scholarly journals Theoretical and Experimental Study on the Mechanism of Instability and Firing Gas in Hard Quartz Sandstone

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Jianqiang Liu ◽  
Guangpeng Qin ◽  
Jing Cao ◽  
Minghua Zhai ◽  
Yunxin Pei
Keyword(s):  
Friction Velocity ◽  
Efficient Production ◽  
Gas Explosion ◽  
Gas Concentration ◽  
Friction Effect ◽  
Working Face ◽  
Geological Conditions ◽  
And Control ◽  
Roof Strata ◽  
Relative Friction

The upper part of high gas coal seam often has a hard and thick sandstone roof, which provides the condition for the occurrence of gas accident in goaf caused by the friction effect for the sliding and instability of hard quartz sandstone. Based on the engineering background of the 1007 working face of Xiakuotan Coal Mine, the conditions of sliding instability of hard quartz sandstone and the possibility of the friction effect are discussed by combining theoretical analysis with the laboratory test. When the ratio of span to thickness is less than 2∼2.56, the hard-thick sandstone strata may slip and lose stability. The influence of friction velocity and gas concentration on the induced gas of quartz sandstone is analyzed and compared. The results show that the point spark, the spark beam, and the gas explosion time are inversely proportional to the relative friction velocity, and the intensity of the gas explosion is directly proportional to the gas concentration and the relative friction velocity. This paper provides the basis for the prevention and control of gas disasters in goaf and the control of hard and thick sandstone roof strata under similar engineering geological conditions. It is of great significance to promote the safe and efficient production of coal mines and to ensure the safety of personal and property.

scholarly journals Study on the Mechanism of Gas Ignition by Friction Effect of Hard Quartz Sandstone Instability

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Li Fuqiang ◽  
Qin Guangpeng ◽  
Liu Yonggang ◽  
Wang Qichen ◽  
Wang Ying ◽  
...  
Keyword(s):  
Coal Seam ◽  
Hard Rock ◽  
Gas Explosion ◽  
Friction Process ◽  
Friction Effect ◽  
Working Face ◽  
Geological Conditions ◽  
Gas Ignition ◽  
Overlying Strata ◽  
Sliding Instability

When the upper part of a high gas coal seam has hard and thick sandstone roof, the gas explosion accident in goaf is even caused by roof collapse. Taking the mining of 1007 working face of 10 coal seam under Xia KuoTan Coal Mine as the engineering background, using the method of indoor experiment and theoretical analysis, the possibility of rock friction effect igniting gas is studied. Under the engineering geological conditions, the results show that the heat produced by the friction process of hard sandstone can ignite gas. According to the 3DEC numerical simulation, the instability characteristics of the overburden hard rock are studied. The results show that the size of the slab instability area is not changed when the length of the working face increases. When the thickness of the roof is increased, the area of sliding instability is increased and the degree of sliding instability is more intense. At the boundary of the tunnel, the overlying strata are subjected to the largest shear stress, and it tends to form a friction surface with greater slip instability.

scholarly journals Research on the Source Mechanism and Source Prevention and Control System of Deep Rock Burst

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Shuai Di
Keyword(s):  
Control System ◽  
Rock Mass ◽  
Rock Burst ◽  
Prevention And Control ◽  
Economic Benefits ◽  
Efficient Production ◽  
Targeted Prevention ◽  
Working Face ◽  
Deep Rock ◽  
And Control

Deep rock burst accidents occur frequently and become increasingly serious. Further improving the effectiveness and accuracy of the prevention and control of rock burst, ensuring the safe and efficient production of mines, clarifying the basic causes of disasters, and refining the type of deep rock burst are the most important key links. Aiming at the problems such as unclear incentives and types and the lack of effective and targeted prevention measures of deep rock burst, taking Xin’an Mine as the research background, based on the energy theory, the coal and rock mass multisource energy unified equation was established to analyze coal and rock mass instability mechanism. According to the different degrees of participation of various factors, the types of deep rock burst are determined as three categories and four types, and the corresponding judgment criteria are proposed. The precise prevention and control system for the source of rock burst with Xin’an characteristics is proposed, successfully applied to the 8101 working face, which not only guarantees the safe production of the working face, but also achieves good economic benefits. The research results lay the foundation for improving the accuracy and precision of the prevention and control of deep rock burst and provide theoretical guidance for the safe and efficient mining of the mine.

