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WORKOUTImmediate roof material in a certain coal mine comprises of a sandstone layer 40cm thick and isoverlain by 1.5m of another rock type more stronper/competent than the sand stone. Sandstone hastensile strength of 5Mpa and density of 2.5tm3.
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This study explores the discharge and ignition characteristics of roof indentation fracture to identify the real ignition source of a gas explosion in a coal mine goaf. Theoretical and experimental analyses conclude that the charge of the coal mine roof sandstone will gradually escape from the surface during the loading process.
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Furthermore, for coal samples from Shengli (SL) Coal Mine and Yuanbaoshan (YB) Coal Mine, the initial heat release temperature and the end temperature both conform to the Lorentz function T = T 0 + 2 A (B 4 (M − M c) 2 + B 2). Thermodynamic parameters reach the maximum under the moisture content of 12%–17% where the …
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largely determines the thickness of the mine roof structure. All coal mine roof in the United States must be bolted, and the bolts bind the different layers together. Generally, the layers above the bolts have much less influ-ence than the units that are penetrated by the roof bolts. Moreover, experience in many U.S. coalfields has
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Experimental study on mechanical-electrical ignition characteristics of roof sandstone in a coal mine ZHENHAI HOU1,2, DEMING WANG1,2,*, YANAN WANG1,2, WEI ZHANG1,2, SHUN WU1,2, SHENGYUN LUO3 and YUNFEI ZHU4 1Key Laboratory of Gas and Fire Control for Coal Mines (China University of Mining and Technology), Ministry of …
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The thick-bedded sandstone roof of the Bayangaole coal mine is at risk of rock burst accidents. Hydraulic fracturing technology has been used to prevent these accidents by controlling coal seam roof collapse. To research the crack propagation mechanism of hydraulic fracturing in thick-bedded sandstone roof, hydraulic fracturing …
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The coal seam roof sandstone (CSRS) specimens were taken from Shenhua Heidaigou open pit coal mine located in Inner Mongolia province, China. The sandstone …
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Roof and rib conditions vary from mine to mine (and in some instances from section to section within a mine). The type of sedimentary rock (such as shale, sandstone, and …
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sandstone may also reduce roof strength by increasing the shale's moisture content. In addition, since sandstones are generally much stiffer than shale, they may concentrate …
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1. Immediate roof material in a certain coal mine comprises of a sandstone layer 40cm thick and is overlain by 1.5m of another rock type more stronger/competent than the sand stone. Sandstone has tensile strength of 6Mpa and density of 2.5t/m3. Advise the mine manager on the maximum cut-out distance based on the factor of safety of 1.2.
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Figure 1.–Injuries caused by the fall of roof and rib in U.S. coal mines, 1983-99. Figure 2.–Fatalities caused by the fall of roof and rib in U.S. coal mines, 1983-99. safety and productivity. These structures weaken the roof beam and can cause damage that is not prevented by conventional roof support. In addition, the occurrence of the
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DOI: 10.1016/J.FUEL.2021.120208 Corpus ID: 233546946; Discharge and ignition characteristics from indentation fracture of coal mine roof @article{Lu2021DischargeAI, title={Discharge and ignition characteristics from indentation fracture of coal mine roof}, author={Yi Lu and Min Li and Deming Wang and Xin-Ying Shi and He Li and Yunfei Zhu …
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and roof fall rate at six U.S. mines [Mark et al. 1994]. Figure 8.—Stress on a typical element of mine roof. The overburden load, on the other hand, is primarily carried by the pillars, but it can affect the immediate roof stability (and thus support loading) byC $ Causing sloughage of the pillars, thereby increasing the roof span in the mine ...
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Fossil trees in mine roofs often have a coal rim and are slickensided, which can be unstable in mine roofs. ... Trends: Fossil trees are most common in gray shale roofs and in stackrock roofs. They are uncommon in sandstone channels and black shale and marine roofs. In some mines, increased frequency of kettlebottoms occurs along …
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To explore the causes of mine tremors in coal mines with sandstone roofs, a three-point bending loading experiment was designed for composite sandstone layers, and the fracture and interlayer shear slip characteristics of the composite sandstone layers were studied using optical measurement and acoustic emission techniques. The …
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Thick-Bedded Sandstone Coal Mine Roof Shankun Zhao 1, 2, 3, Maohong Yao 4, Yingjie Li 3*, Haitao Chai 1, 2, Jianping Zuo 3* 1 Mine Safety Technology Branch, China Coal Research Institute ...
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The coal seam roof sandstone (CSRS) specimens were taken from Shenhua Heidaigou open pit coal mine located in Inner Mongolia province, China. The sandstone blocks containing carbon were processed into standard cylindrical specimens with the diameter of 50 mm and the height of 100 mm.
