Analysis of Weighting over Great Extent upon Fully Mechanized Coal Face with Non-Hard Roof Based on Measured Data

2014 ◽  
Vol 962-965 ◽  
pp. 992-997
Author(s):  
Tao Zhu
Keyword(s):  
Experimental Analysis ◽  
Safety Valve ◽  
Measured Data ◽  
Large Area ◽  
Coal Face ◽  
Hydraulic Support ◽  
Mining Technology ◽  
Hard Roof ◽  
Drawing Speed ◽  
Working Face

Due to the influence of geology, mining technology, supporting strength, fully mechanized coal face sometimes would happen large area caving and weighting over great extent, causing casualties. Theoretical and experimental analysis shows, not only hard roof could happen weighting over great extent, but softer roof upon long wall face could happen, the only difference was the location of disaster and the failure forms. The paper analyzed weighting over great extent upon fully mechanized coal face with non-hard roof based on measured data. The results show that, the important factors of support break-off were the setting load of hydraulic support, drawing speed of working face and support efficiency, and it would achieve support break-off warning help to analyze the open rates of safety valve.

Gas Control Technology for Fully Mechanized Face of Outburst Coal Seam with Hard Roof during Initial Caving

2011 ◽  
Vol 347-353 ◽  
pp. 974-978
Author(s):  
Ju Gen Fu ◽  
Wei Wu ◽  
Gen Yong Hua
Keyword(s):  
Coal Seam ◽  
Shock Pressure ◽  
Control Technology ◽  
Large Area ◽  
Hard Roof ◽  
Working Face ◽  
Initial Release ◽  
Gob Area ◽  
Outburst Coal Seam ◽  
Presplit Blasting

In the fully mechanized working face, with working face forward, gob area become bigger and bigger, when the top area reach a certain span ,roof in gob suddenly cave, outspreading a large quantity of mine gas, easy to cause the gas overrun and gas accidents. In addition, shock pressure which is caused when large area roof cave, easily causing casualties and damage of equipment. This paper introduces Pan three Coal mine 17171(1) ore advance of fully mechanized working face presplit blasting, rotating stoping and comprehensive extraction technologies, which successfully solve the roof management and the gas problems during initial release, achieving good security benefits.

scholarly journals Prevention Technology for Strong Mine Pressure Disaster in the Hard-Roof Large-Mining-Height Working Face

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Hongfei Duan ◽  
Lijuan Zhao
Keyword(s):  
Hydraulic Fracturing ◽  
Hard Rock ◽  
Mine Pressure ◽  
Overburden Rock ◽  
Large Area ◽  
Rock Stratum ◽  
Hard Roof ◽  
Working Face ◽  
Large Mining Height ◽  
Mining Height

The movement and destruction of the hard roof in a stope is an important reason for the occurrence of strong ground pressure disasters at the working face. Considering Tongxin Coal Mine as the engineering background, the stress distribution law of the surrounding rock and the overburden rock damage characteristics of a large-mining-height working face under the hard roof were investigated. To solve the problem whereby the stope’s hard roof is difficult to collapse, the hard rock key stratum of the roof was hydraulically fractured to weaken the mechanical properties of the roof rock stratum. Additionally, microseismic monitoring technology was used to monitor the cracking effect of the rock stratum. The theoretical calculation and numerical simulation results reveal that, after hydraulic fracturing, a crack with a more consistent trend formed inside the hard rock stratum and a large area of the rock stratum was damaged. According to the monitoring results of the stope stress after hydraulic fracturing, the law governing the occurrence of the leading bearing pressure was in effect. In contrast, the influence range and peak strength of the leading bearing pressure were considerably reduced at the working face after hydraulic fracturing. After performing hydraulic fracturing on the roof of the working face, the bearing pressure of the working face can satisfy the production requirements better. Finally, the results obtained through this study can be used as a reference for determining the width of coal pillars under similar mining conditions.

