scholarly journals Research and Application of an Innovative 110 Mining Method in Gob-Side Half Coal Rock Entry Retaining

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Eryu Wang ◽  
Xiangdong Chen ◽  
Xiaojie Yang
Keyword(s):  
Recovery Rate ◽  
Mine Pressure ◽  
Mining Method ◽  
Time Consumption ◽  
Coal Recovery ◽  
Working Face ◽  
Constant Resistance ◽  
Movement Characteristic ◽  
Coal Rock ◽  
Maximum Subsidence

In order to solve the problems of the high cost and time consumption of half coal rock entry driving, low coal recovery rate, and stress concentration on filling support body of retained entry along gob, the innovative 110 mining method based on pressure relief by roof cutting was adopted in 6302 thin coal seam working face of Baoshan Coal Mine. First the technical principle and key technology of this mining method was presented. Then, through theoretical analysis and calculation, engineering experience, and field test, the key parameters such as the length of constant resistance anchor cable, the cutting angle and height of presplitting blasting, the charge structure, and the blocking-gangue support structure were determined and conducted in the retained entry. The broken expanded coefficient varying law of caved gangue with time and space was obtained, which revealed roof movement characteristic. The displacement monitoring curve of the roof and floor indicated that the maximum subsidence of the roof was about 150 mm and the maximum amount of floor heaving was 100 mm, which were quite small. The field monitoring data indicated that the entry retaining effect is good, which indicated that the innovative 110 mining method can be an effective way for reducing the high cost and time consumption of half coal rock entry driving, enhancing the coal recovery rate and preventing the dynamic mine pressure disasters.

Research on Mine Pressure Behave Law in Mining of Face under the Coal Pillar

2011 ◽  
Vol 217-218 ◽  
pp. 1721-1724
Author(s):  
Wei Shi ◽  
Hong Tao Liu ◽  
Cui Liang ◽  
Hou Sheng Jia
Keyword(s):  
Recovery Rate ◽  
Coal Pillar ◽  
Mine Pressure ◽  
Regular Pattern ◽  
Lower Face ◽  
Working Face ◽  
Correct Understanding ◽  
Close Distance ◽  
Protection Pillar

When mining close-distance seams with downlink mining, in order to benefit roof maintenance and management, the decoration of lower seam roadways should try to avoid the area affected by pillar concentrated stress , using inside cross decorationg; In order to improve the recovery rate of resources, the size of protection pillar can’t be too big, when mining under pillar of upper layer and mining in pillar of upper layer with crossing. The whole lower face or some phase located under the influence of upper coal concentration stress, give roadways and working face roof maintenance a lot of difficulties. Then it appeared the conflict between security and economy, to solve this problem, we must return to the correct understanding of mine pressure behave law. In the paper, through the investigation of the typical dozen example in mining of face the coal pillar in China, to get its regular pattern of mine pressure behave, in similar conditions mining, there will be important reference and guidance.

scholarly journals Comparative analysis of the mine pressure at non-pillar longwall mining by roof cutting and traditional longwall mining

2019 ◽  
Vol 16 (2) ◽  
pp. 423-438 ◽  
Author(s):  
Peng Zhou ◽  
Yajun Wang ◽  
Guolong Zhu ◽  
Yubing Gao
Keyword(s):  
Pressure Distribution ◽  
Coal Mining ◽  
Longwall Mining ◽  
Mining Industry ◽  
Mine Pressure ◽  
Mining Method ◽  
Working Face ◽  
Distribution Features ◽  
Mining Pressure ◽  
The Stability

Abstract Non-pillar coal mining has been developed and implemented in the recent decades in China's coal mining industry. The non-pillar longwall mining by roof cutting without pre-excavated entry (N00 mining method) is one of the latest non-pillar mining methods and this method has the advantages of reduced roadway drivage ratio and increased resource recovery ratio. Previous studies show that the mining pressure during the working face advancing is one of the main factors that affect the stability of underground structures and the safety production. However, there is no evaluation or analysis of the mining pressure at the mining face using entry retaining with roof pre-cutting and an absence of pre-excavated tail entry. In this paper, both field monitoring and numerical simulation approaches are employed in the analysis of the mining pressure distribution characteristics within a range of the whole working face during the face advancing. The results are compared with the field data and simulation results from the traditional mining method performed in the same coal mine. Results supported the idea that the N00 mining method can generate a low-stress area for the retained entry. The stability of the working face and retained entry can be well maintained due to the mine pressure optimization. This paper can aid in the understanding of structural mechanic modeling and mine pressure distribution features, structural mechanic analysis and mine pressure distribution features of the N00 mining method.

