microseismic monitoring is 31 meters. Numerical analysis indicate that the rock stress around the mine stope is redistributed during the coal mining, due to the effect of mining disturbance. The abutment pressure increases in front of the coal mining face and the stress reduces in the mined areas. The concentration and release of the stress makes contribution to the destroy of the floor rock. The maximum floor failure depth is up to 28 meters calculated from numerical simulation. The consistency of microseismic monitoring results and numerical analysis improve that it is effective and reliable to obtain floor failure depth and considerably possible to predict the water inrush using microseismic monitoring technology with its inherent ability to remotely monitor the progressive failure caused by mining. The research results have great popularization and application values for the similar mine.

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Roadway Supporting Technology in Fully Mechanized Workface with Large Mining Height of Specially Thick Coal Seam in Datong Mining Area

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.204-208.1611 ◽

2012 ◽

Vol 204-208 ◽

pp. 1611-1616 ◽

Cited By ~ 3

Author(s):

Guo Liang Lu ◽

Chen Wang ◽

Yao Dong Jiang ◽

Hong Wei Wang

Keyword(s):

Coal Seam ◽

High Reliability ◽

Soft Rock ◽

High Strength ◽

Mining Area ◽

Thick Coal Seam ◽

Roadway Safety ◽

Large Mining Height ◽

Soft Rock Roadway ◽

Mining Height

Aimed at the supporting problems in the fully mechanized roadway with large mining height of the specially thick coal seam in workface 8105 in Tashan coal mine, the “three highs with one low” supporting technology of high strength, high stiffness, high reliability and low support density was adopted to solve the roadway supporting problems of specially high coal side and specially large section and effectively control the surrounding rock deformation and ensure the roadway safety. It also increased the roadway excavation speed which made good conditions for fast advance of the fully mechanized workface, and it made the soft-rock roadway supporting technology in Datong mine area develop into a new level.

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A Mechanical Analysis of Support Instability Risk along the Strike of Coalface in Thick Coal Seam with Large Dip Angle: A Case Study

Earth Sciences Research Journal ◽

10.15446/esrj.v25n1.74167 ◽

2021 ◽

Vol 25 (1) ◽

pp. 101-108

Author(s):

Wei Zhang ◽

Weisheng Zhang ◽

Dongsheng Zhang ◽

Dahong Qi ◽

Ziming He

Keyword(s):

High Efficiency ◽

Mining Area ◽

Mechanical Analysis ◽

Thick Coal Seam ◽

Technical Parameters ◽

Geological Conditions ◽

Mechanical Models ◽

Large Mining Height ◽

Dip Angle ◽

Working Resistance

To ensure safe and high-efficiency mining in the coalface with large dip angle (LDA) and large mining height (LMH), it is important to study the support stability of the coalface under the corresponding conditions. This study is based on the #3up509 coalface of the Gaozhuang Coal Mine (GCM) affiliated with the Zaozhuang Mining Area (ZMA), for which the mechanical characteristics of support in the coalface with LDA and LMH are analyzed. On this basis, the mechanical models for support tilting and sliding in the coalface are developed. Then support stability along the strike of the coalface during the normal mining period (NMP) and special mining period (SMP) is analyzed. The results show that the critical support tilting resistance during the NMP is 52.2 kN, and the critical support sliding resistance is 183.75 kN, and for the SMP, the values are 2679 kN and 4425 kN, respectively. The use of a two-leg shield support, known as ZY6600-25.5/55 (its rated working resistance is 6600 kN), is investigated, which is proved reasonable for the coalface. The influencing factors of support stability along the strike include technical parameters of the support, mining geological conditions of the coalface and specific conditions during mining. Technical measures, such as installing interlock set to fasten support and adjustable lifting jack, increasing the setting load of the support, and optimizing the support displacement method, are taken to increase the overall support stability in the coalface. The initial aim for a safe and high-efficiency mining at the #3up509 coalface has been achieved through the aforementioned measures.

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