Research on Mining Engineering with Dual Gradient High Inclination-Angle Fully Mechanized Mining Technology

2014 ◽  
Vol 977 ◽  
pp. 231-234 ◽  
Author(s):  
Xin Song ◽  
Li Min Wang
Keyword(s):  
Coal Seam ◽  
Inclination Angle ◽  
Coal Mine ◽  
Mining Engineering ◽  
Hydraulic Support ◽  
Mining Technology ◽  
Research Site ◽  
Working Face ◽  
Dual Gradient

In this paper, it will take in-depth research, site practical methods, and provide reasonable solutions to several key problems, such as conveyor and hydraulic support sliding；shearers badly sloped；the roof management of return airway when the working face lengthened；dealing with the upper corner gas；gangue fleeing；turn mining，which seriously affect production during high inclination-angle fully mechanized mining at 3# coal seam of the second mining section of ChengShan coal mine.

scholarly journals A Method Based on Elastic Mechanics for Judging Compound Hard Roof and Its Application

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Haiyang Wang ◽  
Xiang Chen ◽  
Yanmin Zhou ◽  
Binwei Xia ◽  
Jie Wang ◽  
...  
Keyword(s):  
Stress Field ◽  
Mechanical Model ◽  
Large Deviation ◽  
Similar Model ◽  
Coal Face ◽  
Hard Roof ◽  
Working Face ◽  
The Common ◽  
Set Up ◽  
Elastic Mechanics

Compound hard roof overlying coal face is the common disaster factor leading to strong strata behaviors. To solve the long-standing problems of only considering partial factors and large deviation from the actuality when identifying compound hard roof, a mechanical model of compound hard roof based on elastic mechanics is built, from which the stress field distribution equations of compound hard roof are formed and the judging criteria of compound hard roof have been set up. In this essay, 8101 Working Face of Tashan Coal Mine in China is the research object for criteria and analysis of compound hard roof, and the result is testified by similar model tests. The research results have provided a basis for judging and dealing with compound hard roof.

scholarly journals Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

scholarly journals Safety Warning Model of Coal Face Based on FCM Fuzzy Clustering and GA-BP Neural Network

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1082
Author(s):  
Fanqiang Meng
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Early Warning ◽  
Back Propagation ◽  
Back Propagation Neural Network ◽  
Coal Face ◽  
Early Warning Model ◽  
Working Face ◽  
The Neural Network ◽  
Warning Model

Risk and security are two symmetric descriptions of the uncertainty of the same system. If the risk early warning is carried out in time, the security capability of the system can be improved. A safety early warning model based on fuzzy c-means clustering (FCM) and back-propagation neural network was established, and a genetic algorithm was introduced to optimize the connection weight and other properties of the neural network, so as to construct the safety early warning system of coal mining face. The system was applied in a coal face in Shandong, China, with 46 groups of data as samples. Firstly, the original data were clustered by FCM, the input space was fuzzy divided, and the samples were clustered into three categories. Then, the clustered data was used as the input of the neural network for training and prediction. The back-propagation neural network and genetic algorithm optimization neural network were trained and verified many times. The results show that the early warning model can realize the prediction and early warning of the safety condition of the working face, and the performance of the neural network model optimized by genetic algorithm is better than the traditional back-propagation artificial neural network model, with higher prediction accuracy and convergence speed. The established early warning model and method can provide reference and basis for the prediction, early warning and risk management of coal mine production safety, so as to discover the hidden danger of working face accident as soon as possible, eliminate the hidden danger in time and reduce the accident probability to the maximum extent.

scholarly journals Study and Application of Roof Cutting Pressure Releasing Technology in Retracement Channel Roof of Halagou 12201 Working Face

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Ma Xingen ◽  
He Manchao ◽  
Wang Yajun ◽  
Zhang Yong ◽  
Zhang Jiabin ◽  
...  
Keyword(s):  
High Stress ◽  
Hydraulic Support ◽  
Working Face ◽  
Geological Conditions ◽  
Support Resistance ◽  
Cutting Effect ◽  
Mining Pressure ◽  
Cutting Height ◽  
First Time ◽  
Roof Deformation