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.

scholarly journals Gas Distribution Mechanism in Goaf during Combined Drainage of Upper Corner Buried Pipeline and Intubation for Thick Coal Seams

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Zhe Li ◽  
Fangtian Wang ◽  
Shuai Ren ◽  
Guannan Liu
Keyword(s):  
Buried Pipeline ◽  
Coal Seams ◽  
Gas Drainage ◽  
Gas Concentration ◽  
Geological Conditions ◽  
Key Issues ◽  
Fluent Software ◽  
Gas Control ◽  
Drainage Effect ◽  
And Control

Abstract The prevention of gas overrun in the panel is one of the key issues on green mining. In this paper, a physical goaf model was established based on the geological production conditions of a coal seam in a coal mine in Henan Province, and the combined drainage technology by burying and spilling pipeline in the upper corner was proposed. The Fluent software was used to simulate the changes of gas mass fraction and flow field distribution when the gas is extracted from the goaf without the gas pipeline, with a single buried pipeline, and with the combination of buried and spilled pipelines. Analysis and simulation showed that in the absence of drainage pipelines, the gas concentrations in both the return airway and the upper corner are up to 1.2%, which failed to meet the gas prevention and control standard on the mine. In the case of gas drainage with a single buried pipeline, the average gas concentration in the return airway was 0.7%, and only the gas concentration in the upper corner was up to 1.1%, which failed to meet the gas control standards on the mine’s panel. However, the maximum gas concentration in the combined drainage was reduced from 1.1% to 0.6%, which indicates that the technology can greatly reduce gas concentration, but there is still a gap from the mine’s gas control standard. Therefore, the impacts of the lengths of pipelines buried in different goafs on the gas drainage effect in the goaf were studied, and it was concluded that the reasonable length of pipelines buried in the goaf under the geological conditions was 20 m. This technology not only solves the problem of gas overrun in the panel but also realizes the utilization of gas resources in the goaf. The research results are of guiding significance for pipeline laying and the drainage technology in the upper corners on the U-shaped ventilation panel.

scholarly journals Deformation Mechanism and Control of the Surrounding Rock during Gob-Side Entry Driving along Deeply Fully Mechanized Caving Island Working Face

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Fei Liu ◽  
Yongsheng Han
Keyword(s):  
Deformation Mechanism ◽  
Industrial Test ◽  
Surrounding Rock ◽  
Practical Significance ◽  
Efficient Production ◽  
Deformation Characteristics ◽  
The West ◽  
Deformation Control ◽  
Working Face ◽  
And Control

The deformation control of the surrounding rock during gob-side entry driving along deeply fully mechanized caving island working face is one of the main bottlenecks affecting the successful and efficient production in modern mining. The prior ordinary fully mechanized caving theories have been difficult in ensuring the safe and efficient mining along island working face during gob-side entry driving under the complex conditions in the west. Therefore, it is of great theoretical and practical significance to carry out the research on the deformation mechanism and control of the surrounding rock during gob-side entry driving along deeply fully mechanized caving island working face. This paper, by means of experimental research, theoretical analysis, numerical calculation, and field industrial test, systemically researched the deformation characteristics of the surrounding rock and the law of strata behaviors during gob-side entry driving along deeply fully mechanized caving island working face.

scholarly journals Study on the Bearing Characteristics and Application of the Filling Body in Original Roadway Filling and Nonpillar Driving

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Wenbao Shi ◽  
Yan Li ◽  
Jucai Chang
Keyword(s):  
Water Content ◽  
Coal Mining ◽  
High Water ◽  
High Water Content ◽  
Working Face ◽  
Geological Conditions ◽  
Analysis Laboratory ◽  
The Stability ◽  
And Control

Abstract Original roadway filling and nonpillar driving can effectively solve the difficulty facing mining replacement in the stope of deep mines. As the bearing characteristics of the filling body in the original roadway play a crucial role in the structural stability of the overlying strata, with the recovery and geological conditions of 62210 working face in Xinzhuangzi Coal Mine, Huainan Mining Group, China, as the background, this study analyzed the stability characteristics of the filling body in the original roadway through comprehensive research methods of theoretical analysis, laboratory tests, and onsite monitoring. The results disclose that the filling body in the original roadway should boost early strength, strong bearing capacity, and long-term weakening. When the water-cement ratios are 1 : 1, 1.5 : 1, 2 : 1, 2.5 : 1, and 3 : 1, the strengths of the filling body are 1.12 MPa, 0.93 MPa, 0.57 MPa, 0.33 MPa, and 0.21 MPa at 2 h and 5.63 MPa, 4.66 MPa, 2.87 MPa, 1.65 MPa, and 1.02 MPa at 48 h, respectively. The strengths surge by 5 times within 2 d on the whole and reach the maximum at about 7 d, i.e., 8.12 MPa, 6.91 MPa, 6.60 MPa, 3.95 MPa, and 2.20 MPa, respectively. As time goes, the water content of the filling body gradually decreases and the compressive strength plunges. This demonstrates that the rapid solidification material with a high water content can satisfy the requirements of the bearing characteristics of the original roadway filling body. With reference to numerical simulation and the data monitored onsite, it can be known that the filling body in the original roadway can support the roof effectively and control the surrounding rock deformation of newly excavated roadways in the lower section. The research results provide theoretical guidance for coal mining under similar geological conditions and serve as reference for safe and efficient coal mining.

