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| 1 | Ground response to high horizontal stresses during longwall retreat and its implications for longwall headgate support显示文摘Roof falls in longwall headgate can occur when weak roof and high horizontal stress are present. To prevent roof falls in the headgate under high horizontal stress, it is important to understand the ground response to high horizontal stress in the longwall headgate and the requirements for supplemental roof support. In this study, a longwall headgate under high horizontal stress was instrumented to monitor stress change in the pillars, deformations in the roof, and load in the cable bolts. The conditions in the headgate were monitored for about six months as the longwall face passed by the instrumented site.The roof behavior in the headgate near the face was carefully observed during longwall retreat.Numerical modeling was performed to correlate the modeling results with underground observation and instrumentation data and to quantify the effect of high horizontal stress on roof stability in the longwall headgate. This paper discusses roof support requirements in the longwall headgate under high horizontal stress in regard to the pattern of supplemental cable bolts and the critical locations where additional supplemental support is necessary. | Peter Zhang Dave Gearhart Mark Van Dyke Daniel Su Essie Esterhuizen Berk Tulu | 2019 | International Journal of Mining Science and Technology2019，29，1： | 6 |
| 2 | Analysis of gateroad stability at two longwall mines based on field monitoring results and numerical model analysis显示文摘Coal mine longwall gateroads are subject to changing loading conditions induced by the advancing longwall face. The ground response and support requirements are closely related to the magnitude and orientation of the stress changes, as well as the local geology. This paper presents the monitoring results of gateroad response and support performance at two longwall mines at a 180-m and 600-m depth of cover.At the first mine, a three-entry gateroad layout was used. The second mine used a four-entry, yieldabutment-yield gateroad pillar system. Local ground deformation and support response were monitored at both sites. The monitoring period started during the development stage and continued during first panel retreat and up to second panel retreat. The two data sets were used to compare the response of the entries in two very different geotechnical settings and different gateroad layouts. The monitoring results were used to validate numerical models that simulate the loading conditions and entry response for these widely differing conditions. The validated models were used to compare the load path and ground response at the two mines. This paper demonstrates the potential for numerical models to assist mine engineers in optimizing longwall layouts and gateroad support systems. | Gabriel S.Esterhuizen David F.Gearhart Ted Klemetti Heather Dougherty Mark van Dyke | 2019 | International Journal of Mining Science and Technology2019，29，1： | 5 |
| 3 | Transitional geology and its effects on development and longwall mining in Pittsburgh Seam显示文摘This paper presents the geologic and ground control challenges that were encountered by Consol Energy's coal mining operations in southwestern Pennsylvania,USA. Geologic encounters,such as sandstoneto-limestone geology transition,massive sandstone channels,shale channels,pyritic rich green claystone,laminated roof,and soft floor,have significantly impacted the development and longwall mining in Consol's Pittsburgh Seam coal mines. Experience from different mines shows that,in the sandstone-to-limestone geology transition zone,1.83 m high-tension,fully-grouted primary bolts employed along with 4.88 m center cable bolts at every other strap greatly improved beam building and ensured proper anchorage into the competent roof. Hydraulic fracturing of the massive sandstone was often necessary to enhance caving of the massive sandstone behind the shields to relieve pressure at the face. The presence of soft floor coupled with presence of thick floor coal and deep cover,induced excessive headgate convergence during retreat of the first right hand longwall panel. In all,it is important to explore the roof and in-seam geology in detail to delineate normal and anomalous geologic conditions prior to and during development. With diligent geologic reconnaissance,geotechnical monitoring,and assessment,site-specific geotechnical solutions have been provided to mine operations to improve safety and productivity. | Lu Jun Van Dyke Mark Su Daniel W.H. Hasenfus Greg | 2016 | International Journal of Mining Science and Technology2016，26，1： | 3 |
| 4 | Some properties of keratin biomaterials: Kerateines显示文摘 | Paulina Hill Helen Brantley Mark Van Dyke | 2009 | Biomaterials2009，，4： | 1 |
| 5 | Geologic data collection and assessment techniques in coal mining for ground control显示文摘The identification and mitigation of adverse geologic conditions are critical to the safety and productivity of underground coal mining operations.To anticipate and mitigate adverse geologic conditions,a formal method to evaluate geotechnical factors must be established.Each mine is unique and has its own separate approach for defining what an adverse geological condition consists of.The collection of geologic data is a first critical step to creating a geological database to map these hazards efficiently and effectively.Many considerations must be taken into account,such as lithology of immediate roof and floor strata,seam height,gas and oil wells,faults,depressions in the mine floor(water)and increases in floor elevation(gas),overburden,streams and horizontal stress directions,amongst many other factors.Once geologic data is collected,it can be refined and integrated into a database that can be used to develop maps showing the trend,orientation,and extent of the adverse geological