Comparative Analysis of Gas–Solid–Liquid Coupling Behavior in Front of the Working Face Before and After Water Injection During Coal Mining

2021 ◽  
Author(s):  
Yuexia Chen ◽  
Tingxiang Chu ◽  
Xuexi Chen ◽  
Peng Chen
Keyword(s):  
Comparative Analysis ◽  
Coal Mining ◽  
Water Injection ◽  
Working Face ◽  
Coupling Behavior ◽  
Before And After ◽  
Solid Liquid

scholarly journals Failure Depth of a Floor of a Fully Mechanized Working Face When Passing a Collapse Column

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Jinlong Cai ◽  
Min Tu ◽  
Wensong Xu
Keyword(s):  
Water Injection ◽  
Structural Defects ◽  
Concentration Coefficient ◽  
Working Face ◽  
Floor Failure ◽  
Before And After ◽  
Mining Face ◽  
Collapse Column ◽  
Failure Depth ◽  
Water Injection Test

The stress change law of a collapse column and the failure depth of a coal seam floor before and after mining when the fully mechanized coal mining face passes through the collapse column are investigated. Here, we present the constructed program in FISH language, render the damage variable in FLAC3D to establish the numerical model, and complete the numerical calculation. The 10–115 working faces that pass the collapse column at a coal mine in Tuanbai are identified as the research object. The floor failure is numerically simulated to assess the damage. The following results were obtained: the failure depth of the full floor is stabilized at 14.6 m; the maximum failure depth of the floor near the collapse column is 18.2 m; and the stress concentration coefficient is 1.27 times greater than that of normal mining. The calculated depth failure of the floor of the working face without structural defects is 14.6–14.7 m based on the Hoek–Brown criterion. With the collapse column, the failure depth of the floor is 16.8–17.8 m. According to the water injection test, the maximum failure depth of the floor is 18 m. The three derived values agree well with one another.

A Case Study on Development of Water-flow Fractured Zone During Close-Distance Repeated Coal Mining

2021 ◽  
Author(s):  
Yuanzhong Luan ◽  
Yaofan Shi ◽  
Shui Yu ◽  
Yue Dong ◽  
Yong Yan
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Water Flow ◽  
Water Injection ◽  
Scientific Basis ◽  
Hole Drilling ◽  
Fractured Zone ◽  
Working Face ◽  
Distance Working ◽  
Close Distance

Abstract The upper and lower seam of seam No.3 of some coal mines in Shandong Province are in close proximity which can be regards as close-distance coal seam mining.This paper takes the close-distance working face of Fucun coal mine as engineering background and mainly focuses on the investigation and research on inaccuracy of the forecasting and incompetence of the developing principles of water-flow fractured zone(WFFZ)during close-distance coal seam group mining.First,calculations on the height of WEEZ by adopting empirical formula.And FLAC3D software was established to calculate the height of the overburden WFFZ after repeated mining of the upper and lower seam of seam No.3.At the same time,using the double-ended water plugging observation technology of downhole drilling and upward hole drilling by analyzing the water injection loss ratio of the reference hole and the post-mining hole,the accurate numerical values of the WFFZ and the ratio of WFFZ height to mining height(W-M ratio)are obtained.The comparative analysis shows that the numerical simulation results are close to the measured ones,and the empirical formula is not applicable to the near-distance repeated mining.Finally,the prediction model is established based on the measured height of the WFFZ of multiple working faces,which provides a scientific basis for further exploring the development law of the overlying rock in underwater coal mining and ensuring the safe mining of coal seams at close distances.

scholarly journals Directional Hydraulic Fracturing (DHF) of the Roof, as an Element of Rock Burst Prevention in the Light of Underground Observations and Numerical Modelling

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 562
Author(s):  
Marek Jendryś ◽  
Andrzej Hadam ◽  
Mateusz Ćwiękała
Keyword(s):  
Rock Mass ◽  
Hydraulic Fracturing ◽  
Coal Mining ◽  
Rock Burst ◽  
Coal Mine ◽  
Seismic Activity ◽  
Black Coal ◽  
Directional Hydraulic Fracturing ◽  
Before And After ◽  
The Face

