scholarly journals The characteristics of mining induced stress fluctuations in broken rock mass over one kilometer deep coal mine

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 843-851
Author(s):  
Cong Li ◽  
Xiangang Yin ◽  
Jing Xie ◽  
Gaoyou Peng
Keyword(s):  
Fractal Dimensions ◽  
In Situ Monitoring ◽  
Mine Pressure ◽  
Deep Coal Mine ◽  
Working Face ◽  
Power Spectral ◽  
The Difference ◽  
Mining Face ◽  
Working Resistance ◽  
Hydraulic Supports

Mine pressure is critical to the safety of working face. Evaluating the working resistance accurately of the stope hydraulic supports is one of the most effective and direct ways to reflect the overall stress characteristics of the roof and the defor?mation, movement and destruction of overlying strata. Due to the complex breaking form of the roof, the working resistance of the hydraulic supports at different positions of the mining face varies in different ways. One can obtain the pressure of hydraulic support system by pressure monitoring and analyze its fractal characteristics. Through spectrum analysis, a new parameter called accumulation power spectral density is defined which is used to describe the difference of working resistance of stope hydraulic supports. The results show that the fractal dimensions of face-end supports are smaller and face-end supports are unco-ordinated. Through in-situ monitoring, it is found that the mining stress has unstable periodic fluctuation characteristics. The conclusion can provide reference for rational selection and optimization of the similar-mining lay-outs.

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 Study on the Mine Pressure Law and the Pressure Frame Mechanism of an Overlying Goaf in a Shallow Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Haifeng Zhou ◽  
Qingxiang Huang ◽  
Yingjie Liu ◽  
Yanpeng He
Keyword(s):  
Coal Pillar ◽  
Coal Extraction ◽  
Mine Pressure ◽  
Prevention Measures ◽  
Overburden Pressure ◽  
Load Pressure ◽  
Working Face ◽  
Coal Wall ◽  
Numerical Simulation Methods ◽  
Mining Face

To study the problems of dynamic load pressure and frame pressure caused by the concentration of stress by coal extraction pillars during the mechanized short-distance mining of goaves in shallow coal seams, a frame pressure accident, in the Shendong Shigetai Coal Mine, during the overlying of a fully mechanized mining goaf is taken as a research example. By applying the field measurement, theoretical analysis, and numerical simulation methods, we throughly analysed the working face coal pillar, got the regular pattern of fully mechanized overburden pressure, summarized a pillar of fully mechanized working face in the overburden strata movement regularity and development characteristics, analyzed the reason and mechanism of broken coal pillar, and put forward the corresponding prevention measures and management method. The results show that when the fully mechanized mining face enters the goaf by about 3 m, the pressure arches of the lower coal face and the upper goaf arising from the extracted coal overlap. When the vertical stress is greater than the supporting force of the hydraulic support and the coal wall, a roof ejection accident may occur.

Study on Pressure Regularity of the Fully Mechanized Coal Mining Face and Evaluation on Support Adaptability

2013 ◽  
Vol 734-737 ◽  
pp. 838-842
Author(s):  
Xing Shun Wang
Keyword(s):  
Theoretical Analysis ◽  
Coal Mining ◽  
Rock Pressure ◽  
Field Testing ◽  
Mine Pressure ◽  
Pressure Monitoring ◽  
Technical Parameters ◽  
Analysis And Evaluation ◽  
Working Face ◽  
Mining Face

Based on the theoretical analysis and field testing, for making clear of the roofs strata behaviors characteristics in the fully mechanized coal mining face in Hongliulin coal mine, and evaluating the adaptability of the support to the roof movement of the working face, this paper gives a collection analysis and evaluation of the rock pressure information during the working faces extraction to get the related technical parameters that can reflect the roof activity rule and the support adaptability analysis and meanwhile to provide some references for the mine pressure monitoring under the similar conditions.

Study on Mine Pressure Behavior of Roadway in Highly Irregular Working Face in Daizhuang Coal Mine

2012 ◽  
Vol 256-259 ◽  
pp. 1443-1446
Author(s):  
Xing Lin Wen ◽  
Lin Hai Gao ◽  
Chuan Lei Li ◽  
Meng Meng Dong
Keyword(s):  
Coal Mine ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Mining Engineering ◽  
Deformation Characteristics ◽  
Working Face ◽  
Production Safety ◽  
Support Force ◽  
Mining Face ◽  
Important Significance

The irregular face mechanized mining is one of the difficult problems in the field of mining engineering. In this thesis, the roadways of 4324 extremely irregular face in DaiZhuang Mine were taken as research object. Through on-site mine pressure observation, the deformation characteristics of the surrounding rock and support force was analyzed. Next the mine pressure appeared rule of the roadways was study. This study benefited that the production of 4324 mining face went on wheels, at the same time, it had important significance to production safety of irregular working face with similar conditions.

