Analysis on the Stability of Hydraulic Support in Great Tilt Angle Mining Face

2014 ◽  
Vol 556-562 ◽  
pp. 519-522
Author(s):  
Qing Qing Huang ◽  
Qiu Jie Zhang
Keyword(s):  
Tilt Angle ◽  
Mining Industry ◽  
Static Force ◽  
Hydraulic Support ◽  
Working Surface ◽  
Mining Face ◽  
The Stability

The hydraulic support is mainly used in roadway and workplace for supporting and protecting in mining industry. The hydraulic support would appear the situation of declining, dumping and crowding on greater tilt angle mining face, these will threat the safety of the workplace, the safety of mining face is the key to the safety in production. This paper analyzes the reasons of declining, dumping in static force, gives respectively the angle range of working surface hydraulic support declining and dumping, proposes some relevant measures of the hydraulic support declining and dumping.

Simulation Study on the Stability of Mining Thin Flat-Grade Iron Ore Body with Hydraulic Support Longwall Method

2012 ◽  
Vol 170-173 ◽  
pp. 3706-3710
Author(s):  
Shu Guo Zhao ◽  
Wei Dong Song ◽  
Wen Bin Xu ◽  
Huan Hu Song
Keyword(s):  
Stress Concentration ◽  
Simulation Method ◽  
Small Range ◽  
Rock Stress ◽  
Coal Face ◽  
Hydraulic Support ◽  
Plastic Zones ◽  
Concentration Degree ◽  
Mining Face ◽  
The Stability

This paper proposed hydraulic support longwall method for mining glacis thin orebody. The DaZhuang ore section of Guandian Ore Mining whose orebody in the line of -8＇—-16＇was chosen as the research object. It applied the FLAC numerical simulation method to study the changes of surrounding rock stress in the mining face, displacement and plastic zones, and put forward the changing law of the rock stress, displacement and plastic zones in the mining process. Besides, it proved that the mechanical condition of the roofs changed in different stages. When the distance between pillar and mining face was in the range of 4m—8m, the state was relatively stable, and the pillar and surrounding rocks were in small range of shearing and tensile yield. When distance was 12m, the roof suffered from compression. When it was up to 16m, the roof and bottom rock displayed tension. However，the appreciation of stress changed very little at different stages. The stress concentration circle formed between the top and bottom of the pillar, and the unloading appeared in the top and bottom gap. The nearer to the coal face, the more powerful of stress concentration, and the influence of pillar’s position on stress concentration degree is very little in the front of coal face. The structure would be in stable equilibrium when the distance between single stent and coal face is 12m. In such circumstances, the security of roof would be improved if more stents are added

The Meniscus Instability of a Thin Liquid Film

1988 ◽  
Vol 55 (4) ◽  
pp. 975-980 ◽  
Author(s):  
H. Koguchi ◽  
M. Okada ◽  
K. Tamura
Keyword(s):  
Thin Film ◽  
Analytical Solution ◽  
Liquid Film ◽  
Tilt Angle ◽  
Stability Criterion ◽  
Thin Liquid Film ◽  
Normal Direction ◽  
Wave Number ◽  
The Stability ◽  
Maximum Amplification

This paper reports on the instability for the meniscus of a thin film of a very viscous liquid between two tilted plates, which are separated at a constant speed with a tilt angle in the normal direction of the plates. The disturbances on the meniscus moving with movement of the plates are examined experimentally and theoretically. The disturbances are started when the velocity of movement of the plates exceeds a critical one. The wavelength of the disturbances is measured by using a VTR. The instability of the meniscus is studied theoretically using the linearized perturbation method. A simple and complete analytical solution yields both a stability criterion and the wave number for a linear thickness geometry. These results compared with experiments for the instability show the validity of the stability criterion and the best agreement is obtained with the wave number of maximum amplification.

scholarly journals Mechanical Modeling of Roof Fracture Instability Mechanism and Its Control in Top-Coal Caving Mining under Thin Topsoil of Shallow Coal Seam

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Peilin Gong ◽  
Tong Zhao ◽  
Kaan Yetilmezsoy ◽  
Kang Yi
Keyword(s):  
Coal Seam ◽  
Mechanical Model ◽  
Main Roof ◽  
Stability Control ◽  
Hydraulic Support ◽  
Rock Stability ◽  
Shallow Coal Seam ◽  
Minimum Height ◽  
The Stability ◽  
Working Resistance

This study aimed to explore the safe and efficient top-coal caving mining under thin topsoil of shallow coal seam (SCS) and realize the optimization of hydraulic support. Numerical simulation and theoretical analysis were used to reveal the stress distribution of the topsoil, the structure characteristics of the main roof blocks, and the development of the roof subsidence convergence. Step subsidence of the initial fractured main roof after sliding destabilization frequently existed, which seriously threatened the safety of the hydraulic supports. Hence, a mechanical model of the main roof blocks, where the topsoil thickness was less than the minimum height of the unloading arch, was established, and the mechanical criterion of the stability was achieved. The working resistance of the hydraulic support was calculated, and the reasonable type was optimized so as to avoid crushing accident. Findings of the present analysis indicated that the hydraulic support optimization was mainly affected by fractured main roof blocks during the first weighting. According to the block stability mechanical model based on Mohr–Coulomb criterion, the required working resistance and the supporting intensity were determined as 4899 kN and 0.58 MPa, respectively. The ZZF5200/19/32S low-position top-coal caving hydraulic support was selected for the studied mine and support-surrounding rock stability control of thin-topsoil SCS could be achieved without crushing accident.

