scholarly journals Gob-Side Entry Retaining Involving Bag Filling Material for Support Wall Construction

2020 ◽  
Vol 12 (16) ◽  
pp. 6353
Author(s):  
Zhaowen Du ◽  
Shaojie Chen ◽  
Junbiao Ma ◽  
Zhongping Guo ◽  
Dawei Yin
Keyword(s):  
Field Tests ◽  
Filling Material ◽  
Construction Technology ◽  
Working Face ◽  
Support Resistance ◽  
Pillar Mining ◽  
High Production ◽  
Wall Construction ◽  
Thin Seam ◽  
Seam Mining

Gob-side entry retaining, also termed as non-pillar mining, plays an important role in saving coal resources, high production and efficiency, extending the service life of mine and improving the investment benefit. Herein, a gob-side entry retaining method involving the use of bag filling material for wall construction is proposed based on the thin seam mining characteristics. First, a gob-side entry retaining mechanical model is established, and the side support resistance of the 8101 working face is calculated. The mechanical properties of the bag material are investigated through experiments, and the construction technology of the gob-side entry retaining approach involving the use of bag filling material for wall construction is introduced. The deformation on the two sides, the roof and floor of the roadway, are simulated via numerical methods and monitored during field tests. The results show a small control range for the deformations and a good roadway retention effect, thereby proving the feasibility of the bag filling material for wall construction. This study provides a reference for the development of gob-side entry retaining mining for thin coal seams.

scholarly journals Study on Surrounding Rock Structure Evolution Characteristics and Roof Control Techniques of the Retained Roadway Formed by Roof Cutting in Inclined Coal Seams

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Guangyuan Yu ◽  
Jiong Wang ◽  
Jianjun Ren ◽  
Jinzhu Hu ◽  
Zhifu Pan ◽  
...  
Keyword(s):  
Structure Evolution ◽  
Coal Seams ◽  
Supporting System ◽  
Working Face ◽  
Evolution Characteristics ◽  
Rock Structure ◽  
Support Resistance ◽  
Pillar Mining ◽  
Three Stages ◽  
Constant Support

To control the roof during gob-side entry retaining by roof cutting in inclined coal seams, the retained gob-side roadway is zoned based on the mechanical principle and technological process of no-pillar mining with gob-entry retention. A simplified mechanical model for surrounding rocks in different subzones was established by using theoretical analysis and numerical simulation to attain the demand for the support resistance and deformation of the roof in different subzones. According to load and deformation characteristics of the roof and mechanical characteristics of NPR cables, single props, and a sliding-type gangue-retaining structure formed by U-shaped steel inserts, the supporting systems for roadways in different subzones and the constitutive model thereof were established. On this basis, the action of the supporting system was analysed and a field test was performed. The results show that the supporting system undergoes three stages of behaviour, i.e., pressure growth, yielding under constant pressure, and stabilisation during whole entry retention. It can guarantee the collaborative deformation of the supporting systems with the roof on the premise of constant support resistance, thus satisfying the requirement for roadway protection. The roadway 150 m back from the working face is stable, and the final convergence between the roof and floor of the retained entry is 257 mm, showing a favourable entry-retention effect.

Study on the Supporting Method of Crossheading in Shallow-Buried Coal Seams Working Face Using FLAC Simulation

2013 ◽  
Vol 275-277 ◽  
pp. 1564-1568
Author(s):  
Jian Feng Luo
Keyword(s):  
Coal Mine ◽  
Field Tests ◽  
Reference Value ◽  
Working Face ◽  
Site Monitoring ◽  
Deformation Law ◽  
Before And After ◽  
Safety Production ◽  
Northern Shaanxi ◽  
Seam Mining

Taking 1403 coal face of Fengjia coal mine in northern Shaanxi as background, put forward three supporting schemes of crossheading according to different buried depth and coal seam interval. Applying FLAC software, established relevant calculating model, analyzed the stress field and surrounding rock deformation caused by shallow seam mining before and after supporting. Combining the result from site monitoring, obtained the deformation law of crossheading surrounding rocks in the short distance seam: the vertical deformation is the main deformation under the A support scheme. The field tests showed that: the supporting schemes according to the section of crossheading is feasible and it ensured haulage gate roadway’s surrounding rocks stability , met the requirements of safety production in the coal mine, the supporting schemes of crossheading proposed in this paper has reference value to similar project.

