scholarly journals Simulation Research for the Influence of Mining Sequence on Coal Pillar Stability under Highwall Mining Method

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jing Huang ◽  
Fanbao Meng ◽  
Ge Wang ◽  
Yingkui Wu ◽  
Jinhao Wen
Keyword(s):  
Great Influence ◽  
Coal Pillar ◽  
Simulation Method ◽  
Mining Method ◽  
Pillar Stability ◽  
Simulation Research ◽  
Highwall Mining ◽  
Mining Sequence ◽  
Coal Pillars ◽  
Highwall Stability

Highwall mining, which is referred to the technique of extracting coal from the bottom of an exposed highwall, features safety, efficiency, and economy. According to existing highwall mining methods, the mining sequence has a great influence on highwall stability. Based on a highwall mining project in Australia, this study adopted the FLAC3D numerical simulation method to investigate the stability of coal pillars with different mining sequences. The results show that different mining sequences of boreholes exert a great effect on highwall stability. Compared with sequential mining, the skip mining method achieves higher speed of highwall stabilization and smaller plastic zone of coal pillar with its maximum strength decreasing by 12%. By adjusting the mining sequence scientifically, the coal pillar failure and roof collapse caused by the deviation of mining angle can be avoided. The results may provide a new angle for the studies on the coal pillar layout and stability design in highwall mining.

Modeling and Numerical Optimal Simulation of Coal Pillar’s Failure Process on Longwall Leaving Coal Pillar Mining

2011 ◽  
Vol 88-89 ◽  
pp. 285-290 ◽  
Author(s):  
Xiao Ping Shao ◽  
Yu Cheng Xia
Keyword(s):  
Optimization Design ◽  
Design Research ◽  
Failure Process ◽  
Coal Pillar ◽  
Shaanxi Province ◽  
Mining Method ◽  
Pillar Stability ◽  
Plastic Failure ◽  
Mining Methods ◽  
Coal Pillars

To further optimize mining methods and parameters at regions of “protecting water mining”, this paper has made modeling and numerical optimal simulation of coal pillar’s failure process under two kinds of mining method including “taking 8 remaining 7” leaving the region pillars and “taking 12 remaining 8” leaving strip coal pillars for Yubojie coal mine in northern Shaanxi province in China. Simulation showed that the stability of strip coal pillars is better than the region coal pillars at the same advancing distance. The region coal pillars first appeared corner plastic failure and maybe become hexagonal pillars. Plastic failure of the rectangular pillar extended and penetrated from the corner along the edge. Plastic damage of pillars showed tendency from the middle to the roadway side of the face along the length direction of face. Stability of central elastic core of coal pillar is the basis of pillar stability. Simulation results showed that it is feasible to optimize mining methods and parameters of “protecting water mining" areas based on modeling and numerical simulation of pillar failure process. The method has provided a useful reference to mining method and optimization design research for other regions with same type of domestic and international coal mines.

scholarly journals The Influence of the Backfilling Roadway Driving Sequence on the Rockburst Risk of a Coal Pillar Based on an Energy Density Criterion

2018 ◽  
Vol 10 (8) ◽  
pp. 2609 ◽  
Author(s):  
Yi Xue ◽  
Zhengzheng Cao ◽  
Feng Du ◽  
Lin Zhu
Keyword(s):  
Energy Density ◽  
Dynamic Instability ◽  
Coal Pillar ◽  
Optimal Choice ◽  
Mining Technology ◽  
Pillar Stability ◽  
Rockburst Hazard ◽  
Density Factor ◽  
Coal Pillars ◽  
Energy Density Factor