The retracement channel roof cutting (RCRC) technology can change the overburden structure actively by cutting off the roof of channel along the direction of working face tendency and make use of the gangue collapsing from roof cutting range to fill the goaf and weaken the mining pressure during the retracement process of working face. In order to solve the problems of high stress in surrounding rock and serious deformation of retracement channel in Halagou coal mine, it is the first time that the pressure releasing test is carried out on the 12201 working face by the method of the directional presplitting roof cutting in retracement channel. First, according to statics theory and energy theory, the stress state of hydraulic support and roof deformation mechanism of retracement channel are analyzed. Then the roof cutting design of retracement channel is determined according to the geological conditions of 12201 working face, and the cutting effect is analyzed by numerical simulation. Finally, the field test is carried out on the 12201 working face to verify the effect of pressure releasing by roof cutting. The result shows that, with the roof cutting design including the roof cutting height being 8m and roof cutting angle being 45°, the roof subsidence of the 12201 working face retracement channel in Halagou mine is reduced to 132.5mm, and the hydraulic support resistance is maintained at 1361KN. And there is no hydraulic support crushed; the deformation of the retracement channel is also small; namely, the effect of roof cutting for pressure releasing is obvious.

scholarly journals Energy and thermal modeling of building façade integrated photovoltaics

2018 ◽  
Vol 22 (Suppl. 3) ◽  
pp. 921-932 ◽  
Author(s):  
Konstantinos Ordoumpozanis ◽  
Theodoros Theodosiou ◽  
Dimitrios Bouris ◽  
Katerina Tsikaloudaki
Keyword(s):  
Electricity Generation ◽  
Measured Data ◽  
Building Envelope ◽  
Zero Energy ◽  
Large Area ◽  
Finite Volume Model ◽  
Volume Model ◽  
Urban Buildings ◽  
Zero Energy Building ◽  
Integrated Performance

Electricity generation on site is a design challenge aiming at supporting the concept of energy-autonomous building. Many projects worldwide have promoted the installation of photovoltaic panels on urban buildings, aiming at utilizing a large area to produce electricity. In most cases, photovoltaics are considered strictly as electricity generators, neglecting their effect to the efficiency and to the thermal behaviour of the building envelope. The integrated performance of photovoltaic ventilated fa?ades, where the photovoltaics are regarded as part of a complicated envelope system, provides design challenges and problems that cannot be overlooked within the framework of the Nearly Zero Energy Building concept. In this study, a finite volume model for photovoltaic ventilated fa?ades is developed, experimentally validated and found to have a significant convergence to measured data.

scholarly journals Study on the Fracture Law of Inclined Hard Roof and Surrounding Rock Control of Mining Roadway in Longwall Mining Face

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5344
Author(s):  
Feng Cui ◽  
Shuai Dong ◽  
Xingping Lai ◽  
Jianqiang Chen ◽  
Chong Jia ◽  
...  
Keyword(s):  
Energy Release ◽  
Longwall Mining ◽  
Coal Pillar ◽  
High Energy ◽  
Mechanical Analysis ◽  
Engineering Practice ◽  
Analysis Model ◽  
Hard Roof ◽  
Working Face ◽  
The Stability

In the inclination direction, the fracture law of a longwall face roof is very important for roadway control. Based on the W1123 working face mining of Kuangou coal mine, the roof structure, stress and energy characteristics of W1123 were studied by using mechanical analysis, model testing and engineering practice. The results show that when the width of W1123 is less than 162 m, the roof forms a rock beam structure in the inclined direction, the floor pressure is lower, the energy and frequency of microseismic (MS) events are at a low level, and the stability of the section coal pillar is better. When the width of W1123 increases to 172 m, the roof breaks along the inclined direction, forming a double-hinged structure, the floor pressure is increased, and the frequency and energy of MS events also increases. The roof gathers elastic energy release, and combined with the MS energy release speed it can be considered that the stability of the section coal pillar is better. As the width of W1123 increases to 184 m, the roof in the inclined direction breaks again, forming a multi-hinged stress arch structure, and the floor pressure increases again. MS high-energy events occur frequently, and are not conducive to the stability of the section coal pillar. Finally, through engineering practice we verified the stability of the section coal pillar when the width of W1123 was 172 m, which provides a basis for determining the width of the working face and section coal pillar under similar conditions.

Sign in / Sign up

Export Citation Format

Share Document