scholarly journals A Controller Combining Positive Velocity Feedback with Negative Angle Feedback for a Two-Wheeled Robot

2015 ◽  
Vol 15 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Lingyan Hu ◽  
Henry Leung Ieee ◽  
Shaoping Xu ◽  
Hua Zhang
Keyword(s):  
Nonlinear System ◽  
Negative Feedback ◽  
Tilt Angle ◽  
Positive Feedback ◽  
Pid Controller ◽  
System Stability ◽  
Velocity Control ◽  
Velocity Feedback ◽  
Wheeled Robot ◽  
The Stability

Abstract The two-wheeled robot is a nonlinear system of multi-variables, higherorder and strong coupling. This paper presented a PID Controller with Double Loops (PCDL) to control the tilt angle and velocity of a two-wheeled robot. The angle controller is the regular negative feedback, while the velocity control is the positive feedback. The Double Loops work cooperatively to endow the system with strong anti-interference ability. The stability of the whole system is analyzed and the criterion of the system stability is developed. The simulation and experiments showed that the two-wheeled robot can self-balance and move at an expected velocity and the system has strong anti-interference ability.

scholarly journals Development of kaolin production, reserves and processing in the Czech Republic in 1999–2015

2017 ◽  
Vol 33 (3) ◽  
pp. 121-142 ◽  
Author(s):  
Jaromír Starý ◽  
František Pticen ◽  
Jakub Jirásek ◽  
Martin Sivek
Keyword(s):  
Czech Republic ◽  
Mining Industry ◽  
Silica Sand ◽  
Industrial Minerals ◽  
Growth Trend ◽  
The Czech Republic ◽  
Mine Production ◽  
Export Restrictions ◽  
The Government ◽  
The Stability

Abstract This paper aims to characterize and interpret the trends in reserves, resources, and in the mine production of crude kaolin and output of beneficiated kaolin between 1999 and 2015 in the Czech Republic. With nearly 1.2 billion tonnes of total resources, kaolin belongs to the key industrial minerals of the Czech Republic. With an annual output of about 3 to 4 million tonnes of crude kaolin and of around 0.6 million tonnes of beneficiated kaolin, the Czech Republic ranks among the top European and world kaolin producers. Mine production of crude kaolin has been relatively stable since 1997, while the output of beneficiated kaolin has been increasing gradually during the same period. The increased production and yield of beneficiated kaolin resulted from the use of progressive methods in kaolin processing, primarily high-intensity electromagnetic separation. The positive growth trend was not a reflection of the stability of the extractive sector and domestic industry, but it was the result of a pro-export orientation. The amount and share of exports are continuously increasing and constitute 80% of the entire kaolin production sector at the present time. The only exception occurred in 2005-2008, when exports declined by one-half as a result of the government´s export restrictions. The results of analyses were not optimistic for the Czech economy and indicated a sharp downturn in the domestic mining industry. Moreover, a similar situation exists in the case of other essential industrial minerals such as feldspar, clays, and silica sand.

scholarly journals Meeting Energy Demands Through Mining

2021 ◽  
Vol 1 (2) ◽  
pp. 1-13
Author(s):  
Amosu C. O.* ◽  
Keyword(s):  
Electric Power ◽  
Fossil Fuels ◽  
Mining Industry ◽  
Energy Applications ◽  
Energy Demands ◽  
The Stability

The Mineral and Mining industry is a huge energy requiring sector which demands connections to a viable electric power origin and reference. With the upsurge of these mineral requests and decreasing valued grades of ores, energy aspiration is approximated to sky-rocket to 36% by the year 2035. It is even projected to accelerate geometrically from the fact that sophistication and powering of the mine locations speeds up the stability into the necessity of energy applications and its requirements derived from fossil fuels utilized to generate electricity. This paper discusses other fossilized fuel-based materials for generation of electricity

scholarly journals Determination of Reasonable Width of Filling Body for Gob-Side Entry Retaining in Mining Face With Large Cutting Height

2021 ◽  
Author(s):  
Shijiang Pu ◽  
Gui yi Wu ◽  
Qinzhi Liu ◽  
Yuliang Wang ◽  
Qiang Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Mechanical Model ◽  
Vertical Displacement ◽  
Vertical Stress ◽  
Body Width ◽  
Minimum Width ◽  
Mining Face ◽  
The Stability ◽  
Cutting Height ◽  
Two Sides