scholarly journals Study on the Characteristics of Top-Coal Caving and Optimization of Recovery Ratio in Steeply Inclined Residual High Sectional Coal Pillar

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Wenhua Yang ◽  
Xingping Lai ◽  
Pengfei Shan ◽  
Feng Cui ◽  
Yiran Yang
Keyword(s):  
Bulk Density ◽  
Coal Pillar ◽  
Engineering Practice ◽  
Recovery Ratio ◽  
Coal Seams ◽  
Balance System ◽  
Coal Recovery ◽  
Working Face ◽  
Coal Rock ◽  
Arch Structure

This paper is aimed at solving the technical problems such as low recovery ratio and frequent disasters in steeply inclined and extrathick coal seams at residual high sectional coal pillar. It takes the Wudong Coal Mine as an engineering background, a typical mine of steeply inclined and extrathick coal seams; the structural features of the top-coal caving at the steeply inclined residual high sectional coal pillar were analyzed using methods such as field monitoring and numerical simulation; a mechanical model of the top-coal arch structure was constructed, and the calculation method of top-coal caving height and related influencing factors was obtained. The results showed that the top-coal caving in the steeply inclined residual high sectional coal pillar was characterized as arch. Due to the existence of arch structure, the smooth caving of the top coal was hindered, resulting in a low top-coal recovery ratio, low support pressure at the working face, and differences detected by borehole television on the distribution of the top-coal cracks. With the advancement of the working face, the top-coal arch structure was in the process of dynamic evolution, as the old arch balance system was continuously replaced by the new arch balance system, and it continuously moved towards the upper top coal. The top-coal caving height was affected by factors such as length of the working face, bulk density of overlying coal rock, and cohesion of the top coal. The top-coal caving height increased with the length of the working face and the bulk density of the overlying coal rock mass but was inversely proportional to the cohesion of the top coal. Under the current mining conditions, the top-coal caving height was 39.8 m, which was much lower than the residual high sectional coal pillar height (71 m); the top coal cannot collapse completely. Based on the characteristics of the top-coal caving structure, the technology of sublevel advanced presplitting blasting was adopted to weaken the top coal in engineering practice, so that the top-coal caving structure moved up naturally. The daily coal production in the working face has increased by an average of 2419.6 tons, which has significantly improved the top-coal recovery ratio and production efficiency. The result provided a theoretical basis and application reference for similar residual high sectional coal pillar recovery.

scholarly journals Numerical Study of Reasonable Cycle Step Length for Longwall Top-coal Drawing in Extra-thick Coal Seams Based on the Particle-block Element Coupling Approach

2020 ◽  
Author(s):  
Yaochuang Wang ◽  
Dongyin Li ◽  
Shen Wang ◽  
Shiting Zhu ◽  
Zuguang Wang
Keyword(s):  
Recovery Rate ◽  
Step Length ◽  
Block Element ◽  
Coal Seams ◽  
Mixing Rate ◽  
Hydraulic Support ◽  
Coal Recovery ◽  
Coupling Approach ◽  
Rock Interface ◽  
Coal Rock

Abstract The cycle step length (CSL) is a significant parameter for longwall top-coal drawing technology that remarkably affects the top-coal recovery rate and the rock-mixing rate, especially for extra-thick coal seams. In this study, a particle-block element coupling approach is performed to investigate a reasonable CSL for extra-thick coal seams. By comparing this approach to the Bergmark-Roos analytical result, the proposed numerical model is verified, showing good performance in modeling top-coal caving. A 2-D numerical model of hydraulic support considering the mechanical behavior of the legs is established, which can be used for modeling the interaction between the hydraulic support and the top coals during the top-coal drawing process. The top-coal recovery rate, the top-coal drawing body shape, and the evolution characteristics of the coal-rock interface under different CSL conditions are compared. In addition, the mechanism of the lost top coal affected by the CSL is revealed. The results show that the CSL of top-coal drawing has a significant effect on the morphology of the coal-rock interface and the mutual invasion of coal and rock, which is the primary reason for coal loss and further affects the top-coal recovery rate and the rock-mixing rate. It is suggested that the CSL should be 0.8 m when the top-coal thickness is 12 m.