conditions.This information,delivered in a timely manner,allows mining personnel to be proactive in mine planning and support implementations,ultimately reducing the impacts of these features.This paper covers geologic exploratory methods,data organization,and the value of collecting and interpreting geologic information in coal mines to enhance safety and production.The implementation of the methods described above has been proven effective in predicting and mitigating adverse geologic conditions in underground coal mining.Consistent re-evaluation of data collection methods,geologic interpretations,mapping procedures,and communication techniques ensures continuous improvement in the accuracy of predictions and mitigation of adverse geologic conditions.Providing a concise record of the work previously done to track geologic conditions at a mine will allow for the smoothest transition during employee turnover and transitions.With refinements and standardization of data collection methods,such as those described in this paper,along with improvement in technology,the evaluation of adverse geologic conditions will evolve and continue to improve the safety and productivity of underground coal mining. | Mark Van Dyke Ted Klemetti Joe Wickline | 2020 | International Journal of Mining Science and Technology2020，30，1： | 1 |
| 6 | The use of keratin biomaterials derived from human hair for the promotion of rapid regeneration of peripheral nerves显示文摘 | Paulina Sierpinski Jeffrey Garrett Jianjun Ma Peter Apel David Klorig Thomas Smith L. Andrew Koman Anthony Atala Mark Van Dyke | 2007 | Biomaterials2007，，1： | 1 |
| 7 | Controlled fabrication of a biological vascular substitute显示文摘 | Joel Stitzel Jie Liu Sang Jin Lee Makoto Komura Joel Berry Shay Soker Grace Lim Mark Van Dyke Richard Czerw James J. Yoo Anthony Atala | 2005 | Biomaterials2005，，7： | 1 |
| 8 | Effect of longwall-induced subsurface deformations on shale gas well casing stability under deep covers显示文摘This paper presents the results of a 2017 study conducted by the National Institute for Occupational Safety and Health(NIOSH), Pittsburgh Mining Research Division(PMRD), to evaluate the effects of longwall-induced subsurface deformations within a longwall abutment pillar under deep cover. The 2017 study was conducted in a southwestern Pennsylvania coal mine, which extracts 457 m-wide longwall panels under 361 m of cover. One 198 m-deep, in-place inclinometer monitoring well was drilled and installed over a 45 m by 84 m center abutment pillar. In addition to the monitoring well, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the 457 m-wide longwall panel on the south side of the abutment pillar was being mined. Prior to the first longwall excavation, a number of simulations using FLAC3D^(TM) were conducted to estimate surface subsidence, increases in underground coal pillar pressure, and subsurface horizontal displacements in the monitoring well. Comparisons of the pre-mining FLAC3D simulation results and the surface, subsurface,and underground instrumentation results show that the measured in-place inclinometer casing deformations are in reasonable agreement with those predicted by the 3D finite difference models. The measured surface subsidence and pillar pressure are in excellent agreement with those predicted by the 3D models.Results from this 2017 research clearly indicate that, under deep cover, the measured horizontal displacements within the abutment pillar are approximately one order of magnitude smaller than those measured in a 2014 study under medium cover. | Daniel W.H.Su Peter Zhang Mark Van Dyke Todd Minoski | 2019 | International Journal of Mining Science and Technology2019，29，1： | 1 |
| 9 | A naturally derived, cytocompatible, and architecturally optimized scaffold for tendon and ligament regeneration显示文摘 | Patrick W. Whitlock Thomas L. Smith Gary G. Poehling Jeffrey S. Shilt Mark Van Dyke | 2007 | Biomaterials2007，，29： | 1 |
| 10 | Deep cover bleeder entry performance and support loading: A case study显示文摘Several questions have emerged in relation to deep cover bleeder entry performance and support loading:how well do current modeling procedures calculate the rear abutment extent and loading? Does an improved understanding of the rear abutment extent warrant a change in standing support in bleeder entries? To help answer these questions and to determine the current utilization of standing support in bleeder entries, four bleeder entries at varying distances from the startup room were instrumented,observed, and numerically modeled.This paper details observations made by NIOSH researchers in the bleeder entries of a deep cover longwall panel—specifically data collected from instrumented pumpable cribs, observations of the conditions of the entries, and numerical modeling of the bleeder entries during longwall extraction.The primary focus was on the extent and magnitude of the abutment loading experienced by the standing support.As expected, the instrumentation of the standing supports showed very little loading relative to the capacity of the standing supports—less than 23 Mg load and 2.54 cm convergence.The Flac3D program was used to evaluate these four bleeder entries using previously defined modeling and input parameter estimation procedures.The results indicated only a minor increase in load during the extraction of the longwall panel.The model showed a much greater increase in stress due to the development of the gateroad and bleeder entries, with about 80% of the increase associated with development and 20% with longwall extraction.The Flac3D model 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 abutment stress experienced by this bleeder entry design was minimal.The farther away from the startup room, the lower the applied load and smaller the convergence in the entry if all else is held constant.Finally, the numerical modeling method used in this study was capable of replicating the expected and measured results near seam. | Ted M.Klemetti Mark Alexander Van Dyke Ihsan Berk Tulu | 2018 | International Journal of Mining Science and Technology2018，28，1： | 1 |
