scholarly journals Mechanism and Control of Cable Breakage in a Roadway with Thick Top Coal in a Rockburst Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ying Xu ◽  
Xiekang Zhou ◽  
Weimei Gong
Keyword(s):  
Simulation Method ◽  
Pressure Control ◽  
Surrounding Rock ◽  
Mine Pressure ◽  
Energy Evolution ◽  
Evolution Law ◽  
Roof Caving ◽  
Bolt Failure ◽  
Breakage Mechanism ◽  
And Control

Because top coal is not stable, a roadway with thick top coal often appears to mine pressure problems, such as bolt failure, cable breakage, and roof caving. In particular, these problems are more serious in rockburst mines. Based on a cable breakage case of No. 3 roadway in Xingcun coal mine, the paper analyzed the stress and elastic energy evolution law of surrounding rock and stress state of cable in the 3# roadway by means of the numerical simulation method. Thus, the cable breakage mechanism of the roadway with thick top coal in rockburst mine was revealed. Then, because surrounding rock grouting can reduce the stress concentration of surrounding rock and cable, surrounding rock grouting technology was proposed as control technology of cable breakage. Finally, parameters of surrounding rock grouting were designed and applied in the No. 3 roadway. The field results showed that surrounding rock grouting technology can be one of the solutions for cable breakage of roadway with thick top coal in rockburst mine. The research results of this paper can provide certain theoretical and practical value for mine pressure control of roadway.

scholarly journals Strata behavior and control strategy of backfilling collaborate with caving fully-mechanized mining

2020 ◽  
Vol 12 (1) ◽  
pp. 703-717
Author(s):  
Yin Wei ◽  
Wang Jiaqi ◽  
Bai Xiaomin ◽  
Sun Wenjie ◽  
Zhou Zheyuan
Keyword(s):  
Numerical Simulation ◽  
Control Strategy ◽  
Three Dimensional ◽  
Simulation Method ◽  
Mine Pressure ◽  
Hydraulic Support ◽  
Transition Area ◽  
Pressure Concentration ◽  
Strata Behavior ◽  
And Control

AbstractThis article analyzes the technical difficulties in full-section backfill mining and briefly introduces the technical principle and advantages of backfilling combined with caving fully mechanized mining (BCCFM). To reveal the strata behavior law of the BCCFM workface, this work establishes a three-dimensional numerical model and designs a simulation method by dynamically updating the modulus parameter of the filling body. By the analysis of numerical simulation, the following conclusions about strata behavior of the BCCFM workface were drawn. (1) The strata behavior of the BCCFM workface shows significant nonsymmetrical characteristics, and the pressure in the caving section is higher than that in the backfilling section. φ has the greatest influence on the backfilling section and the least influence on the caving section. C has a significant influence on the range of abutment pressure in the backfilling section. (2) There exits the transition area with strong mine pressure of the BCCFM workface. φ and C have significant effect on the degree of pressure concentration but little effect on the influence range of strong mine pressure in the transition area. (3) Under different conditions, the influence range of strong mine pressure is all less than 6 m. This article puts forward a control strategy of mine pressure in the transition area, which is appropriately improving the strength of the transition hydraulic support within the influence range (6 m) in the transition area according to the pressure concentration coefficient. The field measurement value of Ji15-31010 workface was consistent with numerical simulation, which verifies the reliability of control strategy of the BCCFM workface.

The Mine Pressure Management and Control Fully-Mechanized Coal Working Face Roof and Floor of Soft Strata

2014 ◽  
Vol 962-965 ◽  
pp. 1123-1126 ◽  
Author(s):  
Ru Bin Liu ◽  
Hai Yun Zhang
Keyword(s):  
Coal Seam ◽  
Pressure Control ◽  
Control Measures ◽  
Mine Pressure ◽  
Pressure Management ◽  
Working Face ◽  
Production Practice ◽  
And Control

The “three volume” and the characteristics of deformation and damage of coal seam were observed and analyzed, the appropriate mine pressure control measures were proposed and put into production practice.

