Study and Application on the Parameters of Gob-Side Entry Retaining in Thin Seam with Limestone Roof

2011 ◽  
Vol 361-363 ◽  
pp. 193-197 ◽  
Author(s):  
Zhong Ping Guo ◽  
Jia Li Qi ◽  
Hui Qiang Duan
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Coal Mine ◽  
Field Observation ◽  
Mechanical Model ◽  
Technical Parameters ◽  
Coal Recovery ◽  
Safe Production ◽  
The Face ◽  
Thin Seam

The gob-side entry retaining technology can be used to not only solve the problem of intensity in successive mining but also reduce the 10,000 tons' drivage rate and improve the coal recovery. Based on the established roof cutting mechanical model, the method of numerical simulation is used to determine the technical parameters of gob-side entry retaining in one coal mine. The reduction in cross-section of the roadway is 10.8% according to the field observation, which shows that the gob-side entry retaining has obtained preferable results and fulfilled the demand of safe production in the face.

Optimization and Application of High Production and High Efficiency Mining Parameters of Fully Mechanized Caving Face

2011 ◽  
Vol 361-363 ◽  
pp. 198-203
Author(s):  
Zhong Ping Guo ◽  
Shan Chao Hu ◽  
Zhi Gao Zhang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Analysis ◽  
High Efficiency ◽  
Physical Simulation ◽  
Coal Recovery ◽  
The Face ◽  
High Production ◽  
Cutting Height

The size of the fully mechanized caving face is optimized by theoretical analysis and the dip length of the face is determined as 260m. With the method of numerical simulation, the reasonable cutting height of the face is determined as 3.5m and the caving method is determined as one round caving in order. The physical simulation is used to analyze the caving effects under different drawing intervals and the reasonable drawing interval is determined as 0.8m. The coal recovery is improved by 3.43% after the parameters are applied in field and the goal of high production and high efficiency of the mine has been achieved.

Rock Bolting Numerical Simulation Research and Application of the Face Breakthough

2011 ◽  
Vol 105-107 ◽  
pp. 2239-2243
Author(s):  
You Lin Xu ◽  
Hui Zhang ◽  
Wei Zheng
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Rock Strength ◽  
Test Methods ◽  
Strength Test ◽  
Simulation Research ◽  
Rock Bolting ◽  
Mine Roadway ◽  
The Face ◽  
Coal Rock

This paper analyzes the importance of rock bolting in coal mining, and the difficult of using rock bolting in breakthough with the affect of mining, adopt hydraulic fracturing and coal-rock mass strength test methods to test the seam stress and rock strength. Make the numerical simulation of break though bolting solutions in coal mine roadway by using FLAC3D software, simulate the different distributions of pre-stressed in coal-rock with three situations, the same raw distance but different space, the same space but different raw distance, impose different preload on the roof anchor in the rock bolting of mine roadway breakthough. Then determine a reasonable bolting solution of coal mine roadway according to the case of prestressed in coal-rock.

Numerical Simulation Study on Combined Supporting Scheme of Bolts and Anchor Cable

2014 ◽  
Vol 638-640 ◽  
pp. 898-903
Author(s):  
Wen Cai Wang ◽  
Wen Bin Wei ◽  
Ling Wang
Keyword(s):  
Numerical Simulation ◽  
Simulation Study ◽  
Coal Mine ◽  
Simulation Software ◽  
Practical Application ◽  
Anchor Cable ◽  
Result Show ◽  
The Face

Aiming at the face roadway 22109 of Cuncaota coal mine, using FLAC3Dnumerical simulation software, 19 of 5 groups about bolt and anchor combined support schemes were analysed and compared, and the reasonable scheme of φ18×2000mm thread steel bolt and φ17.8×6500mm anchor cable combined support was obtained. Support result of this scheme was analysed with FLAC3Dsoftware, the result show that this scheme can support the roadway effectively. Practical application show that this scheme can achieve the security, economical and effective support result, and can be used in this type of roadway.

Effect Analysis of Nitrogen Injection on the Variation of “Oxidation Zone” in Coal Mine Gob Based on Numerical Simulation

2016 ◽  
Vol 9 (1) ◽  
pp. 47-54
Author(s):  
Jing Shen ◽  
Mingran Chang
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Heat Dissipation ◽  
Spontaneous Combustion ◽  
Oxidation Zone ◽  
Effect Analysis ◽  
Mine Fire ◽  
Nitrogen Injection ◽  
The Difference ◽  
Residual Coal

One of the main reasons for coal mine fire is spontaneous combustion of residual coal in gob. As the difference of compaction degree of coal and rock, the underground gob can be considered as a porous medium and divided into “three zones” in accordance with the criteria. The “three zones” are “heat dissipation zone”, “oxidation zone” and “choking zone”, respectively. Temperature programming experiments are taken and numerical simulation with obtained experimental data is utilized to analyze the distribution of “three zones” in this paper. Different width and depth of “oxidation zone” are obtained when the inlet air velocity is changed. As the nitrogen injection has inhibition effect on spontaneous combustion of residual coal in gob, nitrogen is injected into the gob. The widths of “oxidation zone” are compared before and after nitrogen injection. And ultimately the optimum location and volume of nitrogen injection are found out.

scholarly journals Directional Hydraulic Fracturing (DHF) of the Roof, as an Element of Rock Burst Prevention in the Light of Underground Observations and Numerical Modelling

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 562
Author(s):  
Marek Jendryś ◽  
Andrzej Hadam ◽  
Mateusz Ćwiękała
Keyword(s):  
Rock Mass ◽  
Hydraulic Fracturing ◽  
Coal Mining ◽  
Rock Burst ◽  
Coal Mine ◽  
Seismic Activity ◽  
Black Coal ◽  
Directional Hydraulic Fracturing ◽  
Before And After ◽  
The Face

