Large Section Open-Off Cut Supporting Technology of Fully Mechanized Caving Mining for Carboniferous Extra-Thick Coal Seam

2013 ◽  
Vol 734-737 ◽  
pp. 566-569 ◽  
Author(s):  
Qing Guo Huang ◽  
Feng Gao
Keyword(s):  
Steel Strip ◽  
High Strength ◽  
Wall Rock ◽  
Metal Mesh ◽  
Large Section ◽  
Tunnel Wall ◽  
Thick Coal Seam ◽  
Working Face ◽  
Strip Metal ◽  
High Possibility

In order to resolve the supporting problems of the open-off cuts with span of 10m in Tashan coal mine No.3~5 coal seams, this study investigated and analyzed the problems in the current open-off cuts supporting and the supporting parameters, and performed laboratory test and analysis to the coal and rock's mechanical properties. The open-off cut wall rock in Tashan mine has the problem of serious deformation and high possibility of sudden falling. After academic analysis and numerical calculation, a new supporting mode is designed for the supporting of large span open-off cuts: unite high strength anchor bar, combined anchor rope, W steel strip, metal mesh and concrete to form a group anchor seal effect, therefore maintain the tunnel wall rock's stability and safety. Engineering test was conducted at the 8105 working face open-off cuts, the anchor rope's anchorage force changes in the range of 140 ~ 160kN, the maximum delaminating value of the roof in anchorage zone is about 7mm, and the maximum roof-to-floor convergence is 38mm. The result shows that the proposed "anchor bar - combined anchor rope - concrete" supporting model improved the overall bearing capacity of the supporting structure, controlled the tunnel wall rock's deformation effectively, and also achieved the desired effect of the supporting design, ensured the safety of the large section open-off cuts.

The Application of New High-Strength Polyester Fiber Flexible Net for the End Coal Mining Through

2013 ◽  
Vol 750-752 ◽  
pp. 2141-2144
Author(s):  
Qi Tao Duan ◽  
Guo Yin Shang ◽  
Zhu He Xu ◽  
Xi Wen Zhang
Keyword(s):  
High Efficiency ◽  
Low Cost ◽  
Cutting Speed ◽  
High Strength ◽  
Mining Area ◽  
Polyester Fiber ◽  
Construction Technology ◽  
Metal Mesh ◽  
Working Face ◽  
Mesh Material

Shendong mining area hanging nets adopted metal mesh material in the traditional through of fully mechanized coal face. Whose defects were the high cost of materials, process cumbersome, great labor intensity and time consuming. Therefore, new high-strength polyester fiber flexible mesh material was introduced. Its main advantages are: light weight, tensile resistance and drag force strong, flame-retardant and anti-static, low cost, simple process, high efficiency, coal cutting speed. The construction technology process in detail were designed which contained flexible network transported, fixed, dropped and raised. The project was implemented in Shigetai Coal at the end of No.12401 mining face. Results show that from working face mounting network to smoothly through with only 40 hours, compared with the traditional metal net can save 44 hours and cost 480000 yuan.

scholarly journals Reasonable Arrangement of High-Level Orientation Extraction Boreholes of Pressure Relief Gas in Overlying Strata under High-Strength Fully Mechanized Mining in Low-Gas-Thick-Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Han Gao ◽  
Xuanping Gong ◽  
Xiaoyu Cheng ◽  
Rui Yu ◽  
Hui Wang
Keyword(s):  
Coal Seam ◽  
Gas Flow ◽  
High Strength ◽  
Distribution Characteristics ◽  
Pressure Relief ◽  
Gas Field ◽  
Thick Coal Seam ◽  
Gas Accumulation ◽  
Working Face ◽  
Gas Control

