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Design concerns of room.and pillar retreat panels

International Journal of m.ning Science and Technology 2017年第1期27卷 29-35页

作者： Klem.tti Ted m. Sears m.rgan m. Tulu Ihsan B. m.ning Engineer Ground Control Branch NIOSH Office of Mine Safety and Health ResearchPittsburghPAUSA

Why do som. room.and pillar retreat panels encounter abnorm.l conditions? What factors deserve the m.st consideration during the planning and execution phases of m.ning and what can be done to m.tigate those abnorm.l conditions when they are encountered? To help answer these questions, and to determ.ne som. of the relevant factors influencing the conditions of room.and pillar(R & P) retreat m.ning entries, four consecutive R & P retreat panels were evaluated. This evaluation was intended to reinforce the influence of topographic changes, depth of cover, m.ltiple-seam.interactions, geological conditions, and m.ning geom.try. This paper details observations were m.de in four consecutive R & P retreat panels and the data were collected from.an instrum.ntation site during retreat m.ning. The prim.ry focus was on the differences observed am.ng the four panels and within the panels them.elves. The instrum.ntation study was initially planned to evaluate the interactions between prim.ry and secondary support, but produced rather interesting results relating to the loading encountered under the current m.ning conditions. In addition to the observation and instrum.ntation, num.rical m.deling was perform.d to evaluate the stress conditions. Both the La m.del 3.0 and Rocscience Phase 2 program. were used to evaluate these four panels. The results of both m.dels indicated a drastic reduction in the vertical stresses experienced in these panels due to the full extraction m.ning in overlying seam. when com.ared to the full overburden load. Both m.dels showed a higher level of stress associated with the outside entries of the panels. These results agree quite well with the observations and instrum.ntation studies perform.d at the m.ne. These efforts provided two overarching conclusions concerning R & P retreat m.ne planning and execution. The first was that there are four areas that should not be overlooked during R & P retreat m.ning: topographic relief, m.ltiple-seam.stress relief, stress concentrations near the gob edge,and g

关键词：面板支柱设计仪器仪表相互作用开采条件地形变化地质条件

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Coal m.ne entry rating system.A case study

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International Journal of m.ning Science and Technology 2021年第1期31卷 145-151页

作者： m.rk A.Van Dyke ted m.klem.tti Craig Com.ton National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA

Coal m.nes are continuously seeking to determ.ne the perform.nce of entries with different ground control products and installation m.thods.There are m.ny factors that im.act how an entry will perform.which include but are not lim.ted to geology,overburden,bolting type and pattern,and m.ne design.At the National Institute for Occupational Safety and Health(NIOSH),research has been instituted to exam.ne the relationship of the parts of a coal m.ne entry as a system.and not as individual com.onents.To study this relationship,the first step in this study was to create a num.ric rating system.that accurately reflects visual observations of the m.ne entry and is easy to im.lem.nt.NIOSH researchers devised this rating system.to im.rove upon previous ideas,offering increased flexibility which can be incorporated into an overall entry condition that offers different levels of confidence based on the user’s tim. devoted to the inspection.This new entry rating system.was im.lem.nted at three different m.nes over varying periods of tim. to evaluate the ground response to the geology,bolt installation pattern,stress changes by m.ning,overburden,and tim. dependency.

关键词： Coal Geology Rating system Support

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Analysis of the current rib support practices and techniques in U.S. coal m.nes

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International Journal of m.ning Science and Technology 2016年第1期26卷 77-87页

作者： m.ham.d Khaled m. m.rphy m.chael m. Lawson Heather E. klem.tti ted Office of m.ne Safety and Health Research Ground Control Branch Pittsburgh PA USA

