Optimization on Gateway Section of Soft Coal Seam and Hard Roof and Supporting Technology

2011 ◽  
Vol 90-93 ◽  
pp. 622-625
Author(s):  
Lu Chen ◽  
Chuan Wei Zang ◽  
Feng Hai Yu ◽  
Xiang Kun Yu
Keyword(s):  
Plastic Zone ◽  
Coal Seam ◽  
Field Application ◽  
Geological Condition ◽  
Hard Roof ◽  
Soft Coal ◽  
Production Safety ◽  
Geological Conditions ◽  
The Stability ◽  
Soft Coal Seam

Support invalidity of a roadway have a largely influence on production safety of coal mines, especially the soft coal roadway, which deforms heavily. To solve this problem, it began from the gateway section optimization, based on the actual geological condition of Chang-gouyu Mine. The computational model was established up to optimize tunnel shapes using FLAC3D. The scopes of plastic zone, stress field, displacement field were compared and analysed for different shapes of roadway. The irregular trapezoid section is adopted, then the bolt support parameters were designed and field application was done. By using the irregular trapezoid, the stress distribution around the roadway is improved and the deformation and plastic zone is decreased. Under the geological conditions of the soft coal seam and hard roof strata, the stability of roadway was effectively controlled by using optimized trapeziform cross-section and bolting support.

The Adaptation Analysis of the Fully Mechanized Coal Mining Face of Huopu Mine’s Third Soft Coal Seam

2014 ◽  
Vol 1049-1050 ◽  
pp. 335-338 ◽  
Author(s):  
Fa Quan Liu ◽  
Xue Wen Geng ◽  
Yong Che ◽  
Xiang Cui
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Geological Condition ◽  
Soft Coal ◽  
Working Face ◽  
Mining Face ◽  
Soft Coal Seam ◽  
Working Resistance

To get the maximum coal in front of the working face of the 17# coal seam, we installed a longer beam which is 1.2m in length in the leading end of the original working face supports ZF3000/17/28, and know that working face supports’ setting load and working resistance are lower .We changed the original supports with shield supports ZY3800/15/33 that are adaptable in the geological condition and got the favorable affection.

scholarly journals Stability Assessment of Deep Three-Soft Outburst Coal Seam Roof Based on Fuzzy Analytic Hierarchy Process

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Qingling Meng ◽  
Yanling Wu ◽  
Minbo Zhang ◽  
Zichao Wang ◽  
Kejiang Lei
Keyword(s):  
Coal Seam ◽  
Analytic Hierarchy Process ◽  
Evaluation Method ◽  
Stability Assessment ◽  
Analytic Hierarchy ◽  
Soft Coal ◽  
Outburst Coal Seam ◽  
The Stability ◽  
Soft Coal Seam ◽  
Hierarchy Process

The stability of deep “three-soft” coal seam roof has always been a key issue in coal mining. There are a lot of factors affecting the stability of deep three-soft coal seam outburst roof. However, there is currently no definite method able to draw an accurate assessment conclusion on roof stability. In order to accurately determine the main influencing factors of the stability of deep three-soft coal seam outburst roof and reduce the loss of coal production, this paper performed three-soft coal seam risk identification on Lugou Mine based on the introduction of the fuzzy analytic hierarchy process theory. 23 main risk factors were identified. Then, it established a hierarchical structure model of coal seam roof stability in accordance with experts’ opinions. The analytic hierarchy process was used to calculate the weights of indicators at all levels. Next, the paper used the fuzzy comprehensive evaluation method and expert scoring to evaluate various risk factors in the indicator system, as well as the overall safety level. The results showed that the deep three-soft coal seam stability of Lugou Mine ranks the third hazard level. The main risk and harmful factors include safety awareness, safety monitoring system, roof weakness, ventilation system, fire-fighting system, and rock bolt quality. In response to the evaluation results, this paper formulated corresponding control measure in terms of ventilation risk, safety monitoring risks, construction personnel risks, and fire protection risk to reduce losses in the mining process, providing a new evaluation method for the stability assessment of deep outburst coal seam roof.

scholarly journals Theory and Application of Gob-Side Entry Retaining in Thick Three-Soft Coal Seam

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Junchao Shen ◽  
Ying Zhang
Keyword(s):  
Coal Seam ◽  
Engineering Practice ◽  
Coal Seams ◽  
High Resource ◽  
Soft Coal ◽  
Geological Conditions ◽  
Body Construction ◽  
Roadway Support ◽  
Soft Coal Seam ◽  
Engineering Scheme

With the characteristic of less roadway excavation and high resource recovery, gob-side entry retaining (GER) technology is a safe and efficient green mining technology. Many experts and scholars have done extensive research on its principle and application. However, GERs are rarely used in thick soft coal seams. In this paper, based on the geological conditions of a coal mine in China, we propose a novelty approach of GER in thick three-soft coal seam (it means a single seam with a soft roof and a soft floor). The engineering scheme includes roadway expansion, large section roadway support, cutting roof to relieve pressure, and road-inside backfill body construction. The established mechanical and numerical calculation models effectively guide the engineering practice. Field observations showed that all the processes met the requirements of field production. The research results could provide theoretical guidance for the application of GER under similar geological conditions.

