scholarly journals Surrounding rock deformation and stress evolution in pre-driven longwall recovery rooms at the end of mining stage

2019 ◽  
Vol 6 (4) ◽  
pp. 536-546 ◽  
Author(s):  
Bonan Wang ◽  
Faning Dang ◽  
Wei Chao ◽  
Yanping Miao ◽  
Jun Li ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Recovery Room ◽  
Coal Pillar ◽  
Main Roof ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Stress Evolution ◽  
The Face ◽  
Surrounding Rock Deformation

Abstract Two case studies were conducted in the Shennan mining area of Shaanxi Province, China to evaluate the surrounding rock deformation and stress evolution in pre-driven longwall recovery rooms. These studies mainly monitored the surrounding rock deformation and coal pillar stress in the recovery rooms of the N1206 panel of 2−2 coal seam at Ningtiaota Coal Mine and the 15205 panel of 5−2 coal seam at Hongliulin Coal Mine. The monitoring results showed that the surrounding rock deformation of the main recovery room and the coal pillar stress in the N1206 and 15205 panels began to increase significantly when the face was 36 m and 42 m away from the terminal line, respectively. After the face entered the main recovery room, the maximum roof-to-floor convergence in the N1206 and 15205 panels was 348.03 mm and 771.24 mm, respectively, and the coal pillar stresses increased more than 5 MPa and 7 MPa, respectively. In addition, analysis of the periodic weighting data showed that the main roof break position of the N1206 and 15205 panels after the longwall face entered the main recovery room was − 3.8 m and − 8.2 m, respectively. This research shows that when the main roof breaks above the coal pillar, the surrounding rock deformation of the main recovery room and the coal pillar stress increase sharply. The last weighting is the key factor affecting the stability of the main recovery room and the coal pillar; main roof breaks at disadvantageous positions are the main cause of the support crushing accidents.

Surrounding Rock Convergence Rule along the Working Face Tendency of Recovery Room

2014 ◽  
Vol 962-965 ◽  
pp. 352-356
Author(s):  
Zhigang Wu ◽  
Wen Zhou Li
Keyword(s):  
Stress Distribution ◽  
Recovery Room ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Working Face ◽  
Deformation Mechanics ◽  
Surrounding Rock Deformation ◽  
Moving Speed

Recovery room could ensure the returning safety of working face equipment, improve mining and moving speed efficiency. Surrounding rock of working face will be distributed after recovery room driving, surrounding rock convergence drastically, and mining influence surrounding rock of recovery room also. Stress distribution around recovery room complex. Surrounding rock deformation rule along tendency of working face was studied by filed measurement in Sihe cola mine of the Jincheng coal district in China. It reveals surrounding rock deformation mechanics during coal pillar of working face through.

scholarly journals Surrounding rock deformation control of asymmetrical roadway in deep three-soft coal seam: a case study

2018 ◽  
Vol 15 (5) ◽  
pp. 1917-1928 ◽  
Author(s):  
Wei Zhang ◽  
Ziming He ◽  
Dongsheng Zhang ◽  
Dahong Qi ◽  
Weisheng Zhang
Keyword(s):  
Coal Seam ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Deformation Control ◽  
Soft Coal ◽  
Soft Coal Seam ◽  
Surrounding Rock Deformation

Control Technology and Application for Surrounding Rock Deformation in T-Junction Area of Gob-Side Entry Retaining

2013 ◽  
Vol 838-841 ◽  
pp. 1873-1879 ◽  
Author(s):  
Chang Liang Han ◽  
Nong Zhang ◽  
Bao Yu Li
Keyword(s):  
Abutment Pressure ◽  
Main Roof ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Control Technology ◽  
Support Design ◽  
Junction Area ◽  
Pressure Zone ◽  
Stress Zone ◽  
Surrounding Rock Deformation