Characters Evaluation of Ground Pressure in Fully Mechanized Top Coal Caving Face in Soft Coal Seams

2011 ◽  
Vol 255-260 ◽  
pp. 3735-3739
Author(s):  
Wei Dong Pan ◽  
Xiao Hua Wu ◽  
Yang Li
Keyword(s):  
Coal Seam ◽  
Mining Area ◽  
Base Point ◽  
Coal Seams ◽  
Distribution Law ◽  
Soft Coal ◽  
Ground Pressure ◽  
Working Face ◽  
Working Resistance ◽  
Hydraulic Supports

Based on the big thickness, low stiffiness and other characters of No. 8 coal seam in Huaibei mining area, the moving laws of top coal seam and roof, and distribution law of ground pressure were studied under the fully mechanized top coal caving. The research methods included working resistance observation of hydraulic supports in working face, deformation observation of stope roadways and deeper base point observation in roof and top coal. The results show that, in the thick and soft coal seams, the influence coverage of mining ground pressure in fully mechanized top coal caving face is much wider than that in the working face with general mining technology, but the intensity of pressure is much lower.

Numerical Simulation of Gas Transportation in Mechanized Top-Coal Caving with Gob-Side Entry Retaining

2014 ◽  
Vol 577 ◽  
pp. 1170-1173
Author(s):  
Sheng Li ◽  
Jun Wen Li ◽  
Guang Yan Zheng ◽  
Nuo Nuo Ma
Keyword(s):  
Mass Conservation ◽  
In Situ Monitoring ◽  
Gas Migration ◽  
Thick Seam ◽  
Gas Concentration ◽  
Gas Accumulation ◽  
Working Face ◽  
Seepage Theory ◽  
Mining Face

To solve the problem of gas accumulation in thick-seam top-coal caving mining face, goaf gas migration equations were established based on seepage theory and the law of mass conservation. Taking No.7602 working face of Wuyang coal mine as the study object, gas migration rules of goaf in ventilation of U + I and Y+I were simulated by Fluent, and comparative analysis and verification were carried out by in-situ monitoring data. Test indicates that after gob-side entry retaining, average gas concentration value of No.7602 working face Return airway decreased by 39% compared with similar working face, decreased by 39% in gas emission roadway, decreased by 42% in upper corner. Ventilation of U + I can successfully resolve the problem of gas accumulation in upper corner and working face. The conclusion has a good instruction value to gas control in thick-seam top-coal caving mining face.

scholarly journals Effect of Face Length in Initial Mining Stage of Fully Mechanized Top-coal Caving Face With Large Mining Height

2021 ◽  
Author(s):  
Jianhang Wang ◽  
Yao Lu ◽  
CHANGXIANG WANG ◽  
Guangwei Xu ◽  
Chengran Zhang
Keyword(s):  
Mine Pressure ◽  
Pressure Behavior ◽  
Working Face ◽  
Face Length ◽  
The Face ◽  
Large Mining Height ◽  
Strata Behavior ◽  
Working Resistance ◽  
The Relationship ◽  
Surface Length

Abstract Based on the field measurement of the end resistance of the support during the initial weighting of the basic roof and the macroscopic mine pressure behavior during the weighting period of 101,22211,103 and 301 fully mechanized caving face in Changchun Xing Coal Mine, the mine pressure law of the working face is summarized and compared, and the relationship between the working face length and the working resistance of the support ( the weighting strength ) and the macroscopic mine pressure behavior is obtained. In the range of face length 126-230 m, with the increase of face length, the end-of-cycle resistance of the support gradually increases and the dynamic load coefficient of the support gradually increases when the coefficient of the support gradually increases, and the strata behavior of the working face changes from strong to very strong. When the face length is short ( 126-140.5m ), the hanging top area is too large to cause hurricanes when the working face is pressed, which threatens and damages the personal safety and equipment of the working face staff. Based on the above research, the problem of optimizing the surface length is proposed, and the surface length is determined to be within the range of 140-230 m according to the measured results.

scholarly journals Stability and Control of Retracement Channels in Thin Seam Working Faces with Soft Roof

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Binbin Qin ◽  
Fulian He ◽  
Xiaobing Zhang ◽  
Xuhui Xu ◽  
Wei Wang ◽  
...  
Keyword(s):  
Coal Mine ◽  
Main Roof ◽  
Field Application ◽  
Control Effect ◽  
Working Face ◽  
Safety Production ◽  
Thin Seam ◽  
Practice Methods ◽  
Working Resistance ◽  
Hydraulic Supports