The New Technology of Hydraulic Fracturing Soft Coal Rock Permeability Improvement

2014 ◽  
Vol 1030-1032 ◽  
pp. 1255-1259 ◽  
Author(s):  
Xue Xi Chen ◽  
Yan Ke Zhang ◽  
Yong Xu ◽  
Rui Qing Bi
Keyword(s):  
Coal Seam ◽  
New Technology ◽  
Water Injection ◽  
Injection Pressure ◽  
Field Application ◽  
Good Effect ◽  
Gas Extraction ◽  
Soft Coal ◽  
Coal Rock ◽  
Soft Coal Seam

According to the low intensity, good plasticity in soft coal seam, the effect of direct fracturing to increase permeability was not ideal, the new technology of hydraulic fracture soft coal rock was proposed, which increased coal seam permeability. Its technical principles and characteristics were researched. Water injection pressure was analyzed, including injection time, parameters of the technology and so on. Field application experiment and effect of inspection were conducted. The results showed that the concentration of gas extraction increased 4.3 times, and the gas extraction flow increased 6.2times. The technology has a good effect of fracturing and advantages in enlarging the released area and decreasing diffusion seepage resistance of coal seam. Most important, the technology has broad application prospects in soft coal seam.

Numerical Analysis on Top Coal Caving of 2# Coal Seam in First Mine of Chagannaoer

2012 ◽  
Vol 594-597 ◽  
pp. 1338-1342
Author(s):  
Qing Hai Li ◽  
Ren Shu Yang ◽  
Wei Ping Shi
Keyword(s):  
Numerical Analysis ◽  
Plastic Zone ◽  
Coal Seam ◽  
Comprehensive Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Mining Technology ◽  
Geological Conditions ◽  
Numerical Software ◽  
Evolution Laws ◽  
Overlying Strata

In first mine of Chagannaoer, 2# coal seam, the mainly mined out layer, was 22.00m thickness in average. In order to meet the requirements of production ability, the mine was planned to apply mining technology of fully mechanized caving. Good or bad of top coal’s caving was an important prerequisite which decided the mining technology of top coal caving could be chosen or not. Due to lack of producing mines in this region and no experience to refer, we simulated the mining process of 2# coal seam using numerical software of FLAC3D, and gained evolution laws of stress and displacement of top coal and overlying strata and expansion laws of plastic zone. Through analysis, we got that the top coal damaged seriously and the top coal could be caved smoothly. Relying on the geological conditions of site, we verified the simulated results with method of fuzzy comprehensive evaluation. Combined with the research results, we decided that 2# coal seam’s caving was better and was convenient for top coal caving, so it was suitable for caving mining in 2# coal seam in first mine of Chagannaoer.

scholarly journals Permeability Enhancement Properties of High-Pressure Abrasive Water Jet Flushing and Its Application in a Soft Coal Seam

2021 ◽  
Vol 9 ◽  
Author(s):  
Xinzhe Zhang ◽  
Piotr Wiśniewski ◽  
Sławomir Dykas ◽  
Guojie Zhang
Keyword(s):  
High Pressure ◽  
Coal Seam ◽  
Water Jet ◽  
Gas Pressure ◽  
Theory And Practice ◽  
Abrasive Water Jet ◽  
Gas Drainage ◽  
Permeability Enhancement ◽  
Soft Coal ◽  
Soft Coal Seam

High-pressure abrasive water jet flushing (HPAWJF) is an effective method used to improve coal seam permeability. In this study, based on the theories of gas flow and coal deformation, a coupled gas-rock model is established to investigate realistic failure processes by introducing equations for the evolution of mesoscopic element damage along with coal mass deformation. Numerical simulation of the failure and pressure relief processes is carried out under different coal seam permeability and flushing length conditions. Distributions of the seepage and gas pressure fields of the realistic failure process are analyzed. The effects of flushing permeability enhancement in a soft coal seam on the gas drainage from boreholes are revealed by conducting a field experiment. Conclusions can be extracted that the gas pressure of the slotted soft coal seam is reduced and that the gas drainage volume is three times higher than that of a conventional borehole. Field tests demonstrate that the gas drainage effect of the soft coal seam is significantly improved and that tunneling speed is nearly doubled. The results obtained from this study can provide guidance to gas drainage in soft coal seams regarding the theory and practice application of the HPAWJF method.