On the bases of theoretic analysis, numerical simulation, and project practice, stress distribution of surrounding rock and movement characteristics of roof strata in T-junction area of gob-side entry were analyzed. Besides, control technology in T-junction area was proposed after indicating deformation characteristics of different stages in gob-side entry. Results show that there is an inclined block in T-junction area after fracture of main roof and the period when the block is tending to stability is a critical stage of pressure appearance for gob-side entry. Further, three stress zones: in-situ stress zone, abutment pressure zone and low stress zone appear in both strike and dip of mining panel and enhanced support of gob-side entry before excavation should keep away from the abutment pressure zone, which also indicates that deep bolting support can exert the bearing capacity of deep rock mass. Additionally, the whole procedure of surrounding rock deformation can be divided into four stages and deformation in gob-side entry is larger than that of entry excavation, which means that efficient support design should be taken into account. Ultimately, district control technologies for surrounding rock of gob-side entry in back zone, filling zone, and front zone are proposed and it showed a good adaption in project practice of coalmine.

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.  

The Numerical Simulation and Supporting Design of Gob-Side Entry Retaining in Gradient Medium Thick Coal Seam

2013 ◽  
Vol 368-370 ◽  
pp. 1812-1815 ◽  
Author(s):  
Yong Qin Zhang ◽  
Le Le Sun ◽  
Wei Zhong Zhang ◽  
Li Dan Cao
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Deformation Characteristics ◽  
Thick Coal Seam ◽  
Geological Conditions ◽  
Immediate Roof ◽  
The Impact ◽  
Surrounding Rock Deformation

In order to solve the technical problem of gob-side entry retaining in inclined coal seam, combined with the practical mining conditions in a certain mine, this paper adopts the discrete element method, applies numerical simulation to analyze inclined coal seam gob-side entry retaining with three different supporting ways, and studies surrounding rock deformation characteristics of gob-side entry retaining. The research results show that the filling body upper boundary for right side can control the roadway surrounding rock deformation better compared with the boundary is used as the hypotenuse; Meanwhile, the pressure of surrounding rock of coal seam gob-side entry retaining is mainly from the impact of the immediate roof natural fall of the upper goaf tilt and the weight of caving coal gangue and coal seam of immediate roof above; According to the surrounding rock deformation characteristics of coal seam remain gateway along goaf, it is determined to use combined supporting method of concrete filling in roadway sides and anchor wire rope supporting inside the roadways, providing the design basis of gob-side entry retaining in coal seam for the similar geological conditions.

scholarly journals Application of Distributed Optical Fiber Sensing Technology in Surrounding Rock Deformation Control of TBM-Excavated Coal Mine Roadway

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Bin Tang ◽  
Hua Cheng
Keyword(s):  
Optical Fiber ◽  
Coal Mine ◽  
Time Domain Reflectometry ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Deformation And Failure ◽  
Deformation Control ◽  
Monitoring Techniques ◽  
Deformation Behaviors ◽  
Surrounding Rock Deformation

After roadway excavation, the deformation and failure of roadway surrounding rocks typically results in roadway damage or collapse. Conventional monitoring techniques, such as extensometers, stress meters, and convergence stations, are only capable to detect the stress or strain data with the shallow layers of surrounding rocks, and they require arduous manual works. Moreover, in the abovementioned monitoring techniques, the monitoring instruments are installed behind the excavation face; therefore, the strain and deformation occurring in front of excavation face cannot be detected. In order to eliminate these shortcomings, an innovative monitoring system for surrounding rock deformation control has been developed base on Brillouin optical time domain reflectometry. Compared with conventional monitoring systems, the proposed system provides a reliable, accurate, and real-time monitoring measure for roadway surrounding rock deformation control over wide extension. The optical fiber sensors are installed in boreholes which are situated ahead of the excavation face; therefore, the sensors can be protected well and the surrounding rock deformation behaviors can be studied. The proposed system has been applied within a TBM-excavated roadway in Zhangji coal mine, China. The surrounding rock deformation behaviors have been detected accurately, and the monitoring results provided essential references for surrounding rock deformation control works.

