scholarly journals Migration Law of the Roof of a Composited Backfilling Longwall Face in a Steeply Dipping Coal Seam

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 188 ◽  
Author(s):  
Wenyu Lv ◽  
Yongping Wu ◽  
Liu Ming ◽  
Jianhui Yin
Keyword(s):  
Coal Seam ◽  
Inclination Angle ◽  
Mechanical Model ◽  
Surrounding Rock ◽  
Longwall Face ◽  
Mining Operations ◽  
Mining Depth ◽  
Working Face ◽  
Face Length ◽  
Migration Law

The artificial-caved rock composited backfilling approach can effectively restrain the dynamic phenomena in the coal seam and the associated roof and floor during mining operations, and can also improve the stability of the system of support and surrounding rock. In this study, based on the analysis of influencing factors affecting the surrounding rock movement and deformation of the composited backfilling longwall face in a steeply dipping coal seam, the roof mechanical model is developed, and the deflection differential equation is derived, to obtain the roof damage structure and the location of the roof fracture for the area without backfilling. The migration law of the roof under different inclination angles, mining depths, working face lengths, and backfilling ratios are analyzed. Finally, mine pressure is detected in the tested working face. Results show that the roof deflection, bending moment, and rotation drop with the increase of the inclination angle and backfilling ratio, whereas these parameters increase with greater mining depth and working face length. The roof failure location moves toward the upper area of the working face as the inclination angle and working face length increases, while it moves toward the center of the non-backfilling area with greater mining depth and backfilling ratio. Results from the proposed mechanical model agree well with the field test results, demonstrating the validity of the model, which can provide theoretical basis for a safe and efficient mining operation in steeply dipping coal seams.

Numerical Analysis of Influencing Factors of Stability in Thick Coal Seam Mining Roadway

2012 ◽  
Vol 256-259 ◽  
pp. 1453-1457
Author(s):  
Zhi Hua Li ◽  
Xin Zhu Hua ◽  
Ke Yang ◽  
Ruo Jun Zhu ◽  
De Sheng Zhou
Keyword(s):  
Coal Seam ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Rock Body ◽  
Thick Coal Seam ◽  
Mining Depth ◽  
Working Face ◽  
Face Length ◽  
Seam Mining ◽  
Mining Height

The FLAC-3D software was used to study the surrounding rock displacement and the side abutment pressure distribution laws about roadway in thick coal seam. Based on this model, through change the mining height, working face length and mining depth, the differences of roadway underground pressure characteristics were analyzed between thick coal seam working face and normal working face. The results indicate that: ①the displacement of roadway surrounding rock increases with the increase of mining depth and mining height, the closer to the coal wall the larger of the increase range of roadway displacement. ②the peak of side abutment pressure increases with the increase of mining depth and mining height, the peak district of the stress will move toward the inner department of rock body. ③ the effect of working face length on the roadway displacement and the side abutment pressure is very feeble.

Determination Method of the Supporting Intensity of Fully-Mechanized Face in Deeply Inclined Medium-Thickness Seam

2014 ◽  
Vol 522-524 ◽  
pp. 1386-1389
Author(s):  
Zhong Ping Guo ◽  
Hui Qiang Duan ◽  
Fan Feng ◽  
Gui Yin Zhang
Keyword(s):  
Coal Seam ◽  
Theoretical Basis ◽  
Surrounding Rock ◽  
Medium Thickness ◽  
Working Face ◽  
Displacement Thickness ◽  
Face Length ◽  
Working Resistance ◽  
Theory Calculation ◽  
The Relationship

According to the occurrence conditions of deeply inclined coal seam of 81206 working face in Yanya coal mine, methods including transmission rock theory calculation and numerical calculation based on the relationship between supports and surrounding rock are used to calculate and analyze. The proper working resistance of support is 5979.2kN and the supporting intensity is 0.8~0.95MPa. The regression equation associated with roof subsidence displacement , thickness of the coal seam, working face length and supporting intensity is accomplished, which provides theoretical basis for the support selection.

