Literatura científica selecionada sobre o tema "Mine roof bolts"
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Artigos de revistas sobre o assunto "Mine roof bolts"
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Zhang, Zhi Jie, Qun-Liang Han, Shao Wei Liu e Ying Ming Li. "Roof Bolts Broken Mechanism and Their Reasonable Construction Structures". Key Engineering Materials 306-308 (março de 2006): 37–42. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.37.
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Since the broken phenomenon is always appeared in the roof of mine roadway, it largely affects the roadway’s roof stability. With Material Mechanics theory, the authors expound bolt tail subjected to no center load action and roof bolt broken mechanism while roadway is supported with bolts. By theoretical analysis and Lab test, the paper puts forward a kind of new type bolts which may prevent bolt tails from being broken, bolt construction structure’s pattern, and bolt made technology. It is illustrated that the reasonable grading relationship between bolt body’s iameter and bolt tail’s screw diameter. At same time, the authors compare disturbed values of the thick tail metal bolt and common bolt under the load action. It is verified that roof bolt broken problem may be solved with new type’s thick tail bolt. Therefore, the new type bolts have a wide application in the future.
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Tang, Bin, Hua Cheng, Yongzhi Tang, Zhishu Yao, Chuanxin Rong, Weipei Xue e Jian Lin. "Application of a FBG-Based Instrumented Rock Bolt in a TBM-Excavated Coal Mine Roadway". Journal of Sensors 2018 (17 de setembro de 2018): 1–10. http://dx.doi.org/10.1155/2018/8191837.
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Rock bolts have been widely applied with roadway excavation in underground coal mines to prevent roadway collapse and improve the stability of roadway surrounding rocks. Overloading and failures of rock bolts could result in accidents or casualties in coal mine roadways. Consequently, monitoring axial forces and work conditions of rock bolts plays an increasingly important role in ensuring safe operations of underground coal mines. Conventional mechanical or electronic rock bolt monitoring systems are typically affected by electromagnetic interference, corrosive groundwater, and dusty circumstance in underground working sites. This work proposed a FBG-based instrumented rock bolt. Quasi-distributed FBG sensors were installed on a slotted rock bolt and encapsulated by epoxy resin that was used to fix FBG sensors on the rock bolt and protect FBG sensors from damage. The FBG sensors were calibrated before the in situ application. Monitoring results indicated that the axial forces of rock bolts installed on the roof of the roadway were higher than that of others, and the maximum axial forces of each rock bolt were typically detected near the middle portion of rock bolts. A real-time and accurate rock bolt monitoring system was established by integrating instrumented rock bolts to the existing monitoring system of the coal mine.
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Krukovskyi, Oleksandr, Yurii Bulich e Yuliia Zemlianaia. "Modification of the roof bolt support technology in the conditions of increasing coal mining intensity". E3S Web of Conferences 109 (2019): 00042. http://dx.doi.org/10.1051/e3sconf/201910900042.
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The modification of the technology roof bolt supporting of mine workings in the conditions of increasing the coal mining intensity has been made. The technological schemes have been developed for the phased construction of roof bolting and frame support. This schemes make it possible to temporarily postpone the setting of frames in the mine working face, reduce the time and labour intensity for covering with a grid of the mine working arch and setting the bolts, as well as to increase the safety. The analysis of changes in the stress state of the border massif during the phased construction of roof bolting and frame support has been made. It is shown that the technology of phased construction of roof bolting and frame support ensures the maintaining a stable state of host rocks. In addition, the time between the extraction of the coal-rock mass and the setting of the primary support, as well as the distance between the face and the first row of roof bolts has been reduced to a minimum. The suggested approach makes possible to ensure the rate of preparatory mine workings development that are necessary for the intensification coal mining.
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Bondarenko, Volodymyr, Iryna Kovalevska, Oleksandr Husiev, Vasyl Snihur e Ildar Salieiev. "Concept of workings reuse with application of resource-saving bolting systems". E3S Web of Conferences 133 (2019): 02001. http://dx.doi.org/10.1051/e3sconf/201913302001.