scholarly journals Instability Analysis and Reinforcement Support Technology of Coal-Rock Interbed Roadway in Gaojiazhuang Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Chaolin Liu ◽  
Guohua Zhang
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Coal Mine ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Distribution Characteristics ◽  
Control Effect ◽  
Ultrasonic Detection ◽  
Wide Range ◽  
Surrounding Rock Deformation

In order to effectively solve a series of problems such as the difficulty of coal and rock interbed roadway support in Gaojiazhuang Coal Mine and get a scientific and reasonable optimization scheme of surrounding rock support, theoretical analysis, numerical simulation, ultrasonic detection, field-effect test, and other means are adopted to analyze the instability of coal and rock interbed roadway. The results show that the interbedded roadway has weak interbedded cementation, and its ore pressure is more intense due to the influence of its interbedded weak structural plane. Based on Mohr’s strength envelope principle, it is proposed that horizontal stress is the main factor that causes a wide range of shear displacement, penetration crack, and surrounding rock failure of the roof of this kind of roadway. Through the finite element numerical simulation analysis, the deformation and failure law, stress distribution characteristics, and failure area distribution characteristics of coal and rock interbedding roadway surrounding rock are theoretically revealed, and the control effect of different support schemes on roadway surrounding rock deformation is greatly different. Based on the ultrasonic detection technology, it is proved that the roadway side failure has strong zoning characteristics, and the failure range and stress distribution range of the surrounding rock of the belt roadway in the 2103 working face of Gaojiazhuang Coal Mine are detected. Finally, the coupling strengthening support scheme combining prestressed anchor cable and bolt is proposed. The engineering application and the observation of surrounding rock deformation show that the reinforced support technology can effectively enhance the stability of the surrounding rock of the interbed roadway in Gaojiazhuang Coal Mine, and it has a good reference for the surrounding rock conditions of this kind of roadway.

scholarly journals Research of the Surrounding Rock Deformation Control Technology in Roadway under Multiple Excavations and Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Ming Su ◽  
Xiaohui Gao
Keyword(s):  
Coal Mine ◽  
Reference Value ◽  
Field Investigation ◽  
Surrounding Rock ◽  
Rock Deformation ◽  
Control Effect ◽  
Deformation Control ◽  
Bolt Stress ◽  
Advanced Support ◽  
Surrounding Rock Deformation

To effectively control the large surrounding rock deformation of the mining roadway under multiple excavations and mining in Wangcun coal mine, the field investigation, numerical simulation, field test, and monitoring were conducted, and the characteristics of stress and deformation evolution of the surrounding rock under the influence of multiple excavations and mining were analyzed; then the collaborative supporting technology of high prestressed bolt and short anchor cables was proposed in this study. The results show the following: (1) under the influence of multiple excavations and mining, the peak vertical stress of the typical air-return roadway reaches 23 MPa, and the deformation increases by about 2.8 times after the mining of adjacent panel. (2) The principle of the roadway support under the influence of multiple excavations and mining in Wangcun coal mine is determined; from the perspective of prestress, we can conclude that the active support of short anchor cables is better than that of long anchor cables. (3) Based on the results of the field monitoring, the bolt stress can be divided into four stages: the loss stage of prestress, the sudden-decrease stage of the roof periodic weighting, the decrease stage of advanced support, and the rapid-increase stage of strong disturbance. Due to the large anchorage range of anchor cables, there is no decrease stage of advanced support. After the application of prestress, the bolt stress of side bolts and top bolts decreases, and the reduction amplitude is up to 30 kN. (4) As the panel advances, the deformation of the surrounding roadway increases, and the growth rate is also increasing gradually. However, the final displacement of the roof, floor, and two sides is within 18 mm. The bolt and anchor cables are not broken, and the control effect is good. The research results have a certain reference value for similar roadway control.

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