Numerical Simulation of Blasting-Induced Damage in Grouting Curtain of Sandstone Aquifer for Vertical Shaft

2015 ◽  
Vol 723 ◽  
pp. 271-278
Author(s):  
Yu Liang Zhou ◽  
Dong Feng Yuan ◽  
Jun Zheng ◽  
Hua Wang
Keyword(s):  
Numerical Simulation ◽  
Prevention And Control ◽  
Damage Zone ◽  
Surrounding Rock ◽  
Damage Effect ◽  
Vertical Shaft ◽  
Control Methods ◽  
Sandstone Aquifer ◽  
And Control ◽  
Dynamic Damage

To provide a theoretical basis for water prevention and control methods and reasonable supporting techniques for vertical shaft, and to ensure the shaft construction to pass the sandstone aquifer safely and rapidly, numerical simulation using dynamic damage constitutive model, which was a user-defined constitutive modules in FLAC3D, a lagrangian analysis code in three dimensions, has been applied to investigate the dynamic damage effect in the surrounding rock of the grouting curtain near the driving working face for vertical shaft excavated by blasting. The results indicate that the distribution of the damage zone in the surrounding rock of the shaft, which decreases the effective thickness of the grouting curtain, was like a ellip-se, and that the depth of the damage zone in the surrounding rock of the shaft grouting curtain is fewer than that of the driving face floor. It can be concluded that the centre part of the driving face floor, especially the cutting hole zones, and the shaft wall in the greater horizontal stress side are the " key parts " for shaft water prevention and control methods.

scholarly journals Dynamic Analysis and Control of an Automatic Transmission for Start-Stop Function and Efficiency Improvement

2015 ◽  
Vol 2015 ◽  
pp. 1-13
Author(s):  
Yang Liu ◽  
Shuhan Wang ◽  
Peng Dong ◽  
Xiangyang Xu
Keyword(s):  
Control Strategies ◽  
Automatic Transmission ◽  
Simulation Method ◽  
Transmission Efficiency ◽  
The Novel ◽  
Test Results ◽  
Test Environment ◽  
Pump System ◽  
Oil Pump ◽  
And Control

An electric oil pump (EOP) was integrated into the hydraulic system and an automatic transmission (AT) mechanical oil pump (MOP) was downsized. These processes were performed to combine a start-stop function with the AT and further improve the transmission efficiency. Furthermore, this study established a dynamics model of power loss and leakage of an 8-speed AT; a flow-based control algorithm of the EOP was then developed to realize the start-stop function and support the MOP to meet the flow requirement of the system. Based on a driving simulation method, sizes of the MOP and EOP that ensured optimal fuel economy were selected. A control strategy for the starting clutch was also developed to minimize the starting delay of the test vehicle. A test environment on a rig and prototype vehicle was established to verify the feasibility of the proposed control strategies. The test results indicated that the transmission functioned favorably with the novel two-pump system presented, and a quick and smooth starting performance was achieved when the engine was restarted. The findings in this study are extremely valuable for forward designs of an AT for realizing start-stop function and improving efficiency.

scholarly journals Stability Control of Deep Coal Roadway under the Pressure Relief Effect of Adjacent Roadway with Large Deformation: A Case Study

2021 ◽  
Vol 13 (8) ◽  
pp. 4412
Author(s):  
Houqiang Yang ◽  
Nong Zhang ◽  
Changliang Han ◽  
Changlun Sun ◽  
Guanghui Song ◽  
...  
Keyword(s):  
Large Deformation ◽  
Coal Mine ◽  
High Stress ◽  
Surrounding Rock ◽  
Western China ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Coal Roadway ◽  
And Control ◽  
Relief Effect

High-efficiency maintenance and control of the deep coal roadway surrounding rock stability is a reliable guarantee for sustainable development of a coal mine. However, it is difficult to control the stability of a roadway that locates near a roadway with large deformation. With return air roadway 21201 (RAR 21201) in Hulusu coal mine as the research background, in situ investigation, theoretical analysis, numerical simulation, and engineering practice were carried out to study pressure relief effect on the surrounding rock after the severe deformation of the roadway. Besides, the feasibility of excavating a new roadway near this damaged one by means of pressure relief effect is also discussed. Results showed that after the strong mining roadway suffered huge loose deformation, the space inside shrank so violently that surrounding rock released high stress to a large extent, which formed certain pressure relief effect on the rock. Through excavating a new roadway near this deformed one, the new roadway could obtain a relative low stress environment with the help of the pressure relief effect, which is beneficial for maintenance and control of itself. Equal row spacing double-bearing ring support technology is proposed and carried out. Engineering practice indicates that the new excavated roadway escaped from possible separation fracture in the roof anchoring range, and the surrounding rock deformation of the new roadway is well controlled, which verifies the pressure relief effect mentioned. This paper provides a reference for scientific mining under the condition of deep buried and high stress mining in western China.