Study on Theoretical Analysis and Numerical Simulation of Smoke Flow during Gas Explosion

2010 ◽  
Vol 29-32 ◽  
pp. 125-131
Author(s):  
Zhi Ming Qu
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
Coal Dust ◽  
Treatment Plan ◽  
Ventilation System ◽  
Gas Explosion ◽  
Gas Concentration ◽  
Working Face ◽  
Hazardous Area ◽  
Secondary Disasters

In most cases, high gas concentration and oxygen consumption result in severe hypoxia after explosion. When the ventilation system is damaged, the air volume will be re-distributed so that explosion region is lack of oxygen. However, under mechanical ventilation and self-diffusion, the high temperature and toxic and harmful gases will constantly spread downwind of the roadway or certain areas, which threatens substations, winch room and workers’ escape. If the hot gas meets with gas concentration overrun areas or the coal dust explosion hazardous area, secondary disasters such as fire or explosion may be caused. Numerical simulation shows that high temperature, toxic and harmful gas will be disseminated. In conclusion, measures must be taken to withdraw the workers and to restore ventilation to prevent secondary disasters. If the gas explosion power is increased, the safety nearby working face would be threatened. To control and reduce the extent of gas explosion hazards and losses, a reasonable gas explosion disaster prevention and treatment plan should be established.

Internet of Things (IoT) is Smart Homes and the Risks

2019 ◽  
pp. 1-4
Keyword(s):  
Continuous Monitoring ◽  
Human Person ◽  
Advanced Technology ◽  
Efficient Production ◽  
Technological Evolution ◽  
Technological Revolution ◽  
Full Control ◽  
Control Production ◽  
Smart Technologies ◽  
And Control

Undoubtedly is a technological revolution that has certainly focused on the interest of software development companies, companies of IT, hardware design, networks and artificial intelligence. A technological revolution that started a few years ago and has evolved rapidly, thanks to the technological evolution of IT and networks. It is a combination of many communication protocols, sensors and other intelligent technologies, the correlation between smart technologies, networks and services that all together complete processes in order to achieve the result for which they were installed. In advanced technology countries, both simple users and industry use IoT where sensors are simplified and automated at home and in industry, there is continuous monitoring, control and prediction of product failure for the benefit of efficient production of high quality products and control production at each stage of product processing / production. Someone could well think and say that all this is fantastic and that we have solved the problem of organization, easy life without further thoughts and worries since everything is done automatically.An IoT in an intelligent house could literally regulate everything, using sensors and appropriate software could talk with a human person, as well as someone could appropriately entice all that security and literally take full control of the premises of a home with consequences from minimal to catastrophic including the complete destruction of a home.

scholarly journals The Investigation of Decontamination Effects of Ozone Gas on Microbial Load and Essential Oil of Several Medicinal Plants

2013 ◽  
Vol 5 (1) ◽  
pp. 34-38 ◽  
Author(s):  
Razieh VALI ASILL ◽  
Majid AZIZI ◽  
Maasome BAHREINI ◽  
Hossein AROUIEE
Keyword(s):  
Medicinal Plants ◽  
Essential Oil ◽  
Block Design ◽  
Microbial Load ◽  
Mentha Piperita ◽  
Gas Treatment ◽  
Zataria Multiflora ◽  
Gas Concentration ◽  
Mold And Yeast ◽  
And Control

Today, Ozone as a disinfectant method, without putting on the harmful effects on human and plant products, it is alternative common methods for disinfection of plant material. The research as a factorial experiment was conducted on the basis of randomized complete block design with three replications and the effects of Ozone gas on decreasing the microbial load of some important medicinal plants include: Peppermint (Mentha piperita), Summer savory (Satureja hortensis), Indian valerian(Valeriana wallichii), Meliss (Melissa officinalis) and Iranian thyme (Zataria multiflora) were investigated. Medicinal plants leaves were treated with Ozone gas concentration 0.3, 0.6 and 0.9 ml/L at times of 10 and 30 then total count, coliform and mold and yeast of the samples were studied. The result showed that Ozone gas decreases microbial load of medicinal plants samples. But Ozone gas and Ozone gas in medicinal plants interaction effect had no effect on essential oil content. The lowest and the highest of microbial load were detected in samples treated with concentration of 0.9 ml/L of Ozone gas and control respectively. The highest and the lowest of microbial load were observed in Iranian thyme and Indian valerian respectively. Also result showed that Ozone gas treatment for 30 min had the greatest of effect in reducing the microbial load and 0.9 ml/L Ozone gas concentration had the lowest of microbial load. Results of this survey reflect that the use of Ozone as a method of disinfection for medicinal plants is a decontamination.

A study on source identification of gas explosion in coal mines based on gas concentration

Fuel ◽  
2021 ◽  
Vol 290 ◽  
pp. 120053
Author(s):  
Baiwei Lei ◽  
Chenguang Zhao ◽  
Binbin He ◽  
Bing Wu
Keyword(s):  
Source Identification ◽  
Coal Mines ◽  
Gas Explosion ◽  
Gas Concentration
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