The rockburst hazard has always been an important issue affecting the safety production of coal mines in China. The unreasonable sequencing of roadway driving can lead to the dynamic instability of coal pillars, which subsequently causes rockburst accidents in roadway backfilling mining engineering and poses a serious threat to the safety of the mines. Roadway backfilling mining technology is an effective approach with which to mine corner residual coal resources under buildings, railways, and rivers. An energy density criterion is established and programmed with FISH language using numerical analysis software for the rockburst risk evaluation of coal pillars. On this basis, a numerical simulation model is established based on four scheme types, namely, the sequential mining, one-roadway interval mining, two-roadway interval mining, and three-roadway interval mining schemes. The influence of the backfilling roadway driving sequence on coal pillar stability is investigated, and the change law of vertical stress and energy density factor of coal pillars in different driving sequences in roadway backfilling mining technology are analyzed. According to the research results, the maximum energy density factor value of 21,172 J/m4 for coal pillars in one-roadway interval mining is the lowest among the different schemes. Therefore, the one-roadway interval mining scheme is the optimal choice in roadway backfilling mining technology. The results can be treated as an important basis for the prevention and treatment of coal pillar instability and rockburst in roadway backfilling mining technology.

Research of New Filling and Mining Technology Using Waste Rocks in Steep Coal Seams

2012 ◽  
Vol 204-208 ◽  
pp. 1395-1400
Author(s):  
Chuan Wei Zang ◽  
Chuan Le Ma ◽  
Xue An Zhuang
Keyword(s):  
Coal Mining ◽  
Coal Pillar ◽  
Recovery Ratio ◽  
Mining Method ◽  
Coal Seams ◽  
Coal Recovery ◽  
Waste Rocks ◽  
Filling Method ◽  
Gob Area ◽  
Coal Pillars

During the extraction of steeply inclined coal seams, the coal recovery ratio is low be-cause of the coal pillar loss and the production of waste rock is high due to lots of rock roadways which causes serious environmental pollution. This status is conflicted with the strategy of Clean Coal Mining and Green Coal Mining in China, so it is necessary to develop new coal mining method. In this paper, Downward Stratified Gangue Self-filling Method on the Flexible Shield (DSGSMFS) is put forward first. It means that the coal face is lain horizontally and advances along the dip; the flexible shield is used to separate the gob area; the waste rocks are self-filled downward to the top the shield; the coal is broken by drilling and blasting method under the shield, and the broken coal is transported by the electrical winch and the scraping mucker; the flexible shield moves downward automatically by the weight of itself and waste rocks. Field test shows that the strata displacement is effectively controlled by using DSGSMFS, so some coal pillars are recovered; as a result the problem of large quantity gangue and low coal recovery ratio in steep coal seam is solved. DSGSMFS is proved to be a new hopeful and effective coal green mining method.

scholarly journals Simulation Analysis and Engineering Application of Retaining Width of Waterproof Coal Pillar in Island Working Face

2021 ◽  
Author(s):  
Lili Zheng ◽  
Zheng Gao
Keyword(s):  
Service Life ◽  
Simulation Analysis ◽  
Engineering Application ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Simulation Research ◽  
Working Face ◽  
Before And After ◽  
Mining Face ◽  
Coal Pillars

The old mining area in Pingdingshan coalfield has the following problems: long mining service life, many remaining coal pillars, and great difficulty in mining; to extend the service life of the mine, realize cost saving and efficiency increasing, it is urgent to recover the remaining coal pillars, but the mining of isolated island face faces the problem of reasonable retention of waterproof coal pillars, if the protection is not good, it is easy to cause mine water damage and increase the mining cost. Therefore, in view of the practical engineering problems faced by the field, aiming at eliminating or reducing the goaf water disaster, this paper adopts numerical simulation research methods to optimize the original design scheme and carry out comparative analysis, dynamically reappear the surrounding rock stress field, displacement field and plastic failure law under multi face mining and roadway mining, and carry out engineering practice application. The results show that there is a certain thickness of elastic core area before and after mining with 25m coal pillar width. The deformation of surrounding rock is small, which is conducive to roadway maintenance, without obvious stress concentration. It can meet the actual needs of the project. The mining face has achieved safe mining, without water inrush accident in the goaf, and the coal resources have been recovered to the maximum extent. The research results are left over to similar mining areas in China The safe recovery of coal pillar can be used for reference.