The Selection and Application of Filling Material Based on Long-Term Strength of Backfill Body

2011 ◽  
Vol 239-242 ◽  
pp. 3156-3160
Author(s):  
Bao Jie Fu ◽  
Min Tu
Keyword(s):  
High Stress ◽  
Filling Material ◽  
Term Strength ◽  
Exponential Relationship ◽  
Rock Body ◽  
Deep Mine ◽  
Long Term Stability ◽  
Working Face ◽  
Support Resistance

High stress makes backfill body present the rheological properties in deep mine. This paper first uses RRTS-ⅢA to carry on creep test of specimen in different proportion, according to ε-t curves under different load levels to determine the specimen’s long-term strength, based on the exponential relationship of rock block and rock body, the long-term compressive strength is derived, combining with concrete parameters of working face, mixture ratios of filling material which meet long-term stability are selected, while analyzing the support resistance of backfill body. The results show that this design can effectively avoid the rheological instability of backfill body.

scholarly journals Study on Three-Dimensional Stress Field of Gob-Side Entry Retaining by Roof Cutting without Pillar under Near-Group Coal Seam Mining

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 552 ◽  
Author(s):  
Xiaoming Sun ◽  
Yangyang Liu ◽  
Junwei Wang ◽  
Jiangbing Li ◽  
Shijie Sun ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Stress Field ◽  
High Stress ◽  
Peak Stress ◽  
Horizontal Stress ◽  
Surrounding Rock ◽  
Distribution Law ◽  
Working Face ◽  
Pillar Mining ◽  
Seam Mining

In order to explore the distribution law of stress field under the mining mode of gob-side entry retaining by roof cutting without pillar (GERRCP) under goaf, based on the engineering background of 8102 and 9101 working faces in Xiashanmao coal mine, the stress field distribution of GERRCP and traditional remaining pillar was studied by means of theoretical analysis and numerical simulation. The simulation results showed that: (1) in the front of the working face, the vertical peak stress of non-pillar mining was smaller than that of the remaining pillar mining, and it could effectively control stress concentration in surrounding rock of the mining roadway; the trend of horizontal stress distribution of the two was the same, and the area, span and peak stress of stress the rise zone were the largest in large pillar mining and the minimum in non-pillar mining. (2) On the left side of the working face, the vertical stress presented increasing-decreasing characteristics under non-pillar mining mode and saddle-shaped distribution characteristics under the remaining pillar mining mode respectively. Among them, the peak stress was the smallest under non-pillar mining, and compared with the mining of the large pillar and small pillar, non-pillar mining decreased by 12–21% and 3–10% respectively. The position of peak stress of the former was closer to the mining roadway, indicating that the width of the plastic zone of the surrounding rock of the non-pillar mining was smaller and bearing capacity was higher. In the mining of the large and small pillar, the horizontal stress formed a high stress concentration in the pillar and 9102 working face respectively. In non-pillar mining, the horizontal stress concentration appeared in solid coal, but the concentration area was small.

scholarly journals Application of High-Strength Lightweight Concrete in Gob-Side Entry Retaining in Inclined Coal Seam

2020 ◽  
Vol 2020 ◽  
pp. 1-20 ◽  
Author(s):  
Daoyong Zhu ◽  
Weili Gong ◽  
Yi Su ◽  
Aipeng Guo
Keyword(s):  
Performance Test ◽  
Lightweight Concrete ◽  
High Strength ◽  
Small Range ◽  
Optimal Arrangement ◽  
Working Face ◽  
Binder Ratio ◽  
Concrete Blocks ◽  
Support Resistance ◽  
Pillar Mining

Gob-side entry retaining (GSER) is a popular no-pillar mining technology that can increase coal recovery rate. We propose the application of high-strength lightweight (HSLW) concrete to construct the gob-side support body (GSSB) in NO. 411 inclined working face of Jingang Coal Mine. Firstly, the mechanical model of retained roadway was established, and the calculation for limit angle of GSSB stability and support resistance was mathematically derived. Using the performance test, the optimal proportion of LC50 concrete was determined as follows: the water-binder ratio was 0.3; the silica fume dosage was not more than 10%; the fly ash dosage was 10–20%; and the sand ratio was 0.45–0.50. Based on theoretical deduction and laboratory analysis, the width of GSSB was obtained to be 0.75 m, and the optimal arrangement of concrete blocks with “two longitudinal and one horizontal, crisscross, and staggered joints” was determined. FLAC3D software was used to study the influence of different widths and material strengths on the surrounding rock deformation and verify the reasonable width and strength of the designed GSSB. Finally, field monitoring of retained roadway shows that the deformation is controlled in a small range, and the retained roadway effect is better, thus proving the feasibility of HSLW for constructing the support body for GSER. Our findings can serve as a theoretical guide for safety and effective implementation of HSLW as GSSB.