| 11 | Coal rib response during bench mining: A case study显示文摘In 2016, room-and-pillar mining provided nearly 40% of underground coal production in the United States.Over the past decade, rib falls have resulted in 12 fatalities, representing 28% of the ground fall fatalities in U.S.underground coal mines.Nine of these 12 fatalities(75%) have occurred in room-andpillar mines.The objective of this research is to study the geomechanics of bench room-and-pillar mining and the associated response of high pillar ribs at overburden depths greater than 300 m.This paper provides a definition of the bench technique, the pillar response due to loading, observational data for a case history, a calibrated numerical model of the observed rib response, and application of this calibrated model to a second site. | Morgan M.Sears John Rusnak Mark Van Dyke Gamal Rashed Khaled Mohamed Michael Sloan | 2018 | International Journal of Mining Science and Technology2018，28，1： | 0 |
| 12 | Preliminary rib support requirements for solid coal ribs using a coal pillar rib rating(CPRR)显示文摘Researchers from the National Institute for Occupational Safety and Health(NIOSH)are developing a coal pillar rib rating(CPRR)technique to measure the integrity of coal ribs.The CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal ribs.The CPRR utilizes four parameters:rib homogeneity,bedding condition,face cleat orientation with respect to entry direction,and rib height.All these parameters are measurable in the field.A rib data collecting procedure and a simple sheet to calculate the CPRR were developed.The developed CPRR can be used as a rib quality mapping tool in underground coal mines and to determine the potential of local rib instabilities and support requirements associated with overburden depth.CPRR calculations were conducted for 22 surveyed solid coal ribs,mainly composed of coal units.Based on this study,the rib performance was classified into four categories.A preliminary minimum primary rib support density(PRSD)line was obtained from these surveyed cases.Two sample cases are presented that illustrate the data collection form and CPRR calculations. | Khaled Mohamed Mark Van Dyke Gamal Rashed Morgan MSears Robert Kimutis | 2021 | International Journal of Mining Science and Technology2021，31，1： | 0 |
| 13 | Application of the coal mine floor rating(CMFR)to assess the floor stability in a Central Appalachian Coal Mine显示文摘Estimating the overall floor stability in a coal mine using deterministic methods which require complex engineering properties of floor strata is desirable,but generally it is impractical due to the difficulty of gathering essential input data.However,applying a quantitative methodology to describe floor quality with a single number provides a practical estimate for preliminary assessment of floor stability.The coal mine floor rating(CMFR)system,developed by the University of New South Wales(UNSW),is a rockmass classification system that provides an indicator for the competence of floor strata.The most significant components of the CMFR are uniaxial compressive strength and discontinuity intensity of floor strata.In addition to the competence of the floor,depth of cover and stress notch angle are input parameters used to assess the preliminary floor stability.In this study,CMFR methodology was applied to a Central Appalachian Coal Mine that intermittently experienced floor heave.Exploratory drill core data,overburden maps,and mine plans were utilized for the study.Additionally,qualitative data(failure/non-failure)on floor conditions of the mine entries near the core holes was collected and analyzed so that the floor quality and its relation to entry stability could be estimated by statistical methods.It was found that the current CMFR classification system is not directly applicable in assessing the floor stability of the Central Appalachian Coal Mine.In order to extend the applicability of the CMFR classification system,the methodology was modified.A calculation procedure of one of the CMFR classification system’s components,the horizontal stress rating(HSR),was changed and new parameters were added to the HSR. | Sena Cicek Ihsan Berk Tulu Mark Van Dyke Ted Klemetti Joe Wickline | 2021 | International Journal of Mining Science and Technology2021，31，1： | 0 |
| 14 | Assessing support alternatives for longwall gateroads subject to changing stress显示文摘Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted panel.The stress changes can result in significant deformation of the entries that may include roof sag,rib dilation,and floor heave.Mine operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall face.This paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support alternatives.The research included monitoring of ground and support interaction at several operating longwall mines in the U.S.,analysis and calibration of numerical models that adequately represent the bedded rock mass,and observation of the support systems and their response to changes in stress.The models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic scenarios.The research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress changes.This information is then used to assess the ability of support systems to maintain the stability of the roof.The application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof fall.The method is shown to produce realistic estimates of gateroad entry stability and support performance,allowing alternative support systems to be assessed during the design and planning stage of longwall operations. | Gabriel S.Esterhuizen I.Berk Tulu Dave F.Gearhart Heather Dougherty Mark Van Dyke | 2021 | International Journal of Mining Science and Technology2021，31，1： | 0 |
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