retreat(ing) pillar mining with roof caving

2014 ◽  
pp. 1113-1113
Keyword(s):  
Roof Caving ◽  
Pillar Mining

scholarly journals Stability Analysis and Monitoring Method for the Key Block Structure of the Basic Roof of Noncoal Pillar Mining with Automatically Formed Gob-Side Entry

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Jianning Liu ◽  
Manchao He ◽  
Yajun Wang ◽  
Ruifeng Huang ◽  
Jun Yang ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Coal Mine ◽  
Block Structure ◽  
Monitoring Method ◽  
Roof Caving ◽  
Pillar Mining ◽  
Key Block ◽  
The Stability ◽  
Block Structures ◽  
Basic Roof

The key block of the basic roof is the main contributor to the structural stability of a roadway. Research on the stability of the key block structure is of great significance for the promotion of noncoal pillar mining with automatically formed gob-side entry (GEFANM) technology. This paper is set in the engineering context of the GEFANM experiment at the Ningtiaota Coal Mine. The study fully considered the differences in the gob roof caving on the roof-cutting-line side, and the range of rotation angles to maintain a stable key block was determined. Based on this range of rotation angles, the range of safe bulking coefficients of gangue was calculated. The bulking coefficient of the gangue on the gravel side of the roadway was used as the metric in a new monitoring method and in the calculation of the field parameters. The range of safe bulking coefficients was determined to be 1.40–1.37. Field monitoring was conducted to obtain the gangue bulking coefficient on the gravel side. Combining the roof and floor convergence data, when the bulking coefficient fell within the safe range, the convergence was 95–113 mm. In this stage, the key block structure was stable. When the gangue bulking coefficient fell outside the safe range, the convergence was larger, and cracks were observed. The key block may be vulnerable to instability. The results affirmed that the gangue bulking coefficient can be used as a monitoring metric to study the stability of key block structures.

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.

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