The Application of Surrounding Rock Controlling Technology on Mining of Alluvium Coal Pillar

2011 ◽  
Vol 71-78 ◽  
pp. 2204-2209
Author(s):  
Zhong Sheng Bai
Keyword(s):  
Safety Management ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Construction Technology ◽  
Rock Support ◽  
Social Effectiveness ◽  
Working Face ◽  
Pillar Mining ◽  
Prevention And Cure ◽  
Constant Practice

In the alluvial coal pillar mining process, aiming at water prevention and cure, surrounding rock support, construction technology, safety management and the other main factors of safety mining, and through constant practice, the paper summarized the special measures of rock control on safety mining of alluvium coal pillar in the complex conditions for ensure safe of working face in alluvium corner coal, efficient mining, improve resource recovery. The economic and social effectiveness is remarkable.

The Optimization Research of Wide Strip and Full-Pillar Mining under Villages

2012 ◽  
Vol 616-618 ◽  
pp. 406-410
Author(s):  
Gui Liu ◽  
Hua Xing Zhang ◽  
Jin Hui Chen ◽  
Chao Gao
Keyword(s):  
Surface Structures ◽  
Strip Mining ◽  
Mining Method ◽  
Sequence Optimization ◽  
Wide Strip ◽  
Deformation Limit ◽  
Working Face ◽  
Specific Analysis ◽  
Pillar Mining ◽  
Coal Pillars

By making full use of the advantages of strip mining method and full-pillar mining method, the wide strip and full-pillar mining method can achieve the aim of mining under villages. However, at the full-pillar mining stage, the difficulty in managing several workfaces which are at work at the same time still exists. To improve the wide strip and full-pillar mining method’s applicability, an optimization of extraction sequence for coal pillars instead of the multi-working-face is put forward at the stage of full-pillar mining, and in the case of the deformation limit of surface structures is satisfied, to extract all the coal pillars which are under villages. By specific analysis of the extraction sequence optimization of the coal pillars in No.1 mine under Qian Xudapo village which belongs to Chang Chun coal Co., LTD., a better result is got which also acts a technological reference for the extraction under villages.

scholarly journals Study and Application of Roof Cutting Pressure Releasing Technology in Retracement Channel Roof of Halagou 12201 Working Face

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Ma Xingen ◽  
He Manchao ◽  
Wang Yajun ◽  
Zhang Yong ◽  
Zhang Jiabin ◽  
...  
Keyword(s):  
High Stress ◽  
Hydraulic Support ◽  
Working Face ◽  
Geological Conditions ◽  
Support Resistance ◽  
Cutting Effect ◽  
Mining Pressure ◽  
Cutting Height ◽  
First Time ◽  
Roof Deformation

The retracement channel roof cutting (RCRC) technology can change the overburden structure actively by cutting off the roof of channel along the direction of working face tendency and make use of the gangue collapsing from roof cutting range to fill the goaf and weaken the mining pressure during the retracement process of working face. In order to solve the problems of high stress in surrounding rock and serious deformation of retracement channel in Halagou coal mine, it is the first time that the pressure releasing test is carried out on the 12201 working face by the method of the directional presplitting roof cutting in retracement channel. First, according to statics theory and energy theory, the stress state of hydraulic support and roof deformation mechanism of retracement channel are analyzed. Then the roof cutting design of retracement channel is determined according to the geological conditions of 12201 working face, and the cutting effect is analyzed by numerical simulation. Finally, the field test is carried out on the 12201 working face to verify the effect of pressure releasing by roof cutting. The result shows that, with the roof cutting design including the roof cutting height being 8m and roof cutting angle being 45°, the roof subsidence of the 12201 working face retracement channel in Halagou mine is reduced to 132.5mm, and the hydraulic support resistance is maintained at 1361KN. And there is no hydraulic support crushed; the deformation of the retracement channel is also small; namely, the effect of roof cutting for pressure releasing is obvious.

scholarly journals A Mathematical Model and Error Analysis of Shearer Cutting Path Based on Its Attitude

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Shi-bo Wang ◽  
Shijia Wang ◽  
Zhaoliang Ge
Keyword(s):  
Mathematical Model ◽  
Error Analysis ◽  
Inertial Navigation System ◽  
Coordinate Frame ◽  
Medium Thickness ◽  
Position Errors ◽  
Working Face ◽  
Coordinate Position ◽  
Thin Seam ◽  
Cutting Path

The horizon control system is the key technology in the automation of a shearer. The achievement of accurate shearer cutting path plays an important role for horizon control. A mathematical model of cutting path in the local geographic coordinate frame was built. Error analysis based on genetic algorithm (GA) was studied to guarantee the accuracy of the shearer cutting path. Parameters from a MG1000/2660-WD shearer and data from a working face were used to obtain the shearer cutting path with reference to the local geographic coordinate frame. Also, with error analysis based on GA, the desired sensors were chosen, which allowed coordinate position errors of a shearer’s cutting path to be less than 0.01 m. The desired accuracies of the inertial navigation system and encoders mounted on the different shearers used in thin seam, medium-thickness seam, and thick seam were calculated.

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