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.

scholarly journals Surrounding Rock Movement of Steeply Dipping Coal Seam Using Backfill Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Wenyu Lv ◽  
Kai Guo ◽  
Jianhao Yu ◽  
Xufeng Du ◽  
Kun Feng
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Surrounding Rock ◽  
Maximum Deflection ◽  
Coal Seams ◽  
Physical Similarity ◽  
Working Face ◽  
Rock Structure ◽  
Backfill Mining ◽  
The Stability

The movement of the overlying strata in steeply dipping coal seams is complex, and the deformation of roof rock beam is obvious. In general, the backfill mining method can improve the stability of the surrounding rock effectively. In this study, the 645 working face of the tested mine is used as a prototype to establish the mechanical model of the inclined roof beam using the sloping flexible shield support backfilling method in a steeply dipping coal seam, and the deflection equation is derived to obtain the roof damage structure and the maximum deflection position of the roof beam. Finally, numerical simulation and physical similarity simulation experiments are carried out to study the stability of the surrounding rock structure under backfilling mining in steeply dipping coal seams. The results show the following: (1) With the support of the gangue filling body, the inclined roof beam has smaller roof subsidence, and the maximum deflection position moves to the upper part of working face. (2) With the increase of the stope height, the stress and displacement field of the surrounding rock using the backfilling method show an asymmetrical distribution, the movement, deformation, and failure increase slowly, and the increase of the strain is relatively stable. Compared with the caving method, the range and degree of the surrounding rock disturbed by the mining stress are lower. The results of numerical simulation and physical similarity simulation experiment are generally consistent with the theoretically derived results. Overall, this study can provide theoretical basis for the safe and efficient production of steeply dipping coal seams.

scholarly journals Presplitting Blasting the Roof Strata to Control Large Deformation in the Deep Mine Roadway

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Chaowen Hu ◽  
Xiaojie Yang ◽  
Ruifeng Huang ◽  
Xingen Ma
Keyword(s):  
Large Deformation ◽  
Field Tests ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Deep Mine ◽  
Mining Depth ◽  
Working Face ◽  
Support Conditions ◽  
Mine Roadways ◽  
Roof Strata

As the mining depth increases, under the influence of high ground stress, the surrounding rock of deep mine roadways shows soft rock characteristics. Under the influence of mining disturbance at the working face, large deformation of the roadway has occurred. To control the large deformation of the roadway, many mines have adopted the form of combined support, which has continuously increased the support strength and achieved a certain effect. However, since the stress environment of the surrounding rock of the roadway has not been changed, large deformation of the roadway still occurs in many cases. Based on the theoretical basis of academician Manchao He’s “short cantilever beam by roof cutting,” this paper puts forward the plan of “presplitting blasting + combined support” to control the large deformation of the deep mine roadways. Without changing the original support conditions of the roadway, presplitting blasting the roof strata of the roadway, by cutting off the mechanical connection of the roof strata between the roadway and gob, improves the stress distribution of the roadway to control the large deformation. Through field tests, the results show that after presplitting blasting the roadway roof, the roadway roof subsidence is reduced by 47.9%, the ribs displacement is reduced by 45.7%, and the floor heave volume is reduced by 50.8%. The effect is significant.

Study on the Terminal Line Reasonable Position of Two Coal Seam under the Down-Protective Layer Pressure-Relieved Mining

2013 ◽  
Vol 295-298 ◽  
pp. 2913-2917
Author(s):  
Xiang Yang Zhang ◽  
Min Tu
Keyword(s):  
Coal Seam ◽  
Coal Pillar ◽  
Protective Layer ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Rock Properties ◽  
Engineering Practice ◽  
Working Face ◽  
Roadway Deformation ◽  
The Impact

In order to study the stress distribution and its dynamic influence law while the protective layer mining, based on the transfer law of mining-induced stress in the coal seam floor and in front of the working face, using numerical simulation software to simulate the surrounding rock stress under the different pillar width mining conditions, and carried through the roadway deformation engineering practice observations. It is shown that reserved 110m coal pillar could weaken the impact on the front of the floor tunnel under the protective layer mining process. When the top liberated layer mining to reduce the impact of mining stress superposition, it should avoid the terminal lines on the two coal seams at the same location and may be staggered at least about 30m ~ 50m. And it obtained that the roadway deformation not only by mining impact, but also considering the geological environment surrounding rock conditions, tunnel position in which layers of rock, rock properties and other factors. The research guided the engineering practice successfully.

scholarly journals Analysis of pressure relief and outburst prevention effect and mining depth effect of floor roadway in single serious outburst coal seam

2021 ◽  
Vol 267 ◽  
pp. 01051
Author(s):  
Guohong Chen
Keyword(s):  
Coal Seam ◽  
Field Test ◽  
Surrounding Rock ◽  
Test Results ◽  
Pressure Relief ◽  
Depth Effect ◽  
Mining Depth ◽  
Geological Conditions ◽  
Ground Stress ◽  
Outburst Coal Seam

In order to solve the serious problem of single serious outburst coal seam gas disaster, based on the gas geological conditions of Jiangxi Fengcheng Qujiang company, theoretical analysis, numerical simulation, field test and other comprehensive research methods were used to analyze the partition fracture law of roadway surrounding rock under different mining depth conditions. The results show that: under the conditions of high ground stress, high temperature and other environmental conditions, the radius of pressure relief loose circle of surrounding rock of roadway is significantly increased, and it is significantly larger than that of shallow part. In the deep area of - 800m elevation, the distance between floor roadway and coal seam is optimized to be 12 ~ 15m. The field test results show that the original permeability coefficient of overlying coal seam of floor roadway increases by 55.74 times, and the pressure relief effect is good.