Abstract 15595: Missed Targets: United States Trends in Hypertension Prevalence, Control, and Treatment 2005-2018

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Rahul Aggarwal ◽  
Nicholas Chiu ◽  
Rishi Wadhera ◽  
Changyu Shen ◽  
Robert W Yeh ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Temporal Trends ◽  
Cost Effective ◽  
Pressure Control ◽  
Healthy People ◽  
Sensitivity Analyses ◽  
Base Case ◽  
Improve Blood Pressure Control ◽  
Hypertension Prevalence ◽  
And Control

Introduction: Hypertension is a major risk factor for cardiovascular disease. The US government, through the Healthy People Initiative 2020, set targets to improve hypertension prevalence and treatment rates in US adults by a relative 10% from 2005 to 2020, and increase control rates by a relative 40%. We examined US progress towards this goal from 2005-2018. Methods: We analyzed data from 38,876 non-pregnant US adults from the NHANES 2005-2018 surveys to determine nationally representative estimates of hypertension prevalence, treatment rates, and control. Temporal trends in hypertension prevalence, treatment, and control were assessed using weighted linear regression after age adjustment to the 2000 US census (per the Healthy People Initiative approach). In the base case, we defined hypertension as blood pressure >140/90 or on an antihypertensive; we used the ACC/AHA definition of blood pressure >130/80 in sensitivity analyses. Results: In 2017-2018, 34.3% (±1.7) of US adults had hypertension, of these 69.7% (±1.5) were on treatment, and 43.7% (±1.6) were controlled. After age-adjustment, no statistically significant changes in hypertension prevalence, treatment rates, or control were observed from 2005-2018 (p for trend 0.91, ,0.98, 0.66, Figure 1). In sensitivity analyses, applying the ACC/AHA definition increased the estimated prevalence of hypertension during the period, but trends in prevalence remained unchanged. Conclusions: There has been no material progress in reducing the prevalence of hypertension or improving rates of treatment and control from 2005 to 2018. As planning is underway for Healthy People Initiative 2030, setting of hypertension targets must be accompanied with investments in cost-effective, scalable programs to improve blood pressure control nationwide, with a focus on high-risk populations.

scholarly journals Nanotechnology: A Journey towards Finding Solutions

2015 ◽  
Vol 5 (1) ◽  
pp. 61
Author(s):  
Satya Pal Singh
Keyword(s):  
Health And Safety ◽  
Functional Materials ◽  
Simulation Method ◽  
Industrial Applications ◽  
Policy Makers ◽  
Advance Research ◽  
American Physical ◽  
Richard Feynman ◽  
And Control ◽  
Thin Film Magnetism

<p class="1Body">Nanotechnology is the understanding and control of matter at the diemnsions ranging between 1-100 nm. One nanometer is one billionth of a meter. Nanotechnology involves manipulation of atoms, imaging, measuring and modelling at nano scale. Its potentials were first highlighted by Richard Feynman in the American Physical Scociety meeting in 1959. Though, he did not coin the world nanotechnology himself but he explored the possiblities of functional materials at the bottom of the scale. In last two decades this technology has been commercialized to great extent and gaining importance day by day influencing the economies of different countries and henceforth enforcing the policy makers to address the issues like environment, health and safety. Governments are regularisaing and monitoring its research, uses, applications and technology transfer which includes intelluctaul property rights. This paper addresses the dimensions and trends of nanotechnology covering economic aspects. The paper is focussed on the changes in the functional properties of nanomaterials as physical, chemical, optical, electronic, electrical, magnetic etc. in comparision to those of the bulk of material. It has been discussed how the basic and advance research in nanoscience could be explotiedfor making technologies for its commercial and industrial applications for the benefit and safety of the soceity. Thin film magnetism is demonstrated using Monte Carlo simulation method. Experimental synthesisof some of thenanorods and qunatum dots are also discussed.</p>

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