scholarly journals Stability Control for the Rheological Roadway by a Novel High-Efficiency Jet Grouting Technique in Deep Underground Coal Mines

2019 ◽  
Vol 11 (22) ◽  
pp. 6494 ◽  
Author(s):  
Yuantian Sun ◽  
Guichen Li ◽  
Junfei Zhang ◽  
Deyu Qian
Keyword(s):  
Numerical Model ◽  
Coal Mining ◽  
High Efficiency ◽  
Coal Mines ◽  
Stability Control ◽  
Jet Grouting ◽  
Underground Coal Mines ◽  
Deep Underground ◽  
The Stability ◽  
Roadway Deformation

In maintaining the efficiency of coal mining, the stability of roadway plays a significant role, as it is closely related to the production of coal and the safety of personnel. In deep underground coal mines, the rheological deformation of roadway normally occurs, which affects its service life. To address this problem, in this paper, a novel high-efficiency Jet Grouting (JG) technique was presented, and its control effect on roadway stability was investigated. A creep test of a coal specimen in a laboratory scale was performed, and its creep behavior was revealed. The rheology of the coal mass surrounding the roadway was further analyzed according to the field-monitoring results of roadway deformation. A time-dependent numerical model with a Burger-creep visco-plastic model (CVISC) was established and validated by comparing the calculated displacement with in-situ measurement. The JG technique was tested in the field, and its applicability and practicability were confirmed. According to the validated model and field test results of JG, a numerical model with CVISC by JG support was established to analyze the effect of JG on the roadway. The results showed that the JG support can effectively reduce roadway deformation, optimize stress conditions, and reduce the extent of the plastic zone around the roadway. The rheological properties of the soft coal roadway were constrained and long-term stability was ensured. This pioneering work can guide the application of JG for the stability control of roadways and promote the sustainability of coal mining efficiently.

scholarly journals Long-term Analysis of the Effects of Production Management in Coal Mining in Poland

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3146 ◽  
Author(s):  
Izabela Jonek-Kowalska
Keyword(s):  
Coal Mining ◽  
Production Management ◽  
Coal Mines ◽  
Work Productivity ◽  
Policy Implications ◽  
Productivity Improvement ◽  
Mining Conditions ◽  
The Stability ◽  
Efficiency And Productivity

The primary aim of this article is to examine financial efficiency and work productivity, as well as their determinants, in selected Polish coal mines in 1998–2015. To achieve this goal, after introducing a justification for the choice of subject and the literature studies, the research methodology is presented, and research results are subsequently described and analyzed. Next, based on the main conclusions, model regularities and policy implications regarding efficiency and productivity improvement in Polish coal mining enterprises are established. The research for this study was conducted in five Polish coal mines, which were chosen on the basis of criteria aimed at ensuring the results’ comparability and the stability of organizational and mining conditions in the analyzed research period.

Virtual Analysis of the Mining Support under Loads of the Roof

2013 ◽  
Vol 837 ◽  
pp. 393-398 ◽  
Author(s):  
Aleksander Gwiazda
Keyword(s):  
Coal Mining ◽  
Coal Mines ◽  
Work Conditions ◽  
Coal Bed ◽  
Virtual Model ◽  
Virtual Analysis ◽  
The Stability ◽  
Roof Rocks ◽  
Investigation Process ◽  
Roof Support

The paper presents the results of virtual analysis of the stability of mining roof supports loaded by the roof rocks. The hydraulic roof support generally accounts for over 50% of the total value of a coal mining and excavating system. Many reports show that in some conditions roof supports behave differently than foreseen. To explain this phenomena the investigations basing on the virtual model were done [1,2]. This phenomena is very dangerous for miners because this behaviour of a mining roof support may cause dangerous accidents in coal mines. In the investigation process some questions have been asked. Firstly what type of a mining support is more liable to this behaviour. Secondly what work conditions are the most dangerous. To analyse this phenomena it was used models of two types of a mining support. One with two props and one with four ones. Results show that that the problem of plunged of roof parts of a support in the coal bed is consider with the construction of the support. The most dangerous is the roof support with two props. The consequences of this results are the recommendations to use rather supports with four props then two.