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The sandstone generates current and voltage, which indicates the existence of charge flow in the coal mine roof sandstone during mining. The property can provide experimental basis for the mechanism of electromagnetic radiation and the …
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repeated loading and unloading. The water-rich sand-stone underwent significant plastic deformation, which greatly influenced permeability. The test aims to understand the evolution of sandstone permeability of the aquifer coal seam roof under plastic flow. Rock specimens were from the roof of Xiaojihan coal mine, with the size of 50 mm 9 ...
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Direct in-mine measurements of horizontal stress in Illinois Basin mines, mostly in roofs above the two study coals, have found a range in magnitudes from 1,207 to 3,191 psi and orientations from ...
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Directional fracturing technology for coal and rock is crucial for preventing accidents resulting from the rupture of the hard roof in coal mines. Supercritical carbon …
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Many roof fall accidents might have been averted if sandstone channel characteristics had been recognized and suitable adjustment in roof control methods had been made. The Mine Safety and Health Administration conducted geologic roof control investigations at coal mines in the Pittsburgh coal seam in western Pennsylvania, the Beckley coal …
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ASSESSING COAL MINE ROOF STABILITY THROUGH ROOF FALL ANALYSIS By Gregory M. Molinda,1 Christopher Mark, Ph.D.,2 and Dennis Dolinar3 ABSTRACT In 1999, 2,087 unplanned roof falls were reported from 841 mines. Nearly 55% of all mines reported at least one roof fall, and nearly 17% of the mines reported five or more falls. …
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The sandstone fissure aquifer of the Permian main mining coal seam is the direct water-filled aquifer of the coal mine in northern Anhui Province, China. Hydro-chemistry is important for solving the issue related to water disasters of coal mines, as it can be used for the determination of source of inrush water, and understanding the …
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The aforementioned system tests the evolution rules of current and voltage generated by the coal mine sandstone roof at different loading rates; the formation mechanism and coupling rules with ...
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NIOSH has investigated roof failure in a number of coal mines in order to illustrate the causes and conditions leading up to a roof fall. Roof fall surveillance data indicate that a …
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The longwall mine considered in this study is in Buchanan County, ia, and mines the Pocahontas No. 3 coal seam. Since the publishing of the first seismic forecasting paper [], the mine has mined in two areas: first was the East panels, followed by the finishing of the remaining areas of the Right panel district (see Fig. 1).The East …
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Sparks produced by the Renlou coal mine roof sandstone in low light. 4. Conclusion. In this study, the electric discharge characteristics during the deformation and fracture of the roof sandstone and the characteristics of the disaster caused by electric spark ignition of the gas were studied. The main conclusions are as follows:
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Variable Roof Rock – Sandstone, Shale, and Coal Interspersed. 4 • Coal has been mined in the United States for more than 200 years. Most of today's ... By recognizing and understanding these issues and conditions that continue to make coal mine roof and ribs so hazardous, we can begin to make progress in finding better ways to prevent ...
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Coal mine roof that falls before the installa tion of roof bolts can be hazardous. From 1995-2008, 24 . ... The mine maps sandstone in the roof and has identified complete coal seam .
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Some sandstone roof falls occur along inclined bedding, such as these examples from the Jellico and Harlan coal beds in eastern Kentucky. Trends: Local falls in sandstone generally occur along bedding weaknesses, which may follow overall bed dip or may be caused by internal scours. Some sandstones are actually composites of different …
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2.1 Experiments 2.1.1 Sample Preparation. Coal and roof sandstone taken from an underground coal mine in Shanxi Province, China, at a depth of about 500 m were utilized. The rock blocks were processed into cylindrical samples with a diameter of 50 mm and a height of 100 mm (as shown in Fig. 1).Three samples were prepared and tested …
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This research is intended to guide Quinsam Coal and other coal mines globally in efforts to develop or optimize coal extraction and address the geomechanical challenges …
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The sandstone samples were collected from the No. 4 coal seam roof of the Panbei Coal Mine in Huainan and Huaibei Mining Area, China. Unweathered …
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A roof of a particular coal mine comprises of interlaminated shale/mudstone bands ( 13, 14,16,20,15 and 19) cms overlain by competent sandstone layer 1m thick.Given that;Hole diameter is 26mmBolt diameter 20mmSteel strength 600MPaRoadwidth 7.0mSandstone UTS 5MPaSandstone density 2650kgm3Take note that a pull test was …
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This paper provides a case study in machine learning using Artificial Neural Network (ANN) and geophysical log data information from an underground coal mine …
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