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 A numerical simulation of realistic top coal caving intervals under different top coal thicknesses in longwall top coal caving working face

2021 ◽  
Author(s):  
Chuang Liu ◽  
Huamin Li
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Distinct Element ◽  
Simulation Models ◽  
Simulation Software ◽  
Thick Coal Seam ◽  
Coal Recovery ◽  
Working Face ◽  
Longwall Top Coal Caving ◽  
Selection Of

Abstract In the process of longwall top coal caving, the selection of the top coal caving interval along the advancing direction of the working face has an important effect on the top coal recovery. To explore a realistic top coal caving interval of the longwall top coal caving working face, longwall top coal caving panel 8202 in the Tongxin Coal Mine is used as an example, and 30 numerical simulation models are established by using Continuum-based Distinct Element Method (CDEM) simulation software to study the top coal recovery with 4.0 m, 8.0 m, 12.0 m, 16.0 m, 20.0 m and 24.0 m top coal thicknesses and 0.8 m, 1.0 m, 1.2 m, 1.6 m and 2.4 m top coal caving intervals. The results show that with an increase in the top coal caving interval, the single top coal caving amount increases. The top coal recovery is the highest with a 0.8 m top coal caving interval when the thickness of the top coal is less than 4.0 m, and it is the highest with a 1.2 m top coal caving interval when the coal seam thickness is greater than 4.0 m. These results provide a reference for the selection of a realistic top coal caving interval in thick coal seam caving mining.

scholarly journals Mine Pressure Behavior Characteristics and Control Methods of a Reused Entry that Was Formed by Roof Cutting: A Case Study

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yajun Wang ◽  
Haosen Wang ◽  
Manchao He ◽  
Qi Wang ◽  
Yafei Qiao ◽  
...  
Keyword(s):  
Deformation Zone ◽  
Dynamic Pressure ◽  
Field Application ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Stress Increase ◽  
Severe Deformation ◽  
Working Face ◽  
Roof Deformation

Noncoal pillar mining with automatic formation of a roadway is a new coal mining method that is tailored to improve the coal resource recovery rate and reduce the investment in roadway tunneling. Using this proposed method, a reuse entry is formed by roof cutting instead of tunneling. In this paper, the S1201-II working face of the Ningtiaota Coal Mine was used as a case study. The stress distribution of surrounding rock and the roof deformation characteristics of the reused entry during the mining process of the second working face were studied through FLAC3D numerical simulations combined with field measurements. The results indicate that the zone close to the reused entry led to higher stress in advance. If this stress is superimposed with the lateral pressure of the adjacent mined working face, it will be more difficult to maintain the reused entry. In the engineering case study described here, the reused entry created a stress increase zone and a severe deformation zone in the range of 0–80 m in front of the working face, and its range was approximately 37.5% larger than an ordinary entry. The stress peak in the stress increase zone increased by approximately 34.7% over that of an ordinary entry. The maximum amount of deformation within the severe deformation zone increased by 94.4% over that of an ordinary entry. To properly control the surrounding rock stress and deformation of the reused entry, a dynamic pressure bearing support in front of the working face with adaptability to the large roof deformation and high support strength is proposed here. Field application results showed that the final roof deformation with the dynamic pressure bearing support can be satisfactorily controlled within 110∼130 mm. These findings can provide a reference for researchers and field engineering technicians when engaging in the support work of reused entry.

scholarly journals The Stability of Gob-Side Entry Retaining in a High-Gas-Risk Mine