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The new support patterns have been revealed for controlling the combinations of the roof rocks strengthening processes in extraction mine workings with combined roof-bolting systems. It has been established that in adjacent roof rocks, by means of a combination of rope bolts and resin-grouted roof bolts, an armored and rock plate is formed, the high load-bearing capacity of which is achieved by maintaining the horizontal thrust forces that reduces the concentrations of all the stresses components to a level many times lower than the strength characteristics of the lithotypes. The criterion has been substantiated for assessing the resistance level of roof-bolts as a part of the combined roof-bolting system, which is used for determination of the most important geomechanical factors in terms of the system loading degree. The patterns have been established of a degree of loading the roof-bolts being a part of the combined roof-bolting system from the main influencing geomechanical factors. The calculated expressions have been obtained to determine the needed parameters for effectively strengthening the roof in workings by a combined roof-bolting system. The mine experiment analysis has been performed as well.
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Tsibaev, Sergey, Alexey Renev, Rinat Zainulin e Alexander Kucherenko. "Analysis of rock mass and anchor support elements deformations during the long-term maintenance of mine workings". E3S Web of Conferences 174 (2020): 01001. http://dx.doi.org/10.1051/e3sconf/202017401001.
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The results of instrumental and visual assessment of near-rock massif and anchor support elements state in the conditions of long-term maintenance of mine workings has been presented. Particular attention is paid to underground mines in a flooded state. The result of various profiles fixing bolts strength tests of in the roof and sides of the workings has been presented. It has been established that the probability distribution of the anchoring bolts force in the holes in roof of the workings obeys the normal distribution tendency. The result of a radar survey of roof rocks using the Georadar OKO-2 has been analyzed. It was revealed that the height of the stratification of rocks in the mine workings roof varies from 0.2 m to 2.25 m, a comparison is made with the theoretical height of the collapse arch. The propensity of the near rock massif to water saturation has been estimated, the height of the water saturation of the roof rocks has been established. It has been established that the height of moisture depends on the arch of rock stability formed during the survey period. It has been found that water saturation of the rocks leads to a decrease in the specific cohesion of the resin capsules bonding composition with the walls of the hole by 55-67% in roof and by 72% in walls of mine workings.
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Gu, Shitan, Bangyou Jiang, Gensheng Wang, Huabin Dai e Mingpeng Zhang. "Occurrence Mechanism of Roof-Fall Accidents in Large-Section Coal Seam Roadways and Related Support Design for Bayangaole Coal Mine, China". Advances in Civil Engineering 2018 (11 de julho de 2018): 1–17. http://dx.doi.org/10.1155/2018/6831731.
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This study focused on large-scale roof-fall accidents occurred in large-section coal seam roadways of Bayangaole Coal Mine, Inner Mongolia, China, and investigated the occurrence mechanism of roof-fall and the related supporting control method in detail. Firstly, the fracture characteristics of the surrounding rocks on the roadway roof were measured using a stratum detector. The results showed that the roadway roof underwent the most severe failure with a maximum deformation of 3.53 m; the bedding separation and fracture zones were distributed at irregular intervals. Accordingly, the entire stratum was separated into several thin sublayers, significantly reducing the stability of roof. In addition, the roof medium grained sandstone of roadway is water-rich strata, and water aggravates the damage of roof. Next, the mechanism of the occurrence of roof-fall accidents in the roadway was elucidated in detail. The following three reasons are mainly attributed to the occurrence of roof-fall accidents: (i) effects of mining-induced stress and tectonic stress, (ii) existence of equipment cavern on the side of roadway, and (iii) unreasonable support parameters. On that basis, a new supporting design is proposed, including a more reasonable arrangement of anchor cables and bolts, bolts with full-length anchorage which are applicable in cracked and water-rich roadway, high-strength anchor cables, and crisscrossed steel bands. Moreover, high pretightening force was applied. Finally, a field test was performed, and the mining-induced roof displacement and stress on anchor cable (bolt) were monitored in the test section. The maximum roof displacements at the two monitoring sections were 143 mm and 204 mm, respectively, far smaller than the roadway’s allowable deformation. Moreover, the stress on roof anchor cables (bolts) was normal, and no anchorage-dragging and tensile failure phenomena were observed. The monitoring data indicated that the new supporting design was remarkable on the control of large-section coal seam roadway roof deformation.
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Ren, Heng, Yongjian Zhu, Ping Wang, Peng Li, Yuqun Zhang, Xizhi Wang e Yingying Li. "Classification and Application of Roof Stability of Bolt Supporting Coal Roadway Based on BP Neural Network". Advances in Civil Engineering 2020 (16 de novembro de 2020): 1–9. http://dx.doi.org/10.1155/2020/8838640.
