Estimate of the length of the plastic zone at the face of a coal seam being worked

1974 ◽  
Vol 10 (3) ◽  
pp. 272-276 ◽  
Author(s):  
N. S. Khapilova
Keyword(s):  
Plastic Zone ◽  
Coal Seam ◽  
The Face

Research on the Influence by Different Dip Angles Faults of the Damage Height of Superincumbent Stratum

2014 ◽  
Vol 675-677 ◽  
pp. 1421-1424 ◽  
Author(s):  
Zhen Li Fan
Keyword(s):  
Plastic Zone ◽  
Coal Seam ◽  
Small Angle ◽  
High Angle ◽  
Fractured Zone ◽  
Fault Surface ◽  
Influence Area ◽  
Wide Range

For the issue of fault impact on the height of water-flowing fractured zone, the study worked out several damage heights of superincumbent stratum under the influence of different dip angles faults. The research shows that small angle fault influence area is apt to develop a wide range of the plastic zone,and the water-flowing fractured zone of high-angle fault influence area is apt to increase along the fault surface and breakover the aquifers of coal seam roof and floor.

Numerical Analysis on Top Coal Caving of 2# Coal Seam in First Mine of Chagannaoer

2012 ◽  
Vol 594-597 ◽  
pp. 1338-1342
Author(s):  
Qing Hai Li ◽  
Ren Shu Yang ◽  
Wei Ping Shi
Keyword(s):  
Numerical Analysis ◽  
Plastic Zone ◽  
Coal Seam ◽  
Comprehensive Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Mining Technology ◽  
Geological Conditions ◽  
Numerical Software ◽  
Evolution Laws ◽  
Overlying Strata

In first mine of Chagannaoer, 2# coal seam, the mainly mined out layer, was 22.00m thickness in average. In order to meet the requirements of production ability, the mine was planned to apply mining technology of fully mechanized caving. Good or bad of top coal’s caving was an important prerequisite which decided the mining technology of top coal caving could be chosen or not. Due to lack of producing mines in this region and no experience to refer, we simulated the mining process of 2# coal seam using numerical software of FLAC3D, and gained evolution laws of stress and displacement of top coal and overlying strata and expansion laws of plastic zone. Through analysis, we got that the top coal damaged seriously and the top coal could be caved smoothly. Relying on the geological conditions of site, we verified the simulated results with method of fuzzy comprehensive evaluation. Combined with the research results, we decided that 2# coal seam’s caving was better and was convenient for top coal caving, so it was suitable for caving mining in 2# coal seam in first mine of Chagannaoer.

scholarly journals Roadway Surrounding Rock under Multi-Coal-Seam Mining: Deviatoric Stress Evolution and Control Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Dongdong Chen ◽  
En Wang ◽  
Shengrong Xie ◽  
Fulian He ◽  
Long Wang ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Coal Seam ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Deviatoric Stress ◽  
Mine Pressure ◽  
Coal Face ◽  
Surrounding Rock Control ◽  
Seam Mining ◽  
Peak Value

Multi-coal-seam mining creates surrounding rock control difficulties, because the mining of a coal face in one seam can affect coal faces in another. We examine the effects of multi-coal-seam mining on the evolution of the deviatoric stress distribution and plastic zone in the roadway surrounding rock. In particular, we use numerical simulation, theoretical calculation, drilling detection, and mine pressure observation to study the distribution and evolution characteristics of deviatoric stress on Tailgate 8709 in No. 11 coal seam in Jinhuagong mine when the N8707 and N8709 coal faces in No. 7-4 coal seam and the N8707 and N8709 coal faces in No. 11 coal seam are mined. The evolution laws of deviatoric stress and the plastic zone of roadway surrounding rock in the advance and behind sections of the coal face are studied, and a corresponding control technology is proposed. The results show that the peak value of deviatoric stress increases with the advance of the coal face, and the positions of the peak value of deviatoric stress and the plastic zone become deeper. The deflection angle of the peak stress after mining at each coal face and the characteristics of the peak zone of deviatoric stress and the plastic zone of the roadway surrounding rock under the disturbance of multi-coal-seam mining are determined. In conclusion, the damage range in the roadway roof in the solid-coal side and coal pillar is large and must be controlled. A combined support technology based on high-strength and high pretension anchor cables and truss anchor cables is proposed; long anchor cables are used to strengthen the support of the roadway roof in the solid-coal side and coal pillar. The accuracy of the calculated plastic zone range and the reliability of the combined support technology are verified through drilling detection and mine pressure observation on site. This research can provide a point of reference for roadway surrounding rock control under similar conditions.

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.