The following article analyzes the effectiveness of directional hydraulic fracturing (DHF) as a method of rock burst prevention, used in black coal mining with a longwall system. In order to define changes in seismic activity due to DHF at the “Rydułtowy” Black Coal Mine (Upper Silesia, Poland), observations were made regarding the seismic activity of the rock mass during coal mining with a longwall system using roof layers collapse. The seismic activity was recorded in the area of the longwall itself, where, on a part of the runway, the rock mass was expanded before the face of the wall by interrupting the continuity of the rock layers using DHF. The following article presents measurements in the form of the number and the shock energy in the area of the observed longwall, which took place before and after the use of DHF. The second part of the article unveils the results of numerical modeling using the discrete element method, allowing to track the formation of goafs for the variant that does not take DHF into consideration, as well as with modeled fractures tracing DHF carried out in accordance with the technology used at “Rydułtowy” coal mine.

scholarly journals Use of diesel and emulsified diesel in CI engine: A comparative analysis of engine characteristics

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110209
Author(s):  
Zain Ul Hassan ◽  
Muhammad Usman ◽  
Muhammad Asim ◽  
Ali Hussain Kazim ◽  
Muhammad Farooq ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Alternative Fuels ◽  
Fossil Fuels ◽  
Negative Impact ◽  
Water Injection ◽  
Load Range ◽  
Performance And Emission ◽  
Injection Methods ◽  
Ci Engine ◽  
Ci Engines

Despite a number of efforts to evaluate the utility of water-diesel emulsions (WED) in CI engine to improve its performance and reduce its emissions in search of alternative fuels to combat the higher prices and depleting resources of fossil fuels, no consistent results are available. Additionally, the noise emissions in the case of WED are not thoroughly discussed which motivated this research to analyze the performance and emission characteristics of WED. Brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) were calculated at 1600 rpm within 15%–75% of the load range. Similarly, the contents of NOx, CO, and HC, and level of noise and smoke were measured varying the percentage of water from 2% to 10% gradually for all values of loads. BTE in the case of water emulsified diesel was decreased gradually as the percentage of water increased accompanied by a gradual increase in BSFC. Thus, WED10 showed a maximum 13.08% lower value of BTE while BSFC was increased by 32.28%. However, NOx emissions (21.8%) and smoke (48%) were also reduced significantly in the case of WED10 along with an increase in the emissions of HC and CO and noise. The comparative analysis showed that the emulsified diesel can significantly reduce the emission of NOx and smoke, but it has a negative impact on the performance characteristics and HC, CO, and noise emissions which can be mitigated by trying more fuels variations such as biodiesel and using different water injection methods to decrease dependency on fossil fuels and improve the environmental impacts of CI engines.

scholarly journals Numerical Simulation and Engineering Application of Coalbed Water Injection

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Yijie Shi ◽  
Pengfei Wang ◽  
Ronghua Liu ◽  
Xuanhao Tan ◽  
Wen Zhang
Keyword(s):  
Numerical Simulation ◽  
Process Parameters ◽  
Water Injection ◽  
Engineering Application ◽  
Working Environment ◽  
Engineering Practice ◽  
Characteristic Parameters ◽  
Injection Process ◽  
Working Face ◽  
Dust Reduction

Coalbed water injection is the most basic and effective dust-proof technology in the coal mining face. To understand the influence of coalbed water injection process parameters and coalbed characteristic parameters on coal wetting radius, this paper uses Fluent computational fluid dynamics software to systematically study the seepage process of coalbed water injection under different process parameters and coalbed characteristic parameters, calculation results of which are applied to engineering practice. The results show that the numerical simulation can help to predict the wetness range of coalbed water injection, and the results can provide guidance for the onsite design of coalbed water injection process parameters. The effect of dust reduction applied to onsite coalbed water injection is significant, with the average dust reduction rates during coal cutting and support moving being 67.85% and 46.07%, respectively, which effectively reduces the dust concentration on the working face and improves the working environment.

scholarly journals Comparative Analysis Before and After Optimization of URL Detection Program

2019 ◽  
Vol 300 ◽  
pp. 042120
Author(s):  
Yi Yan ◽  
Lichao Zhan ◽  
Susheng Zhong ◽  
Xijun Lin ◽  
Xiaohui Mai ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Detection Program ◽  
Before And After

Comparative Analysis of Pesticide Residues in Agricultural Products in Circulation in Gyeonggi-do Before and After Positive List System Enforcement

2021 ◽  
Vol 36 (3) ◽  
pp. 239-247
Author(s):  
Seo-Hyeon Song ◽  
Ki-Yu Kim ◽  
Yun-Sung Kim ◽  
Kyong-Shin Ryu ◽  
Min-Seong Kang ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Pesticide Residues ◽  
Agricultural Products ◽  
Positive List ◽  
Before And After
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