scholarly journals Improvement of the Loading Capacity of Narrow Coal Pillars and Control Roadway Deformation in the Longwall Mining System. A Case Study at Khe Cham Coal Mine (Vietnam)

2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Le QUANG PHUC ◽  
V. P. ZUBOV ◽  
Phung MANH DAC
Keyword(s):  
Longwall Mining ◽  
Coal Pillar ◽  
Rock Bolt ◽  
Mining System ◽  
Pillar Stability ◽  
Roadway Support ◽  
Coal Pillars ◽  
The Stability ◽  
Safe Condition ◽  
Cable Bolt

Currently, the application of coal pillars to protect an adjacent roadway is a common method in Vietnam when exploiting according to the longwall system. Therefore, the width of a coal pillar is an important issue for the stability of a roadway. In order to reduce coal loss in these coal pillars, they tend to be designed in a narrow coal pillar style but still have to ensure that the adjacent roadway can meet safe coal production conditions. The stability of roadways and coal pillars is related to many factors such as technical mechanical characteristics, physical and mechanical properties of coal, stress environment and support methods. The bearing structure of the coal pillar and the around rock a roadway is analyzed and it has been shown that enhancing roadway support and improving the carrying capacity of coal pillars can control the deformation of the surrounding rock. A study related to the stability and safety of roadways and small coal pillars in the longwall mining system has been carried out. Stabilization factors have been considered, especially the state of stress in the coal pillars and the deformation of the roadway. By applying the numerical simulation method, the stress of the coal pillar and the deformation of the adjacent roadway under different supporting solutions were analyzed and evaluated. By using this method, the rock bolt roadway support solution combined with the long cable bolt in the roadway roof and the coal pillar was selected in the safe condition of the mining process. Because cable bolt can improve the flexibility of the coal pillar such as: reducing the size of the plastic area on both sides of the pillar; enhancing coal pillar stability in the core area by providing great drag and tensile for coal pillars; contributing to improving the anchor point fixation of rock bolt. The conclusions obtained may provide a certain reference parameters to improve mining efficiency and labor safety in underground coal mines.

Research on the Design for Strip-Partial Mining Method under Villages at Xiaotun Colliery

2011 ◽  
Vol 361-363 ◽  
pp. 217-221 ◽  
Author(s):  
Rui Min Feng ◽  
Jin Long Zhang ◽  
Hui Fu ◽  
Lei Pei
Keyword(s):  
Numerical Simulation ◽  
Simulation Analysis ◽  
Coal Pillar ◽  
Field Measurements ◽  
Mining Method ◽  
Pillar Stability ◽  
Surface Movement ◽  
Mining Condition ◽  
Movement And Deformation ◽  
Mining Scheme

Basing on the geological mining condition under villages at Xiaotun Mine, according to the existing theories of the strip-partial mining, using the method of analyzing the field measurements date and calculating by empirical formula, the safe range of mining and retained widths can be confirmed, the mining schemes for different widths of coal pillar can be designed, and the optimum scheme can be worked out; and then the coal pillar stability of each mining scheme will be calculated through numerical simulation analysis, providing the basis for appropriately selecting the optimum scheme; on this basis, through simulation prediction of the surface movement and deformation, the surface movement and deformation laws of strip-partial mining is revealed to guide production of Xiaotun colliery.

scholarly journals Study on Web Pillar Stability  in Open-Pit Highwall Mining

2021 ◽  
Author(s):  
Juyu Jiang ◽  
Zhuowei Zhang ◽  
Dong Wang ◽  
Laigui Wang ◽  
Xinping Han
Keyword(s):  
Ultimate Strength ◽  
Coal Pillar ◽  
Open Pit ◽  
Instability Criterion ◽  
Pillar Width ◽  
Mining Technology ◽  
Pillar Stability ◽  
Yield Zone ◽  
Highwall Mining ◽  
The Web