The following article analyzes the effectiveness of directional hydraulic fracturing (DHF) as a method of rock burst prevention, used in black coal mining with a longwall system. In order to define changes in seismic activity due to DHF at the “Rydułtowy” Black Coal Mine (Upper Silesia, Poland), observations were made regarding the seismic activity of the rock mass during coal mining with a longwall system using roof layers collapse. The seismic activity was recorded in the area of the longwall itself, where, on a part of the runway, the rock mass was expanded before the face of the wall by interrupting the continuity of the rock layers using DHF. The following article presents measurements in the form of the number and the shock energy in the area of the observed longwall, which took place before and after the use of DHF. The second part of the article unveils the results of numerical modeling using the discrete element method, allowing to track the formation of goafs for the variant that does not take DHF into consideration, as well as with modeled fractures tracing DHF carried out in accordance with the technology used at “Rydułtowy” coal mine.

scholarly journals Influence of technical parameters on the structure of annular axis braided preforms

2021 ◽  
Vol 28 (1) ◽  
pp. 160-168
Author(s):  
Xi Wang ◽  
Guoli Zhang ◽  
Xiaoping Shi ◽  
Ce Zhang
Keyword(s):  
Cross Section ◽  
Rotation Speed ◽  
Technical Parameters ◽  
Braiding Angle ◽  
Shaped Cross Section

Abstract A modified vertical braiding machine and closed annular axis mandrels with a special-shaped cross section were used to braid annular axis preforms under four different technical parameters. After measuring the braiding angles and yarn spacing of the braided preform in different areas of the mandrels, it was found that the braiding angle increased by 20.9% and the yarn spacing decreased by 19.8% when the speed of the yarn carrier was doubled. The braiding angle decreased by 31.1% and the yarn spacing increased by 28.6% when the rotation speed of the mandrels was doubled. The results show that the rotation speed of the mandrel has a slightly greater influence on the braiding angle and the yarn spacing. By using the modified braiding machine to braid the annular axis preforms, multi-layer continuous braided preforms can be achieved on compact equipment. And the structure of the annular axis braided preforms can be changed by changing the technical parameters.

Reasonable Entry Layout of Lower Seam in Multi-Seam Mining Based on Numerical Simulation

2013 ◽  
Vol 295-298 ◽  
pp. 2980-2984
Author(s):  
Xiang Qian Wang ◽  
Da Fa Yin ◽  
Zhao Ning Gao ◽  
Qi Feng Zhao
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Coal Seam ◽  
Coal Mine ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Geological Conditions ◽  
Seam Mining

Based on the geological conditions of 6# coal seam and 8# coal seam in Xieqiao Coal Mine, to determine reasonable entry layout of lower seam in multi-seam mining, alternate internal entry layout, alternate exterior entry layout and overlapping entry layout were put forward and simulated by FLAC3D. Then stress distribution and displacement characteristics of surrounding rock were analyzed in the three ways of entry layout, leading to the conclusion that alternate internal entry layout is a better choice for multi-seam mining, for which makes the entry located in stress reduce zone and reduces the influence of abutment pressure of upper coal seam mining to a certain extent,. And the mining practice of Xieqiao Coal Mine tested the results, which will offer a beneficial reference for entry layout with similar geological conditions in multi-seam mining.

Numerical Simulation of the Effects of Preheating on Electron Beam Additive Manufactured Ti-6Al-4V Build Plate

2016 ◽  
Vol 879 ◽  
pp. 274-278 ◽  
Author(s):  
Jun Cao ◽  
Philip Nash
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Finite Element ◽  
Electron Beam ◽  
Cross Section ◽  
Element Model ◽  
Normal Direction ◽  
Thermal Residual Stresses ◽  
Longitudinal Residual Stress ◽  
Middle Cross Section

In an earlier study, a 3-D thermomechanical coupled finite element model was built and experimentally validated to investigate the evolution of the thermal residual stresses and distortions in electron beam additive manufactured Ti-6Al-4V build plates. In this study, an investigation using this robust and accurate model was focused on an efficient preheating method, in which the electron beam quickly scanned across the substrate to preheat the build plate prior to the deposition. Various preheat times, beam powers, scan rates, scanning paths and cooling times (between the end of current preheat scan/deposition layer and the beginning of the next preheat scan/deposition layer) were examined, and the maximum distortion along the centerline of the substrate and the maximum longitudinal residual stress along the normal direction on the middle cross-section of the build plate were quantitatively compared. The results show that increasing preheat times and beam powers could effectively reduce both distortion and residual stress for multiple layers/passes components.

Optimal Solutions for Nonhomogeneous Multiply-Connected Torsional Sections

1989 ◽  
Vol 111 (1) ◽  
pp. 87-93 ◽  
Author(s):  
A. Mioduchowski ◽  
M. G. Faulkner ◽  
B. Kim
Keyword(s):  
Numerical Simulation ◽  
Boundary Value Problem ◽  
Cross Section ◽  
Boundary Value ◽  
Optimization Procedure ◽  
Second Order ◽  
External Boundary ◽  
Optimal Solutions ◽  
Torsion Problem ◽  
Multiply Connected

Optimization of a second-order multiply-connected inhomogeneous boundary-value problem was considered in terms of elastic torsion. External boundary and material proportions are the applied constraints in finding optimal internal configurations of the cross section. The optimization procedure is based on the numerical simulation of the membrane analogy and the results obtained indicate that the procedure is usable as an engineering tool. Optimal solutions are obtained for some representative cases of the torsion problem and they are presented in the form of tables and figures.

Sign in / Sign up

Export Citation Format

Share Document