Study on the Relationship between Hydraulic Support on the Working Face with Large Mining Height and Surrounding Rock

2011 ◽  
Vol 328-330 ◽  
pp. 1671-1674
Author(s):  
Ying Ma ◽  
Sheng Zhong
Keyword(s):  
Coal Seam ◽  
Surrounding Rock ◽  
Hydraulic Support ◽  
Working Face ◽  
Safety Work ◽  
Immediate Roof ◽  
The Face ◽  
Large Mining Height ◽  
The Relationship ◽  
Mining Height

Using unified model and theory of rock pressure, the problems, such as caving of stope roof with large mining height and destruction of support, strata movement and surface subsidence, are unified analyzed and researched. The results show that: pressure shell is dynamic shell, which moves forward with the propulsion of working face; with the increase of mining height on the face, the height of fracture zone in coal seam increases, not continuously, but jumpily; with the increase of mining height, support load rises, but the degree of this rise decreases gradually, increased degree of immediate roof weight should be greater than that of given deformation pressure. The results provide necessary basis for reliability of hydraulic support on the working face with large mining height and safety work in the underground.

scholarly journals Theoretical Calculation and Analysis on the Composite Rock-Bolt Bearing Structure in Burst-Prone Ground

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Liang Cheng ◽  
Yidong Zhang ◽  
Ming Ji ◽  
Mantang Cui ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Theoretical Calculation ◽  
Rock Burst ◽  
Mechanical Model ◽  
Surrounding Rock ◽  
Rock Bolt ◽  
Mining Engineering ◽  
Calculation Formula ◽  
Mining Depth ◽  
Rock Parameters ◽  
Bearing Structure

Given the increase in mining depth and intensity, tunnel failure as a result of rock burst has become an important issue in the field of mining engineering in China. Based on the Composite Rock-Bolt Bearing Structure, which is formed due to the interaction of the bolts driven into the surrounding rock, this paper analyzes a rock burst prevention mechanism, establishes a mechanical model in burst-prone ground, deduces the strength calculation formula of the Composite Rock-Bolt Bearing Structure in burst-prone ground, and confirms the rock burst prevention criterion of the Composite Rock-Bolt Bearing Structure. According to the rock burst prevention criterion, the amount of the influence on rock burst prevention ability from the surrounding rock parameters and bolt support parameters is discussed.

scholarly journals Experimental and Theoretical Investigation of Overburden Failure Law of Fully Mechanized Work Face in Steep Coal Seam

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Ze Liao ◽  
Tao Feng ◽  
Weijian Yu ◽  
Genshui Wu ◽  
Ke Li ◽  
...  
Keyword(s):  
Coal Seam ◽  
Mechanical Model ◽  
Hunan Province ◽  
Working Face ◽  
Overburden Failure ◽  
Geological Conditions ◽  
Fracture Area ◽  
Bending Fracture ◽  
Similar Simulation ◽  
Roof Deformation

In this study, both theoretical analysis and similar simulation experiment are employed to investigate the overburden failure law of fully mechanized face in the steep coal seam. By establishing the mechanical model of inclined rock beam, the deflection equation of overlying strata beam is obtained. Based on the geological conditions of Xiangyong coal mine in Hunan Province of China, the laws of roof deformation and failure in steep coal seam are obtained by similar simulation experiments. The results showed that the roof deformation of the goaf is relatively large after the working face advances along the strike, and the deformation mainly occurs in the upper roof of the goaf. The backward gangue in the immediate roof fills the lower part of the goaf, which plays a supporting role in the lower part of the roof and floor. The roof fracture of goaf is located in the middle and upper parts of the working face, which is consistent with the results derived from the mechanical model. After the roof fracture, a “trapezoid” bending fracture area and the secondary stability system area is formed, which is composed of four areas: the lower falling and filling support area, the upper strata bending fracture area, the fracture extension area, and the roof bending sinking area.

Sign in / Sign up

Export Citation Format

Share Document