To reduce the risk of roof falling and rib spalling during equipment retracement in thin coal seam faces with soft roofs, the 25070 working face of Xuehu Coal Mine was taken as the research object, and theoretical analysis, numerical simulation, and field practice methods were used. Under different space relationships between retracement channels and main roof fracture, the load of hydraulic supports was quantitatively analyzed. The relationship between the working resistance of the hydraulic support and the sinking rotation angle of the immediate roof was analyzed, and a reasonable time for the arrangement of the retracement channel was determined. The sublevel excavation technology and the combined support technology of roof anchor cables and coal rib anchors were proposed. The field application shows that the falling height and rate of movable prop of the hydraulic supports, working resistance of the hydraulic supports, and the roof subsidence all meet the requirements of safety production during the terminal mining period, and the surrounding rock control effect of retracement channel was determined to be good. The safe and efficient mining of the coal mine is ensured, and the research results can provide guidance for similar working faces.

Inflections of Periodicities of Background Photon Spectral Power Densities Are Predicted by the Lorentz Contraction for a Potential Indicator for the Intrinsic Structure of Space

2016 ◽  
pp. 4014-4017
Author(s):  
Michael A Persinger
Keyword(s):  
Spectral Power ◽  
Neutral Hydrogen ◽  
Intrinsic Structure ◽  
Lorentz Contraction ◽  
Intrinsic Nature ◽  
Basic Interval ◽  
Power Spectral ◽  
The Difference ◽  
Background Photon ◽  
Power Densities

                The value for the Lorentz contraction to produce a discrepancy for a hypothetical number that reflects a property (21.3π4) of sub-matter space was calculated. When applied to time the contraction would be ~35 min. The difference in mass-equivalent energy for an electron at c (the velocity of light in a vacuum) and the required v was ~2 ·10-20 J which has emerged as a significant quantity that may permeate from the force at Planck’s Length when applied across the wavelength of the neutral hydrogen line. Two separate types of photomultiplier instruments (digital and analogue) measuring with different sampling rates for background photon quantities over 50 randomly selected days demonstrated averaged conspicuous inflections of standardized spectral power densities around 35 min. This is the same basic interval where microvariations in the value of the gravitational constant (G) approached a limit at which white noise dominated.  The possibility is considered that this value for temporal inflections in photon power spectral densities may reflect the intrinsic nature of space-time contractions that relate gravity and photons.

scholarly journals Study on Fracture and Stress Evolution Characteristics of Ultra-Thick Hard Sandstone Roof in the Fully Mechanized Mining Face with Large Mining Height: A Case Study of Xiaojihan Coal Mine in Western China

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Feng Ju ◽  
Meng Xiao ◽  
Zequan He ◽  
Pai Ning ◽  
Peng Huang
Keyword(s):  
High Strength ◽  
Western China ◽  
Stress Evolution ◽  
Working Face ◽  
Mining Condition ◽  
Evolution Characteristics ◽  
Large Mining Height ◽  
Evolution Laws ◽  
Mining Face ◽  
Mining Height

Ultra-thick hard sandstone roofs present high thickness, poor delamination, and wide caving range. The strata pressure of the working face during actual mining increases, having a significant influence on the safe mining of the working face. Especially, in the mining areas of western China, the fully mechanized mining faces with high mining height and high-strength mining are more prominent. Understanding the fractures and stress evolution characteristics of the ultra-thick hard sandstone roof during actual mining is of high significance to control the dynamic pressure on the working face. In this paper, the typical ultra-thick hard sandstone roof of the Xiaojihan coal mine was taken as an example. The structural and chemical composition characteristics were analyzed. Besides, the fracture characteristics of ultra-thick hard roof during the working face mining were analyzed. Moreover, the fracture structure consistency was verified through physical simulation and a field measurement method. Finally, the stress evolution laws in the ultra-thick hard sandstone roof fracture were studied through numerical simulation. The findings demonstrated that (1) the ultra-thick hard sandstone roof was composed of inlaid coarse minerals, which had compact structure, while the Protodyakonov hardness reached up to 3.07; (2) under the high-strength mining condition of fully mechanized mining face with large mining height, the ultra-thick hard sandstone roof had the characteristics of brittle fracture, with a caving span of 12 m; (3) under the high-strength mining condition of fully mechanized mining face with large mining height, the ultra-thick hard sandstone roof followed the stress evolution laws that were more sensitive to the neighboring goaf. Therefore, it was necessary to reduce the fracture span or layering of ultra-thick hard sandstone roof through the manual intervention method adoption or increase either the strength of coal pillar or supporting body, to resist the impact generated during ultra-thick hard sandstone roof fracture.

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