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In view of the frequent occurrence of roof accidents in coal roadways supported by bolts, the widespread application of bolt support technology in coal roadways has been restricted. Through on-site investigation, numerical analysis, and other research methods, 6 evaluation indicators were determined, and according to the relevant evaluation factors and four types of coal roadway roof stability, a neural network structure for roof stability prediction was constructed to realize the quantitative prediction of the roof stability of bolt-supported coal roadway. The method of adding momentum is used to improve the BP neural network algorithm. After passing the simulation test, it is applied to the field experiment of the roof stability classification. In order to facilitate on-site application, on the basis of the established BP neural network prediction model, a coal mine roof stability classification software recognition system was developed. Using the developed software system, the stability of coal roadway roof is classified into mine, coal seam, and region. According to the recognition result, the surfer software is used to draw the contour map of the stability of the roof of each coal mining roadway. The classification results are consistent with the actual situation on site.
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Skrzypkowski, Krzysztof. "Evaluation of Rock Bolt Support for Polish Hard Rock Mines". E3S Web of Conferences 35 (2018): 01006. http://dx.doi.org/10.1051/e3sconf/20183501006.
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The article presents different types of rock bolt support used in Polish ore mining. Individual point resin and expansion rock bolt support were characterized. The roof classes for zinc and lead and copper ore mines were presented. Furthermore, in the article laboratory tests of point resin rock bolt support in a geometric scale of 1:1 with minimal fixing length of 0.6 m were made. Static testing of point resin rock bolt support were carried out on a laboratory test facility of Department of Underground Mining which simulate mine conditions for Polish ore and hard coal mining. Laboratory tests of point resin bolts were carried out, especially for the ZGH Bolesław, zinc and lead “Olkusz – Pomorzany” mine. The primary aim of the research was to check whether at the anchoring point length of 0.6 m by means of one and a half resin cartridge, the type bolt “Olkusz – 20A” is able to overcome the load.The second purpose of the study was to obtain load – displacement characteristic with determination of the elastic and plastic range of the bolt. For the best simulation of mine conditions the station steel cylinders with an external diameter of 0.1 m and a length of 0.6 m with a core of rock from the roof of the underground excavations were used.
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Zhang, Xiaoqian, Heng Zhang e Chengmin Wei. "Numerical Simulation Study on the Influence of Mine Earthquake on the Bolt Stress". Shock and Vibration 2021 (17 de julho de 2021): 1–12. http://dx.doi.org/10.1155/2021/6364718.
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Mine earthquake, as an underground disaster that occurs frequently, has a great impact on coal mine roadway and support. The stability analysis of the bolt support in roadway under different mine earthquake magnitudes is a key issue to be solved urgently in mining fields. This paper attempted to simulate the occurrence state of mine earthquake with explosive blasting process and verified it with actual coal mine microseismic monitoring data. ANSYS/LSDYNA software was used to analyze the impact of magnitude and location of mine earthquake hypocenter on the stability of bolt support and the dynamic stress characteristics of bolt. The results showed that with the increase in source energy of mine earthquake, the damage location of bolt mainly appears in the front of bolt and the loading position has no obvious change, but there is stress wave superposition effect, which deepens the damage of bolt. The bolts in the middle of the lane and the middle of the roof are greatly affected, so the support strength should be strengthened in these places. In addition, this paper compared the safety factor of bolt and the supporting effect of different schemes from three aspects such as roof subsidence, axial stress of bolt, and safety factor of bolt and then put forward a more economical and effective supporting scheme.
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Khomenko, Oleh, Maksym Kononenko, Ihor Kovalenko e Denys Astafiev. "Self-regulating roof-bolting with the rock pressure energy use". E3S Web of Conferences 60 (2018): 00009. http://dx.doi.org/10.1051/e3sconf/20186000009.