A Research on Stability Control for EMU Network Communication

2013 ◽  
Vol 846-847 ◽  
pp. 774-777
Author(s):  
Wei Zhang
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Data Communication ◽  
Doppler Frequency ◽  
Signal Propagation ◽  
Transmission Efficiency ◽  
Stability Control ◽  
Network Communication ◽  
The Stability ◽  
Communication Control

Conventional communication control methods cannot solve the Doppler frequency shift problem in high-speed moving network communication of EMU. The shift phenomenon in signal propagation, the high error rate and the low transmission efficiency make it's unable to ensure the stability of the high-speed communication network. Therefore, the paper designs the control model accordance with fuzzy estimation and data communication error correction for stability control of EMU network communications. Experimental results show that under the method delay and bandwidth changes of EMU communication is relatively stable, which means that the method can achieve high efficiency, high precision control for EMU network communication, and with a high application value.

scholarly journals Large-Deformation Failure Mechanism of Coal-Feeder Chamber and Construction of Wall-Mounted Coal Bunker in Underground Coal Mine with Soft, Swelling Floor Rocks

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Xingkai Wang ◽  
Wenbing Xie ◽  
Jianbiao Bai ◽  
Shengguo Jing ◽  
Zhili Su
Keyword(s):  
Coal Mines ◽  
Complex Problem ◽  
Tensile Failure ◽  
Steel Beams ◽  
Reinforcement Scheme ◽  
Floor Rock ◽  
Underground Coal Mine ◽  
Underground Coal Mines ◽  
Floor Heave ◽  
The Stability

In traditional vertical coal bunker systems, a coal-feeder chamber (CFC) must bear the whole weight of the bunker. However, maintenance of CFCs within soft, swelling floor rock is a challenge faced in underground coal mines. Floor-heave control is a complex problem and is still not well-solved. Moreover, there is no report on the construction of bunker without a CFC, especially under such weak floor-rock conditions. Based on the serious CFC collapse case at Xiashijie mine, China, this work analyzed the deformation characteristics, main influencing factors, and failure mechanisms of the CFC using a FLAC numerical model. The results indicate that the intrusion of water weakens the strength of the floor rock and causes significant expansive forces; thus, large deformations and tensile failure occur first in the floor, further causing shearing and tensile damage of the reinforced column and even overall instability of the CFC. Then, a new wall-mounted coal bunker (WMCB), without building the CFC, is proposed. The FLAC3D program was adopted to study the stability of the rocks surrounding the new bunker, and an optimized reinforcement scheme was determined. More importantly, a self-bearing system, which includes self-designed H-steel beams, H-steel brackets, and self-locking anchor cables, was proposed and constructed to bear the whole weight of the bunker. The stability of WMCB was verified by a theoretical safety assessment and field test. The invented WMCB could remain stable in spite of severe floor heave. This work can provide helpful references for the construction of vertical bunkers without CFCs in coal mines with soft, swelling floor rocks.

scholarly journals Stability Control of a Goaf-Side Roadway under the Mining Disturbance of an Adjacent Coal Working Face in an Underground Mine

2019 ◽  
Vol 11 (22) ◽  
pp. 6398
Author(s):  
Houqiang Yang ◽  
Changliang Han ◽  
Nong Zhang ◽  
Changlun Sun ◽  
Dongjiang Pan ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Stability Control ◽  
Surrounding Rock ◽  
Engineering Practice ◽  
Key Strata ◽  
Coal Recovery ◽  
Working Face ◽  
Underground Coal Mines ◽  
Mining Disturbance ◽  
The Stability

Goaf-side roadway driving could not only notably reduce the loss of coal resources and improve the coal recovery rates, but also greatly mitigate the imbalance between excavation speed and production needs, which are able to prolong the service life of the mine and are pivotal to sustainable and efficient development of underground coal mines. However, it is difficult to control the stability of the goaf-side roadway, especially under mining disturbance of another adjacent coal working face. In order to control the stability of the goaf-side roadway, Haulageway 1513 in the Xinyi Coal Mine of China, under mining disturbance, theoretical analysis, numerical simulation, and engineering practice were carried out to reveal the mechanism of overburden key strata fracture, stress distribution, and deformation characteristics of the surrounding rock of the goaf-side roadway due to mining disturbance. Results showed that some key strata above Goaf 1512 did not fracture due to the influence of the strata caving angles. However, these key strata would fracture and break into rock blocks when suffering from mining disturbance of the adjacent coal working face, which changed the stress distribution and increased the deformations of the surrounding rock of the goaf-side roadway. The combined techniques of pressure relief and bolt support were proposed and carried out to control the stability of the goaf-side roadway. Engineering practice indicated that the maximum deformations of the roof and sidewall-to-sidewall were 220 mm and 470 mm, respectively. The deformations of the goaf-side roadway under mining disturbance were efficiently controlled.