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Junwen Zhang ◽  
Yulin Li
Keyword(s):  
Coal Mines ◽  
Surrounding Rock ◽  
Shanxi Province ◽  
Engineering Practice ◽  
Efficient Production ◽  
Coal Recovery ◽  
Working Face ◽  
Geological Conditions ◽  
The Stability ◽  
Strengthening Technique

There are series of problems faced by most of the coal mines in China, ranging from low-coal recovery rate and strained replacement of working faces to gas accumulation in the upper corner of coalfaces. Based on the gob-side entry retaining at the No. 18205 working face in a coal mine in Shanxi Province, theoretical analysis, numerical simulation, and engineering practice were comprehensively used to study the mechanical characteristics of the influence of the width of the filling body beside the roadway and the stability of surrounding rock in a high-gas-risk mine. The rational width of the filling body beside the roadway was determined, and a concrete roadway-side support with a headed reinforcement-integrated strengthening technique was proposed, which have been applied in engineering practice. The stability of the filling body beside the roadway is mainly influenced by the movement of the overlying rock strata, and the stability of the surrounding rock can be improved effectively by rationally determining the width of the filling body beside the roadway. When the width of the roadway-side filling body is 2.5 m, the surrounding rock convergence of the gob-side entry retaining is relatively small at only 5% of the convergence ratio. It has been shown that the figure for roof separation is relatively low, and strata behaviors are relatively alleviated and gas density do not exceed the limit, which are the best results of gob-side entry retaining. The results of this research can provide theoretical guidance for excavation of coal mines with similar geological conditions and have some referential significance to safety and efficient production in coal mines.

Cutting Roof Roadway Parameter Optimization Simulation Analysis

2015 ◽  
Vol 741 ◽  
pp. 179-182
Author(s):  
Yan Min Shu ◽  
Yong Li Liu
Keyword(s):  
Shear Stress ◽  
Stress State ◽  
Rock Strength ◽  
Simulation Analysis ◽  
Main Roof ◽  
High Impact ◽  
Mine Pressure ◽  
Working Face ◽  
Optimization Simulation ◽  
Concentration Degree

Contrast simulation analysis under different cutting distance between top lane, cut the top lane area stress state, according to different stress state analysis of the optimal cutting top lane spacing, so as to realize the optimization of cutting top lane setting parameters.Results show that due to the inhomogeneity of rock strength, the main roof breaking are mainly shear stress play a role, as a result, the vertical stress of roof fracture need conditions may be much smaller than mine pressure strength limit.Considering cutting top lane for the larger spacing, cutting the top coal lane area of stress concentration degree is higher, easy to cause impact danger, from this aspect to consider cutting the top lane spacing should be small as far as possible, but the spacing is too small and cut the top lane roadway of quantities will increase, at the same time has the potential to cut two top lane of the superposition of stress, high impact and increase the working face danger.

Study on the Structure Characteristics and Ground Pressure Behavior of Overlying Strata with Shallow Buried Coal Seam

2011 ◽  
Vol 255-260 ◽  
pp. 3780-3785 ◽  
Author(s):  
Lei Yu ◽  
Zhi Zhong Fan ◽  
Gang Xu
Keyword(s):  
Coal Seam ◽  
Ground Subsidence ◽  
Mine Pressure ◽  
Structure Characteristics ◽  
Pressure Behavior ◽  
Ground Pressure ◽  
Working Face ◽  
Periodic Pressure ◽  
Seam Mining ◽  
Overlying Strata

The mine pressure behavior characters of shallow buried coal seam differed from both shallow seam mining and general depth seam. Mine pressure observation and numerical analysis were applied to research mine pressure behavior laws in fully mechanized face of shallow buried coal seam with thick bedrock and thin alluvium. It showed that the ground subsidence level phenomenon did not appear obviously although with obvious dynamic loading of fully mechanized face during the pressure period. The appearance was due to non-synchronized fracture from two key layers in the overlying rock layers and their interaction, which leaded to roof breaking initially and caving rocks with the form of an arch. Due to the periodic breaking and caving characteristics appearing as fully cut-down and arch alternately, the periodic pressure of shallow buried coal seam face showed as different size. The conclusion could be a reference for similar working face control.

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