Optimization on Gateway Section of Soft Coal Seam and Hard Roof and Supporting Technology

2011 ◽  
Vol 90-93 ◽  
pp. 622-625
Author(s):  
Lu Chen ◽  
Chuan Wei Zang ◽  
Feng Hai Yu ◽  
Xiang Kun Yu
Keyword(s):  
Plastic Zone ◽  
Coal Seam ◽  
Field Application ◽  
Geological Condition ◽  
Hard Roof ◽  
Soft Coal ◽  
Production Safety ◽  
Geological Conditions ◽  
The Stability ◽  
Soft Coal Seam

Support invalidity of a roadway have a largely influence on production safety of coal mines, especially the soft coal roadway, which deforms heavily. To solve this problem, it began from the gateway section optimization, based on the actual geological condition of Chang-gouyu Mine. The computational model was established up to optimize tunnel shapes using FLAC3D. The scopes of plastic zone, stress field, displacement field were compared and analysed for different shapes of roadway. The irregular trapezoid section is adopted, then the bolt support parameters were designed and field application was done. By using the irregular trapezoid, the stress distribution around the roadway is improved and the deformation and plastic zone is decreased. Under the geological conditions of the soft coal seam and hard roof strata, the stability of roadway was effectively controlled by using optimized trapeziform cross-section and bolting support.

scholarly journals An Influence Study of Face Length Effect on Floor Stability under Water-Rock Coupling Action

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Baojie Fu ◽  
Bo Wang
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Mine Pressure ◽  
Length Effect ◽  
Pressure Relief ◽  
Limestone Aquifer ◽  
Study Results ◽  
Face Length ◽  
The Face ◽  
Floor Stability

The Taiyuan Formation limestone aquifer and Ordovician limestone aquifer are widely distributed in the coal seam floor of coal measures in North China; the water hazard safety problem of the stope floor under the influence of mining is very prominent. The risk of the water inrush from the coal seam floor is closely related to the degree of full exploitation, so it is necessary to study the stability of the stope floor under aquifer conditions, especially the influence of the working face length effect on floor stability. Through numerical simulation of water-rock coupling action, the mine pressure behaviors of the water-resisting floor under different face lengths were analyzed based on the measured formation permeability coefficient. The Fish program was used to adjust rocks entering the plastic failure state into a strain softening model to investigate the influence of the face length effect, the damage degree of the water-resisting floor, and the morphology and deformation bearing capacity of the failure zone. The results show the following: (1) the face length effect is one of the main influence factors of the failure mode and failure degree of surrounding rocks in the stope; (2) as the face length increases, the obvious pressure relief zone of surrounding rocks presents a staged change, and the obvious pressure relief zone at the seam roof and floor is in an obvious “reverse saddle shape”; (3) the closer to the seam floor, the more remarkable the rock softening characteristic because of the compaction action of gangues caving from the roof; and (4) the rock mass close to the seam floor undergoes local tensile failure, and the water-resisting floor near the coal wall at two sides mainly bears compaction-shear action, leading to compression-shear failure of the rock mass at the floor and formation of water-conducting fractures. The study results can provide a reference for taking precautionary measures of safety mining above a confined aquifer.

scholarly journals Field Investigation of Face Spall in Moderate Strength Coal Seam at Vang Danh Coal Mine, Vietnam

2021 ◽  
Vol 37 (2) ◽  
Author(s):  
Le Tien Dung ◽  
Dao Hong Quang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Main Roof ◽  
Field Investigation ◽  
Stability Control ◽  
Remedial Measures ◽  
Face Stability ◽  
Pressure Profiles ◽  
The Face ◽  
Leg Pressure

Face spall in moderate strength coal seam occurs less frequently but can be more severe and takes a longer time to remedy compared to face spall in the weak coal seam. This paper presents a field investigation of face spall in moderate strength coal seam at Face I-8-1, Vang Danh coal mine, Quang Ninh coal field, Vietnam. The leg pressure of shield support and face condition were monitored within two months, and on-site remedial measures to the spall were discussed. The monitoring results confirmed that the front and rear leg pressure profiles are consistent with world-wide observations. The coal face condition in actual operation was found to be more stable than that in project design. The face spall occurred along face dip direction, but mostly in small extent of less than 0.5 m deep and during transitional time between working shifts. Proper ground control near gate ends by using higher capacity shield supports and supplemental hydraulic props was identified to improve face stability in the area. On-site remedial measures proved their efficiency in small to moderate face spall extent. For main roof rupture-associated face spall, technical measures have been applied but they need further investigation to clarify their effectiveness. The paper’s results can be consulted to improve longwall face stability control in similar coal seam conditions.  

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