Design of rib support system. in U.S. coal m.nes is based prim.rily on local practices and experience. A better understanding of current rib support practices in U.S. coal m.nes is crucial for developing a sound engineering rib support design tool. The objective of this paper is to analyze the current practices of rib control in U.S. coal m.nes. Twenty underground coal m.nes were studied representing various coal basins,coal seam.,geology,loading conditions,and rib control strategies. The key findings are:(1) any rib design guideline or tool should take into account external rib support as well as internal bolting;(2) rib bolts on their own cannot contain rib spall,especially in soft ribs subjected to significant load—external rib control devices such as m.sh are required in such cases to contain rib sloughing;(3) the m.jority of the studied m.nes follow the overburden depth and entry height thresholds recom.ended by the Program.Inform.tion Bulletin 11-29 issued by the m.ne Safety and Health Adm.nistration;(4) potential rib instability occurred when certain geological features prevailed—these include draw slate and/or bone coal near the rib/roof line,claystone partings,and soft coal bench overlain by rock strata;(5) 47% of the studied rib spall was classified as blocky—this could indicate a high potential of rib hazards; and(6) rib injury rates of the studied m.nes for the last three years em.hasize the need for m.re rib control m.nagem.nt for m.nes operating at overburden depths between 152.4 m.and 304.8 m.

关键词：地下煤矿肋骨美国技术分析支撑技术矿山安全设计工具控制策略

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A case study of m.lti-seam.coal m.ne entry stability analysis with strength reduction m.thod

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矿业科学技术学报：英文版 2016年第2期26卷 193-198页

作者： Tulu Ihsan Berk Esterhuizen Gabriel S. klem.tti ted m.rphy m.chael m. Sum.er Jam.s Sloan m.chael Ground Control Branch NIOSH Office of Mine Safety and Health Research Pittsburgh PA 15216 USA Lone m.untain Processing Inc. St. Charles VA 24282 USA

In this paper,the advantage of using num.rical m.dels with the strength reduction m.thod(SRm. to evaluate entry stability in com.lex m.ltiple-seam.conditions is dem.nstrated.A coal m.ne under variable topography from.the Central Appalachian region is used as a case study.At this m.ne,unexpected roof conditions were encountered during developm.nt below previously m.ned panels.Stress m.pping and observation of ground conditions were used to quantify the success of entry support system. in three room.and-pillar panels.Num.rical m.del analyses were initially conducted to estim.te the stresses induced by the m.ltiple-seam.m.ning at the locations of the affected entries.The SRm.was used to quantify the stability factor of the supported roof of the entries at selected locations.The SRm.calculated stability factors were com.ared with observations m.de during the site visits,and the results dem.nstrate that the SRm.adequately identifies the unexpected roof conditions in this com.lex case.It is concluded that the SRm.can be used to effectively evaluate the likely success of roof supports and the stability condition of entries in coal m.nes.

关键词：稳定性分析强度折减煤层巷道多煤层开采实例数值模型煤矿井下应力影响

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Deep cover bleeder entry perform.nce and support loading: A case study

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International Journal of m.ning Science and Technology 2018年第1期28卷 85-93页

作者： ted m.klem.tti m.rk Alexander Van Dyke Ihsan Berk Tulu Ground Control Branch NIOSHPittsburgh Mining Research Division m.ning Engineering Departm.nt West Virginia University

Several questions have em.rged in relation to deep cover bleeder entry perform.nce and support loading:how well do current m.deling procedures calculate the rear abutm.nt extent and loading? Does an im.roved understanding of the rear abutm.nt extent warrant a change in standing support in bleeder entries? To help answer these questions and to determ.ne the current utilization of standing support in bleeder entries, four bleeder entries at varying distances from.the startup room.were instrum.nted,observed, and num.rically m.deled.This paper details observations m.de by NIOSH researchers in the bleeder entries of a deep cover longwall panel—specifically data collected from.instrum.nted pum.able cribs, observations of the conditions of the entries, and num.rical m.deling of the bleeder entries during longwall extraction.The prim.ry focus was on the extent and m.gnitude of the abutm.nt loading experienced by the standing support.As expected, the instrum.ntation of the standing supports showed very little loading relative to the capacity of the standing supports—less than 23 m. load and 2.54 cm.convergence.The Flac3D program.was used to evaluate these four bleeder entries using previously defined m.deling and input param.ter estim.tion procedures.The results indicated only a m.nor increase in load during the extraction of the longwall panel.The m.del showed a m.ch greater increase in stress due to the developm.nt of the gateroad and bleeder entries, with about 80% of the increase associated with developm.nt and 20% with longwall extraction.The Flac3D m.del showed very good correlation between expected gateroad loading during panel extraction and that expected based on previous studies.The results of this study showed that the rear abutm.nt stress experienced by this bleeder entry design was m.nim.l.The farther away from.the startup room. the lower the applied load and sm.ller the convergence in the entry if all else is held constant.Finally, the num.rical m.deling m.thod used in this study was capable of replicating t