Abstract When gob-side entry retaining is adopted in mining face with large cutting height, due to large stope space, strong dynamic pressure and other reasons, the filling body is usually broken and unstable due to improper width of filling body, and the stability of surrounding rock of roadway is poor. Therefore, this paper will take Shaqu mine as the engineering background to study the reasonable filling body width of gob-side entry retaining in mining face with large cutting height. Firstly, the stability factors of gob-side entry retaining in mining face with large cutting height are analyzed, and the mechanical model of bearing structure of gob-side entry retaining is established based on the lateral pressure and overlying load of filling body, and the reasonable width of filling body is obtained quantitatively; Numerical simulation is used to analyze the evolution of vertical stress, vertical displacement and plastic zone of working face with the change of filling body width. Finally, combined with the deformation observation results of 24207 gob-side entry retaining roof, two sides and filling body, the rationality of filling body width is verified. The results show that: the setting of the width and strength of the filling body plays an important role in the stability of gob-side entry retaining. According to the mechanical model, the minimum width of the filling body is 2.2m in the lateral direction and 3.9m in the vertical direction; Numerical simulation shows that when the width of filling body is too small, with the increase of filling body width, the vertical stress of filling body increases gradually. When the width of filling body reaches a certain value, the vertical stress decreases with the increase of width, and the stress concentration area will change from symmetrical type to eccentric load type, from the middle of filling body to the side of filling body near gob. If the width of the filling body is too small, the filling body will be too broken to bear the load, resulting in too small vertical stress and too large vertical displacement of the roadway roof. The larger the width of the filling body is, the greater the cutting resistance is, the more timely the side roof of the gob can be cut off, the less the stress of the roadway and the filling body, and the more stable the retained roadway is. Finally, through the observation of 24207 gob-side entry retaining, the total deformation of two sides and roof and floor of roadway tends to be stable after 665mm and 597mm respectively. The roof of roadway does not appear severe subsidence and obvious cracking, and the floor does not appear too large floor heave. The effect of roadway retaining is good, which indicates that 4m support can meet the needs of practical engineering.

Mechanical stability of black spruce in the clay belt region of northern Ontario

1987 ◽  
Vol 17 (9) ◽  
pp. 1080-1091 ◽  
Author(s):  
V. G. Smith ◽  
M. Watts ◽  
D. F. James
Keyword(s):  
Mechanical Stability ◽  
Black Spruce ◽  
Stand Density ◽  
Tree Height ◽  
Static Force ◽  
Northern Ontario ◽  
Wind Speeds ◽  
Spruce Stands ◽  
Stand Height ◽  
The Stability

Black spruce (Piceamariana (Mill.) B.S.P.) is an important pulpwood species that grows on peatland sites in the clay belt region of northern Ontario. The mechanical stability of spruce found on these sites is crucial in determining how tall a stand can grow before losses due to windthrow become excessive. In this study, the stability of a sample of 58 black spruce trees, in stands of various height and density classes, was measured by winching them over and determining their critical turning moment. Regression analysis was used to express critical turning moment as a function of tree height, dominant stand height, and stand stocking. An analysis was carried out to estimate turning moments due to static wind action on the sample trees and predicting the wind speeds required to produce the static force needed to cause windthrow. A comparison of the measured critical turning moments to the estimated wind-generated critical turning moments was used to identify the wind speeds that have enough static force to cause windthrow. A table of critical wind speeds, based on a reference wind, is given for black spruce stands of various heights and densities. Based on these wind speeds and winds associated with periodic storms, black spruce stands can be expected to become susceptible to windthrow once dominant stand height reaches 20 to 21 m. Stand stability increases with stand density owing to the greater ability of dense stands to dissipate incoming winds and the added stability of interlocking root systems. These results suggest that the black spruce stands growing on peatland sites in the clay belt should be harvested before dominant stand height reaches a maximum of 20 to 21 m to avoid excessive losses due to windthrow.

PROBABILISTIC BEHAVIOR OF JOINT FORCES IN MECHANISMS

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Boštjan Harl ◽  
Marko Kegl ◽  
Nenad Gubeljak ◽  
Dejan Dinevski
Keyword(s):  
Mining Industry ◽  
Hydraulic Support ◽  
Kinematic Chains ◽  
Taylor Approximation ◽  
The Monte Carlo Method ◽  
Joint Forces ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Joint Reaction ◽  
Actual Part

This paper discusses the influence of the clearance in joints on the joint reaction forces in mechanisms. By using mathematical programing, the optimal parameters of kinematic chains can be efficiently obtained by using the deterministic approach. However, the situation becomes more sophisticated if random effects of tolerances of the arm lengths and the random pin positions have to be considered. In this work the influence of clearances on joint forces is calculated by using the Taylor approximation and the Monte Carlo method. Using the two methods was necessary, because the Taylor approximation usually yields satisfying results only for small values of clearances and for this reason it makes sense to compute the required quantities also by another independent method. The implementation of the model is illustrated with two examples. The first example considers a closed loop chain, representing a four-bar mechanism being an actual part of a hydraulic support, employed in mining industry. The hydraulic support must fulfill some requirements so it’s very important to have influence of clearances on joint forces in control. The second example considers joint reaction forces of car wiper mechanism. It will be shown, that the clearance in joints have some influence on the joint reaction forces.

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