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The perspective of discovery of zonal disintegration phenomenon of rocks around underground mine workings is analyzed. The methodological stages for research of this phenomenon are shown. The physics of zonal disintegration of rocks around underground mine workings is disclosed. There are described the possibilities of advanced entropy method and developed energy method that allow to investigate a phenomenon of zonal capsulation of underground mine workings. The sequence of research of this phenomenon parameters is presented. The order of choice of stable shape and resource-saving support in underground mine workings is substantiated, for the deep horizons of the Kryvorizkyi Iron-Ore Basin mines. The method of parameters calculation of self-regulating roof-bolting in underground mine workings is substantiated, which allows to use the rock pressure energy. The design of a self-regulating roof-bolting is developed, which allows applying metal, polymer and rope bolts. The economic efficiency of rock pressure energy usage is substantiated in case of support setting at great depths in underground mine workings.
Teses / dissertações sobre o assunto "Mine roof bolts"
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Reisterer, Jonathan Richard. "The Interaction of Active or Passive Roof Bolts, Stress Conditions, and the Immediate Roof Strata in a Longwall Mine in the United States". OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/697.
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Safety is the most important aspect to the mining industry. Research having a direct and positive impact on mine safety is always needed and should be supported. There are several different types of primary roof supports that are used to try to maintain stable mine workings in order to extract the coal safely. The majority of roof bolts installed annually in underground coal mines in the USA use resin cartridges (Tadolini, 2006). The standard roof bolt used is a fully grouted resin rebar bolt. This is considered a passive (un-tensioned) support. Technological advances in roof support anchored with resin grout systems have resulted in the development of supports that are active (tensioned during installation). Generally it is thought that active anchors are superior in performance as roof support except in highly laminated weak roof. The assumption is that since an active system applies some pre-tension to the roof, it will provide a more stable roof beam. There is, however, a lack of real data to back up this perception. A systematic attempt is through this project that addresses this knowledge gap. Without a clear idea on how different roof bolt systems work in-situ, the consequences could have a significant impact on the safety of the miners working underground as well as production costs. Supports are now often only chosen based on perceived ideas instead of real data. Such assumed superior performance of the support system could lead to false economy. Essentially, it needs to be demonstrated to what degree or under what conditions, if any, these technological advances in roof support improve ground conditions and opening stability and ultimately improve the safety of the miners. There is an argument regarding whether passive bolts could truly be better than active bolts. The focus is centralized towards a cost and performance issue. The overall goal of the proposed project was to develop an understanding of the interaction between different roof bolt types and the immediate strata in a longwall headgate as the longwall face progresses. In order to monitor the interactions between the strata and roof bolts, specially instrumented bolts were installed with six strain gauges that were electronically accessed. A look into the initial bolt loads was used to compare three different bolt types (both tensioned and untensioned) upon installation. These loads continued to be monitored and analyzed as the longwall face approached and passed the location of the instrumented bolts. Along with analyzing instrumented bolt data compared to a passing longwall face, a limited finite element model was set up within Flac3D to represent real conditions, and compare the in situ data collected to the computer outputs in order to establish beginning phases of validating the results.
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Weckert, Steven Mining Engineering Faculty of Engineering UNSW. "Anchorage and encapsulation failure mechanisms of rockbolts ??? stage 2". Awarded by:University of New South Wales. School of Mining Engineering, 2003. http://handle.unsw.edu.au/1959.4/19219.
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The Fully Encapsulated Resin Bolt (FERB) is widely utilised for strata control and ground support in civil and mining applications worldwide, with approximately 6 million installed per annum by the Australian coal mining industry. Independent studies have concluded that 30-35% of these rockbolts, which represents an annual expenditure of $40 million, are ineffective. The anchorage and failure mechanisms of FERB are yet to be quantified, and support systems are designed primarily from empirical rather than scientific methods. There are no standardised methods of assessing FERB components, installation techniques and support behaviour. The majority of research into FERB support systems remains commercial intellectual property, with little information released into the public domain. This thesis investigated several variables of FERB support systems, and also examined differences between field and laboratory pull-out test load distributions. This research was conducted in two phases, with Phase 1 seeking standardised methodology and repeatability in results, while Phase 2 further refined Phase 1 methods and extended the range of tests. The results in both phases were encouraging, with reasonable repeatability attained in all testing series. The findings included: ??? Annulus Thickness: There was little change in load capacity with small annulus thickness, however the maximum peak load (MPL) significantly reduced once annulus thickness exceeded 4mm ??? Resin Installation Spin Time: Underspinning of cartridge resin was found to have an insignificant effect on rockbolt load/deformation characteristics. Overspinning, however, led to a dramatic reduction in anchorage performance with a lessening in both MPL and stiffness ??? Rockbolt Load Transfer: The magnitude of an applied load reduced to zero along the length of the rockbolt, being greatest nearest the rock free surface (the point of load application). An exponential reduction was found when tested in the manner of laboratory tests, with the loading jack reacting against the free surface. This reduction was linear when the load was applied as in the field, with no load placed on the free surface This basic investigation into FERB support systems has validated many empirical understandings of rockbolts, while highlighting the need for further testing into several key areas.