scholarly journals Research on Control of Rib Spalling Disaster in the Three-Soft Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Feng Cui ◽  
Tinghui Zhang ◽  
Xiaoqiang Cheng
Keyword(s):  
Coal Seam ◽  
Field Experiments ◽  
Simulation Experiment ◽  
Current Status ◽  
Soft Coal ◽  
Grouting Pressure ◽  
Working Face ◽  
Coal Wall ◽  
Soft Coal Seam ◽  
Seam Mining

Rib spalling disaster at the coal mining faces severely restricted the safe and efficient output of coal resources. In order to solve this problem, based on the analysis of the current status of rib spalling in the three-soft coal seam 1508 Working Face of Heyang Coal Mine, a mechanical model of sliding-type rib spalling was established and the main influencing factors that affect rib spalling are given. The mechanism of grouting technology to prevent and control rib spalling has been theoretically analyzed. A similarity simulation experiment is used to analyze the change law of roof stress under the condition of three-soft coal seam mining. The optimal grouting pressure is determined by a numerical simulation experiment. And, silicate-modified polymer grouting reinforcement materials (SMPGMs) are used in field experiments. After twice grouting operations in the 1508 Working Face, the coal wall was changed from the original soft and extremely easy rib spalling to a straight coal wall and the amount of rib spalling has been reduced by 57.45% and 48.43, respectively. And, the mining height has increased by 0.16 m and 0.23 m, respectively. The experimental results show that the rib spalling disaster of the three-soft coal seam has been effectively controlled.

scholarly journals Application of Sampling Method Based on Negative Pressure Pneumatic Conveying in Soft Coal Seam

2016 ◽  
Vol 34 (3) ◽  
pp. 473-478
Author(s):  
Hongtu Zhang ◽  
Jianping Wei ◽  
Yungang Wang ◽  
Zhihui Wen ◽  
Banghua Yao
Keyword(s):  
Coal Seam ◽  
Negative Pressure ◽  
Sampling Method ◽  
Pneumatic Conveying ◽  
Soft Coal ◽  
Soft Coal Seam

Coal and gas outburst mechanism of the “Three Soft” coal seam in western Henan

2010 ◽  
Vol 20 (5) ◽  
pp. 712-717 ◽  
Author(s):  
Dongji LEI ◽  
Chengwu LI ◽  
Zimin ZHANG ◽  
Yugui ZHANG
Keyword(s):  
Coal Seam ◽  
Coal And Gas Outburst ◽  
Gas Outburst ◽  
Soft Coal ◽  
Soft Coal Seam

scholarly journals Research and Application of Hydraulic Punching Pressure Relief Antireflection Mechanism in Deep “Three-Soft” Outburst Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Beifang Gu ◽  
Yanling Wu
Keyword(s):  
Coal Seam ◽  
Large Scale ◽  
Water Pressure ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Technical Problems ◽  
Soft Coal ◽  
Coal Rock ◽  
Outburst Coal Seam ◽  
Soft Coal Seam

To solve the problems of gas predrainage in deep seams with “three softs” and low-air permeability, hydraulic punching pressure relief antireflection technology is proposed on the basis of the research background of gas predrainage technology in Lugou Mine to alleviate technical problems, such as low gas drainage efficiency, in this mine. Through the analysis of the mechanism of hydraulic punching and coal breaking, combined with FLAC3D software, a hydraulic punching pressure relief antireflection model is established. Then, the fracture radii of coal rock are simulated and calculated. The results show that, under hydraulic punching with a water pressure of 10 MPa and coal outputs of 3 m3, 6 m3, 9 m3, and 12 m3, the fracture radii of coal and rock are 3.4 m, 4.8 m, 5.5 m, and 5.9 m, respectively. Using the software to fit the relationship between coal output V and hydraulic punching fracture radius R under the same water pressure, R = 2.32479 V0.3839 is obtained. The field test is carried out in the bottom drainage roadway of 32141 in Lugou Mine. The application effect is as follows: the gas concentration of hydraulic punching with a coal output of 3 m3 is twice that of ordinary drilling, and the coal output of hydraulic punching with a coal output of 6 m3 is four times that of ordinary drilling. The extraction concentration is four times that of ordinary drilling, and the extraction concentration of hydraulic punching with a coal output of 9 m3 is 6.4 times that of ordinary drilling. Combining the results of the numerical simulation and taking into account the actual construction situation on site, the coal output of water jetting from the borehole is 9 m3, and the fracture radius is 5.5 m. This outcome means that the effective half radius is 5.5 m, and the borehole spacing is 7.7 m. These values are the construction parameters for large-scale applications. This proposal provides effective technology and equipment for gas drainage in the deep three-soft coal seam. Consequently, it has promotion and reference significance for gas drainage in coal seam of the same geological type.

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