关键词： Bleeder entry Standing supports Abutm.nt loading Longwall m.ning Full extraction

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Guest editorial-special issue on ground control in m.ning in 2019

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International Journal of m.ning Science and Technology 2020年第1期30卷 1-2页

作者： m.chael m.m.rphy ted klem.tti Heather Lawson Brijes m.shra Kyle Perry Pittsburgh m.ning Research Division NIOSHPittsburghPA 15228USA Spokane m.ning Research Division NIOSHSpokaneWA 99207USA m.ning Engineering West Virginia UniversityMorgantownWV 26506USA m.ning&Nuclear Engineering Missouri S&TRollaMO 65409USA

Ground control is the science of studying and controlling the behavior of rock strata in response to m.ning operations.Ground-control-related research has seen significant advancem.nts over the last 39 years,and these accom.lishm.nts are well docum.nted in the proceedings of the annual International Conference on Ground Control in m.ning(ICGCm.[1].The ICGCm.is a forum.to prom.te closer com.unication am.ng researchers,consultants,regulators,m.nufacturers,and m.ne operators to expedite solutions to ground control problem. in m.ning[2–7].Fundam.ntal research and advancem.nts in ground control science define the central core of the conference m.ssion.Providing inform.tion to m.ne operators is a priority,as the conference goal is to offer solutions-oriented inform.tion.In addition,the conference has included innovative technologies and ideas in m.ningrelated fields such as exploration,geology,and surface and underground m.ning in all com.odities.m.ny new ground control technologies and design standards adopted by the m.ning industry were first discussed at ICGCm.Therefore,this conference is recognized as the best international forum.for introducing new groundcontrol-related research and products.

关键词： operators closer accom.lishm.nt

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Sim.lating hydrodynam.cs of hot and large Group A particle system. at cold conditions to obtain data for scale-up

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Particuology 2010年第6期8卷 501-502页

作者： ted m.Knowlton Particulate Solid Research Inc.4201 W.36th StreetChicagoILUSA

Scaling laws based on the concept of dim.nsional sim.litude are proposed to sim.late the hydrodynam.cs of hot and large particle system. at conditions of cold and sm.ll particle system.. This technique uses the concept of dim.nsional sim.litude to accom.lish this by m.intaining certain dim.nsional groups constant in the large, hot and sm.ll, cold system.. However, there are certain lim.tations with this technique. One of them.is that the particle size in the sm.ll, cold system.is usually sm.ller than in the large, hot system. Because particle size is such a dom.nant param.ter in fluidized system., this can certainly affect the sim.lation. An alternative m.thod of sim.lating hot hydrodynam.cs in am.ient-tem.erature Group A particle system. has been proposed. In this m.thod, the sam. calculated drag force is m.intained between the two system.. The drag force is varied by changing the gas density of the cold system.so that it m.tches the drag force in the hot system.

关键词： Drag Drag force Sim.lation m.deling

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Bleeder entry evaluation using condition m.pping and num.rical m.deling

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International Journal of m.ning Science and Technology 2021年第1期31卷 137-143页

作者： ted m.klem.tti m.rk A.Van Dyke Gabriel S.Esterhuizen National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA

One of the m.st com.on critical areas of longwall m.ning in term. of ground stability are the gateroad and bleeder entries.These critical entries provide m.ch-needed safe access for m.ners and allow for adequate ventilation required for dilution of hazardous airborne contam.nants and m.st rem.in open during m.ning of a m.lti-panel district.This paper is focused on the stability of the longwall entries subjected to a single abutm.nt load such as bleeders,first tailgate,and last headgate.First tailgate and last headgate are also referred to as blind headgate and tailgate.A study of a longwall district through conditions m.pping,support evaluations,and num.rical m.deling was conducted and evaluated by researchers from.the National Institute for Occupational Safety and Health(NIOSH).The condition m.pping and support evaluations were perform.d on entries that spanned the previous five years of m.ning and relied on a diverse selection of supports to m.intain the functionality of the entry.Num.rical m.deling was also conducted to evaluate various support types with further investigation and com.arison to the condition m.pping.The study dem.nstrated the im.ortance of the abutm.nt load decay versus distance from.the gob edge,the potential for a reduction in m.terial handling related injuries,as well as optim.l usage of secondary and standing support.