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Sinha, Sankhaneel. "ANALYSES FOR DESIGN AND SUPPORT OF COAL MINE INTERSECTIONS". OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/2059.
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Rock bolts have been extensively used as a support element in coal mines in the US for about 40 years. Longwall development and partial extraction room-and-pillar mining systems now rely heavily on fully-grouted roof bolts as the primary support with as needed inclined bolts, trusses, and cable bolts as secondary support. These two coal mining systems develop 3- and 4-way intersections during extraction processes. A study of Illinois (2004-2008) and US coal mines found that over 70% of roof falls occurred at intersections. It is therefore necessary to perform additional research in stress and displacement distributions around intersections and then design support systems to improve stability of intersections. This thesis research, in cooperation with a bolt supplier and NIOSH, analyses the stress and strain redistribution in and around intersections in typical lithologies in the Illinois Basin coal mines with the goal to develop a better understanding of failure initiation and propagation mechanisms with and without roof supports. Analyses were corroborated with field observations wherever possible. Non-linear continuum analyses using the Generalized Hoek-Brown failure criterion with rock mass properties is the foundation for these analyses. The first task (Task 1) toward these goals was to develop rock mass properties from available laboratory data using estimates of Geological Strength Index (GSI) for different lithologies. An important subtask was to perform an error analysis in estimates of rock mass properties assuming an amount of error in GSI estimates. Analyses and field observations were done for typical 4-way intersections at two mines in southern Illinois operating at depths of 150 m and 80 m, respectively in the No. 6 coal seam, which averages 1.8 m in thickness. Pre-mining horizontal stresses of 7.58 MPa and 4.13 MPa were applied in the E-W and N-S directions. These coal companies provided geologic logs and rock mechanics data for roof and floor strata. Rock mass engineering properties for different roof and floor lithologies were developed using estimated values of Geological Strength Index (GSI), and Hoek-Brown (H-B) rock mass failure parameters. A recent laboratory study provided normal and shear stiffness properties of the immediate roof interfaces within the bolting range of 1.8 m. MSHA-approved roof support plans were used for initial modeling. Short Encapsulation Pull Test (SEPT) data provided by bolt suppliers in the region were used to assign bolting system stiffness and strength parameters. Task 2 analyzed normal and shearing stresses and strains in and around mine intersections for typical pre-mining stress fields and then identified critical areas of failure initiation and progressive failure propagation. Failure initiation was hypothesized to occur for critical values of compressive (1 mm/m), tensile (0.5 mm/m), and shearing (0.5 mm/m) strains based on a review of laboratory stress-strain properties. This approach allows quantifying areas in and around an intersection where failures are likely to initiate with and without artificial supports. It computes three reinforcement factors with and without supports: reinforcement against tensile (RFT), compressive (RFC) and shearing (RFSS) strains. Task 3 assessed the performance of currently practiced roof support plans and identified where inadequacies exist and how they could be improved through spatial distribution of supports and their characteristics. Analyses were completed for two mines with one orientation of pre-mining horizontal stress field. The next logical step (Task 4) was to extend analyses in Task 3 to assess the effect of maximum compressive stress orientation in relation to entry direction (0o, 30o, 60o & 90o) and different cut sequences and their effect on changes in failure initiation and failure propagation mechanisms. Numerical analyses have shown that stress and strain distributions are significantly different when the cut sequence is included in models. For a horizontal stress ratio of two (2), the 60o orientation provided maximum stability. Separate models with all cuts excavated simultaneously corresponded well with the well-established NIOSH software AHSM and previous research. The effect of cut sequence combined with the directional effect of pre-mining stresses becomes evident from the dissimilar results. A separate statistical study was conducted on 211 SEPT test data provided by a roof support manufacturer and marketing company in the region. Goals were to analyze the database for grip factor (GF) and anchorage stiffness (AS) characteristics using histograms and frequency distributions and, perform regression analyses to relate GF and AS values on the basis of height above coal seam and bolt diameter. Results were used for one stochastic run with variable GF and AS values assigned to different bolts in a roof control plan. Results indicated Gamma distribution best fitted AS and GF data. It was thought that the reinforcement factor for such a bolting layout would be more realistic than assigning a single value of GF and AS to bolts in the model.