In order to solve the problem of pressure relief gas control under high-strength fully mechanized top-coal caving in low-gas-thick-coal seams, this paper studies the evolution of overburden structures and the distribution characteristics of fissure fields during the initial and stable period of working face by physical simulation and numerical analysis. The mathematical model of coupling between mining fracture field and pressure relief gas field is established. The results reveal the distribution characteristics of pressure relief gas field that considers mining-induced fissure field. According to the distribution of mining gas accumulation area, the high directional long boreholes have been put forward to control the pressure relief gas in goafs, and the effect has been tested. The results show that the initial pressure and three periodic pressures occurred from the cutting hole to 135 m in the initial mining period of the working face. The height of collapse zone developed to 22 m, and fracture height developed to 75 m. The development height of caving zone is stable at 25∼27 m, and the development height of fissure zone is stable at 75∼95 m. The process and distribution of pressure relief gas flow in goaf are obtained by solving the numerical model of pressure relief gas flow in mining fissure field. The gas accumulation area is located within 25∼55 m from return laneway and 25∼50 m from the roof of coal seam. After the implementation of high directional long drilling gas drainage technology in the initial mining period and the stable mining period, good results have been obtained in the gas control, where the average concentration of gas extraction is 5.8%, the average gas flow rate is 0.71 m3/min, and the gas concentration in upper corner and return air is less than 0.8%. The results can provide a reference for pressure relief gas control under similar conditions.

scholarly journals Study on Fracture and Stress Evolution Characteristics of Ultra-Thick Hard Sandstone Roof in the Fully Mechanized Mining Face with Large Mining Height: A Case Study of Xiaojihan Coal Mine in Western China

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Feng Ju ◽  
Meng Xiao ◽  
Zequan He ◽  
Pai Ning ◽  
Peng Huang
Keyword(s):  
High Strength ◽  
Western China ◽  
Stress Evolution ◽  
Working Face ◽  
Mining Condition ◽  
Evolution Characteristics ◽  
Large Mining Height ◽  
Evolution Laws ◽  
Mining Face ◽  
Mining Height

Ultra-thick hard sandstone roofs present high thickness, poor delamination, and wide caving range. The strata pressure of the working face during actual mining increases, having a significant influence on the safe mining of the working face. Especially, in the mining areas of western China, the fully mechanized mining faces with high mining height and high-strength mining are more prominent. Understanding the fractures and stress evolution characteristics of the ultra-thick hard sandstone roof during actual mining is of high significance to control the dynamic pressure on the working face. In this paper, the typical ultra-thick hard sandstone roof of the Xiaojihan coal mine was taken as an example. The structural and chemical composition characteristics were analyzed. Besides, the fracture characteristics of ultra-thick hard roof during the working face mining were analyzed. Moreover, the fracture structure consistency was verified through physical simulation and a field measurement method. Finally, the stress evolution laws in the ultra-thick hard sandstone roof fracture were studied through numerical simulation. The findings demonstrated that (1) the ultra-thick hard sandstone roof was composed of inlaid coarse minerals, which had compact structure, while the Protodyakonov hardness reached up to 3.07; (2) under the high-strength mining condition of fully mechanized mining face with large mining height, the ultra-thick hard sandstone roof had the characteristics of brittle fracture, with a caving span of 12 m; (3) under the high-strength mining condition of fully mechanized mining face with large mining height, the ultra-thick hard sandstone roof followed the stress evolution laws that were more sensitive to the neighboring goaf. Therefore, it was necessary to reduce the fracture span or layering of ultra-thick hard sandstone roof through the manual intervention method adoption or increase either the strength of coal pillar or supporting body, to resist the impact generated during ultra-thick hard sandstone roof fracture.

scholarly journals A numerical simulation of realistic top coal caving intervals under different top coal thicknesses in longwall top coal caving working face

2021 ◽  
Author(s):  
Chuang Liu ◽  
Huamin Li
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Distinct Element ◽  
Simulation Models ◽  
Simulation Software ◽  
Thick Coal Seam ◽  
Coal Recovery ◽  
Working Face ◽  
Longwall Top Coal Caving ◽  
Selection Of