scholarly journals Stability Analysis of Roadway Groups under Multi-Mining Disturbances

2021 ◽  
Vol 11 (17) ◽  
pp. 7953
Author(s):  
Yuantian Sun ◽  
Ruiyang Bi ◽  
Qingliang Chang ◽  
Reza Taherdangkoo ◽  
Junfei Zhang ◽  
...  
Keyword(s):  
Coal Mining ◽  
Coal Pillar ◽  
Stability Control ◽  
Surrounding Rock ◽  
Key Strata ◽  
Working Face ◽  
Roadway Stability ◽  
Mining Disturbance ◽  
Mining Face ◽  
The Stability

The roadway stability has been regarded as the main challenging issue for safety and productivity of deep underground coal mines, particularly where roadways are affected by coal mining activities. This study investigates the −740 m main roadway in the Jining No. 2 Coal Mine to provide a theoretical basis for the stability control of the main deep roadway affected by disturbances of adjacent working activities. Field surveys, theoretical analyses, and numerical simulations are used to reveal mechanisms of the coal mining disturbance. The field survey shows that the deformation of roadway increases when the work face advances near the roadway group. Long working face mining causes the key strata to collapse based on the key strata theory and then disturbs the adjacent roadway group. When the working face is 100 m away from the stop-mining line, the roadway group is affected by the mining face, and the width roadway protection coal pillar is determined to be about 100 m. Flac3D simulations prove the accuracy of the theoretical result. Through reinforcement and support measures for the main roadway, the overall strength of the surrounding rock is enhanced, the stability of the surrounding rock of the roadway is guaranteed, and the safe production of the mine is maintained.

scholarly journals Improvement of production control of coal mining enterprises with underground mining method

2021 ◽  
Vol 303 ◽  
pp. 01017
Author(s):  
Tatyana Tyuleneva
Keyword(s):  
Coal Mining ◽  
Production Control ◽  
Underground Mining ◽  
Coal Mines ◽  
Underground Coal Mining ◽  
Safety Requirements ◽  
Production Control System ◽  
Production Safety ◽  
Foreign Countries ◽  
Underground Coal Mines

Production safety is one of the problems of competitiveness of underground mining enterprises, one manifestation of which is the reduction and minimization of the number of accidents and incidents of personal injury or even death. To solve this problem, it is necessary to improve the system of production control of coal mines in order to eliminate these factors. Relative indicators of accidents and injuries at underground coal mines of Russia in comparison with the average indicators are considered, and also importance of the human factor in the occurrence of dangerous production situations and the evaluation of their causes and effects are revealed. In addition, the article considers the most common violations of safety requirements for underground coal mining, analyzes the experience of foreign countries in improving the production control system, assesses the possibility of its application for improving production control at Russian coal mines, and determines main areas for implementing a risk-based approach at coal mining enterprises.

scholarly journals Methods of Stability Control of Perovskite Solar Cells for High Efficiency

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2918
Author(s):  
Abyl Muradov ◽  
Daria Frolushkina ◽  
Vadim Samusenkov ◽  
Gulsara Zhamanbayeva ◽  
Sebastian Kot
Keyword(s):  
Renewable Energy ◽  
High Efficiency ◽  
Perovskite Solar Cells ◽  
Stability Control ◽  
Metal Halide ◽  
High Power Conversion Efficiency ◽  
Energy Devices ◽  
Advantages And Disadvantages ◽  
Increasing Demand ◽  
The Stability

The increasing demand for renewable energy devices over the past decade has motivated researchers to develop new and improve the existing fabrication techniques. One of the promising candidates for renewable energy technology is metal halide perovskite, owning to its high power conversion efficiency and low processing cost. This work analyzes the relationship between the structure of metal halide perovskites and their properties along with the effect of alloying and other factors on device stability, as well as causes and mechanisms of material degradation. The present work discusses the existing approaches for enhancing the stability of PSC devices through modifying functional layers. The advantages and disadvantages of different methods in boosting device efficiency and reducing fabrication cost are highlighted. In addition, the paper presents recommendations for the enhancement of interfaces in PSC structures.

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