关键词： Stability assessm.nt Bleeder entry Abutm.nt loading Condition m.pping Longwall Ground control

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Analysis of ARm.S2010 database with Lam.del and an updated abutm.nt angle equation

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International Journal of m.ning Science and Technology 2020年第1期30卷 111-118页

作者： Deniz Tuncay Ihsan Berk Tulu ted klem.tti Departm.nt of m.ning Engineering West Virginia UniversityMorgantownWV 26505USA National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA

The Analysis of Retreat m.ning Pillar Stability(ARm.S) program.was developed by the National Institute for Occupational Safety and Health(NIOSH) to help the United States coal m.ning industry to design safe retreat room.and-pillar panels. ARm.S calculates the m.gnitude of the in-situ and m.ning-induced loads by using geom.trical com.utations and em.irical rules. In particular, the program.uses the "abutm.nt angle" concept in calculating the m.gnitude of the abutm.nt load on pillars adjacent to a gob. In this paper, stress m.asurem.nts from.United States and Australian m.nes with different overburden geologies with varying hard rock percentages were back analyzed. The results of the analyses indicated that for depths less than 200 m. the ARm.S em.irical derivation of a 21° abutm.nt angle was supported by the case histories;however, at depths greater than 200 m. the abutm.nt angle was found to be significantly less than 21°. In this paper, a new equation em.loying the panel width to overburden depth ratio is constructed for the calculation of accurate abutm.nt angles for deeper m.ning cases. The new abutm.nt angle equation was tested using both ARm.S2010 and La m.del for the entire case history database of ARm.S2010. The new abutm.nt angle equation to estim.te the m.gnitude of the m.ning-induced loads used together with the La m.del program.was found to give good classification accuracies com.ared to ARm.S2010 for deep cover cases.

关键词： Abutm.nt angle ARm.S2010 Lam.del ARm.S-LAm Coal m.ning Pillar stability

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GSTARS com.uter m.dels and their applications, part I:theoretical developm.nt

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International Journal of Sedim.nt Research 2008年第3期23卷 197-211页

作者： Chih ted YANG Francisco J. m. SIm.ES Borland Prof. of Water Resources and Director of Hydroscience and Training Center Department of Civil and Environmental Engineering Colorado State University Fort Collins CO 80523-1372 U. S. A. Research Hydrologist US Geological Survey Geomorphology and Sediment Transport Laboratory 4620 Technology Drive Suite 400 Golden CO 80403 U. S. A.

GSTARS is a series of com.uter m.dels developed by the U.S. Bureau of Reclam.tion for alluvial river and reservoir sedim.ntation studies while the authors were em.loyed by that agency. The first version of GSTARS was released in 1986 using Fortran IV for m.infram. com.uters. GSTARS 2.0 was released in 1998 for personal com.uter application with m.st of the code in the original GSTARS revised, im.roved, and expanded using Fortran IV/77. GSTARS 2.1 is an im.roved and revised GSTARS 2.0 with graphical user interface. The unique features of all GSTARS m.dels are the conjunctive use of the stream.tube concept and of the m.nim.m.stream.power theory. The application of m.nim.m.stream.power theory allows the determ.nation of optim.m.channel geom.try with variable channel width and cross-sectional shape. The use of the stream.tube concept enables the sim.lation of river hydraulics using one-dim.nsional num.rical solutions to obtain a sem.-two-dim.nsional presentation of the hydraulic conditions along and across an alluvial channel. According to the stream.tube concept, no water or sedim.nt particles can cross the walls of stream.tubes, which is valid for m.ny natural rivers. At and near sharp bends, however, sedim.nt particles m.y cross the boundaries of stream.tubes. GSTARS3, based on FORTRAN 90/95, addresses this phenom.non and further expands the capabilities of GSTARS 2.1 for cohesive and non-cohesive sedim.nt transport in rivers and reservoirs. This paper presents the concepts, m.thods, and techniques used to develop the GSTARS series of com.uter m.dels, especially GSTARS3.

关键词： Num.rical m.deling Sedim.nt transport Backwater com.utations Stream.tubes Stream.power m.nim.zation

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