Abstract When highwall mining technology is applied to recover large amounts of residual coal left under the highwall of a big open-pit mine, reasonable coal pillar width is the premise for maintaining the stability of web pillars. By adopting the numerical simulation method, the characteristics of the abutment stress distributions in the web pillars under different slope angles and mining depths are studied, and the function of the stress distribution in the web pillar is established. The relationship between the abutment stress and the ultimate strength of the web pillar under different widths is also analyzed and used in combination with the failure characteristics of the pillar yield zone to explore the instability mechanism of the web pillar. The retaining widths of the web pillars are determined. Based on the modeling results, a mechanical bearing model of the web pillar is established, a cusp catastrophe model of pillar-overburden is constructed, and the formula for the web pillar instability criterion is obtained. By analyzing and calculating the ultimate strength of the web pillar, the formula for calculating the yield zone width at both sides of the pillar is achieved. Using the instability criterion of web pillars in highwall mining, a reasonable pillar width can be deduced theoretically, which provides significant guidance on the application of highwall mining technology.

Design and simulation research of the double-spin folding mechanism based on a suspended missile

2021 ◽  
pp. 154851292110231
Author(s):  
ZH Yuan ◽  
SY Guo ◽  
SN Zhang ◽  
JQ Zhao ◽  
WJ Lu ◽  
...  
Keyword(s):  
High Reliability ◽  
Lift Coefficient ◽  
Great Influence ◽  
Reference Value ◽  
Aerodynamic Characteristics ◽  
Simulation Software ◽  
Fluid Simulation ◽  
Simulation Research ◽  
Double Spin ◽  
Locking Mechanism

Based on the suspension of a missile using folding rotary wings and airbags, in order to improve the basic parameters and motion characteristics of the rotor during the unfolding process and analyze the aerodynamic characteristics of the entire device in the suspension state, after proposing a scheme of double-spin mechanism, the main folding and unfolding mechanism, initial driving device, rotating driving device, and locking mechanism were designed, and the simulation research is studied by the Automatic Dynamic Analysis of Mechanical System and Ansys Fluent Fluid Simulation software, respectively. The results show that the rotation rate was controlled at 41.8 mm/s, the various motion parameters are reasonable, and the operation process is relatively smooth, with high reliability. The speed and pressure value at the tip of the rotor are higher and the aerodynamic disturbance is obvious, which has a great influence on the aerodynamic performance. The speed and pressure distribution of the surrounding flow field is stable, the lift provided is 46 N, and the lift coefficient is 0.55, which can ensure the long-time suspension state of the missile. This paper puts forward a valuable design idea and has practical reference value for the research of the suspended missile.

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 Deformation Law and Control Measures of Gob-Side Entry Filled with Gangue in Deep Gobs: A Case Study

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xun Liu ◽  
Shihao Tu ◽  
Dingyi Hao ◽  
Yida Lu ◽  
Kaijun Miao ◽  
...  
Keyword(s):  
Coal Pillar ◽  
Stress Transfer ◽  
Control Measures ◽  
Theoretical Derivation ◽  
Simulation Research ◽  
Deformation Control ◽  
Deformation Problem ◽  
Working Face ◽  
Large Deformation Problem ◽  
Application Requirements

Aiming at the large deformation problem of gob-side entry in solid filling mining, the roof subsidence of gob-side entry retaining (GER) was studied under the influence of gangue filling, by taking a deep filling working face in Shandong Province as the engineering background and using theoretical derivation as well as FLAC3D numerical simulation. Research shows that the stiffness of the gangue filling body in the gob and the stiffness and width of the entry protection coal and rock mass (EPCARM) are positively correlated with the GER roof subsidence, which is much less affected by the EPCARM parameters than by the GER stiffness. The GER failure to meet the application requirements is mainly attributed to the insufficient stiffness of the gangue filling body and excessive advance subsidence, which inhibit the roof stress transfer. The GER replacement by the gob-side entry driving (GED) scheme, which implies replacing the entry protection gangue bag wall with the coal pillar with a width of 5 m, will reduce the roof subsidence to 0.114 m, according to the proposed equation. The results obtained are considered quite instrumental in deformation control of the gob-side entry filled with gangue, as well as substantiation of GED and GER applicability options.

Sign in / Sign up

Export Citation Format

Share Document