Abstract In the process of longwall top coal caving, the selection of the top coal caving interval along the advancing direction of the working face has an important effect on the top coal recovery. To explore a realistic top coal caving interval of the longwall top coal caving working face, longwall top coal caving panel 8202 in the Tongxin Coal Mine is used as an example, and 30 numerical simulation models are established by using Continuum-based Distinct Element Method (CDEM) simulation software to study the top coal recovery with 4.0 m, 8.0 m, 12.0 m, 16.0 m, 20.0 m and 24.0 m top coal thicknesses and 0.8 m, 1.0 m, 1.2 m, 1.6 m and 2.4 m top coal caving intervals. The results show that with an increase in the top coal caving interval, the single top coal caving amount increases. The top coal recovery is the highest with a 0.8 m top coal caving interval when the thickness of the top coal is less than 4.0 m, and it is the highest with a 1.2 m top coal caving interval when the coal seam thickness is greater than 4.0 m. These results provide a reference for the selection of a realistic top coal caving interval in thick coal seam caving mining.

In-Field Application of Steel Strip Reinforcement for Pipeline External Rehabilitation

2010 ◽  
Author(s):  
Nicholas J. Venero ◽  
Tim J. M. Bond ◽  
Raymond N. Burke ◽  
David J. Miles
Keyword(s):  
Steel Strip ◽  
New Technology ◽  
High Strength ◽  
Field Application ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Precise Control ◽  
Ultra High Strength Steel ◽  
Structural Adhesive ◽  
Pipeline Design

A new technology for external rehabilitation of pipelines, known as XHab™, has been developed. This method involves wrapping multiple layers of ultra-high strength steel (UHSS) strip in a helical form continuously over an extended length of pipeline using a dedicated forming and wrapping machine. The reinforcement afforded by the strip can be used to bring a defective section of pipe (e.g. externally corroded or dented) back to its original allowable operating conditions, or even to increase the allowable operating pressure if the desired operating conditions exceed the original pipeline design limits. This paper describes the design, manufacture and testing process for a self-propelled wrapping machine for in-field rehabilitation. The wrapping apparatus consists of several major components including an opening sufficiently wide to receive the pipe, a movement assembly, a winding head, a preforming device, an accumulator and an oscillating adhesive applicator. The wrapping apparatus uses the winding head to wrap the reinforcing steel strip around the pipe. The movement assembly uses a pair of tracks in contact with the pipe to drive the wrapping apparatus along which enables helical wrapping of the reinforcing strip material. The oscillating adhesive assembly applies structural adhesive to the pipe immediately before the strip is wound. The winding head, motive assembly and adhesive applicator are electronically synchronized to one another to enable precise control of pitch and adhesive volume. The paper also describes the field application of XHab including mobilization/demobilization of equipment and interaction with other rehabilitation equipment, as well as specific aspects such as initiation and termination of wrapping, protection of rehabilitated area and implementation of cathodic protection.

scholarly journals Gas Distribution Law for the Fully Mechanized Top-Coal Caving Face in a Gassy Extra-Thick Coal Seam

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Wenlin Wang ◽  
Fangtian Wang ◽  
Bin Zhao ◽  
Gang Li
Keyword(s):  
Longwall Mining ◽  
Volume Fraction ◽  
Vertical Direction ◽  
Thick Coal Seam ◽  
Working Face ◽  
Coal Wall ◽  
The Face ◽  
Fraction Distribution ◽  
Gas Volume Fraction ◽  
Gas Volume

Mine gas overflow is a serious threat to the safe and efficient longwall mining of gassy coal seams. Based on the field mining conditions and gas extraction of the fully mechanized top-coal caving face of a gassy coal mine, the space volume fraction distribution and emission (extraction rate) of gas in the face were tested by an arrangement of measuring points in the stereo grid. The isograms of gas volume fraction distribution for each measurement section and air direction in the face are drawn. The research shows that each measurement section gas volume fraction distribution is presented for an asymmetric concave curve along the vertical direction of the coal wall in the air-inlet side and the air-return side of the face; on the working face air-return side, the determination of gas volume fraction distribution of the section appears as falling straight line along the vertical direction of the coal wall. Before the first weighting, the absolute quantity of gas emission in the working face increased with the advancing of the working face, reached the maximum at the time of the first weighting, and then remained stable.

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