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Kostecki, Todd. "The Instrumentation of Primary Roof Bolts in a Room-and-Pillar Mine and the Modeling of their Performance". OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1120.
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This thesis is directed towards the comparison of active and passive bolts systems to reveal which system shows the most favorable behavior for improved performance, safety and cost. This was achieved through the incorporation of new technologies, field data, numerical modeling and established theories in ground control analysis. All in all, a better understanding of the quasi-static behavior of underground coal mine roofs has been attained. Over the summer of 2010, the Department of Mining and Mineral Resource Engineering at Southern Illinois University Carbondale, in conjunction with Andy Hyett of YieldPoint Inc., Peabody and the National Institute of Occupational Safety and Health (NIOSH), installed over one hundred and seventy instrumented extensometers, closure meters, shear-meters, passive rebar roof bolts, tension rebar roof bolts, and double lock rebar roof bolts at three coal mines. Two of the three coal mines were room-and-pillar mines and the other a longwall mine. Data was routinely collected over a nine-month period to analyze shearing, dilation, and axial bolt loading occurring within the rock mass, and entry closure occurring between the excavation hanging-wall and foot-wall. Based on bolt loadings, shear, axial behavior and statistical analysis, initial results indicate that active roof bolts do not show superior performance for the added cost. Active bolts seem to show no difference from passive bolts in the initial loading phase either, indicating that tension bleed-off is a concern soon after installation; however, this observation was not captured, as the data loggers were not intrinsically safe. Considering the modeling results, the trends in axial loading seem to be calibrated but the magnitudes are not. Computer modeling also shows the potential to accurately model in situ bolt performance; however, challenges remain in obtaining a good match between numerical modeling and field observations.
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Buys, B. J. "Rock bolt condition monitoring using ultrasonic guided waves". Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-06222009-135318/.
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Nutakor, David. "Design and evaluation of a virtual reality training system for new underground rockbolters". Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Nutakor_09007dcc80672480.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2008.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 1, 2009) Includes bibliographical references (p. 229-234).
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Bylapudi, Gopi. "CORROSION OF ROCK ANCHORS IN US COAL MINES". OpenSIUC, 2010. https://opensiuc.lib.siu.edu/theses/287.
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The mining industry is a major consumer of rock bolts in the United States. Due to the high humidity in the underground mining environment, the rock bolts corrode and loose their load bearing capacity which in turn reduces the life expectancy of the ground support and, thus, creates operational difficulties and number of safety concerns [1]. Research on rock anchor corrosion has not been adequately extensive in the past and the effects of several factors in the mine atmosphere and waters are not clearly understood. One of the probable reasons for this lack of research may be attributed to the time required for gathering meaningful data that makes the study of corrosion quite challenging. In this particular work underground water samples from different mines in the Illinois coal basin were collected and the major chemical content was analyzed and used for the laboratory testing. The corrosion performance of the different commercial rock anchors was investigated by techniques such as laboratory immersion tests in five different corrosion chambers, and potentiodynamic polarization tests in simulated ground waters based on the Illinois coal basin. The experiments were conducted with simulate underground mining conditions (corrosive). The tensile strengths were measured for the selected rock anchors taken every 3 months from the salt spray corrosion chambers maintained at different pH values and temperatures. The corrosion potential (Ecorr), corrosion current (Icorr) and the corresponding corrosion rates (CR) of the selected commercial rock bolts: #5, #6, #6 epoxy coated and #7 forged head rebar steels, #6 and #7 threaded head rebar steels were measured at the solution pH values of 5 and 8 at room temperature. The open circuit potential (OCP) values of the different rock anchors were recorded in 3 selected underground coal mines (A, B & C) in the Illinois coal basin and the data compared with the laboratory electrochemical tests for analyzing the life of the rock anchors installed in the mines with respect to corrosion potential and corrosion current measured. The results of this research were statistically validated. This research will have direct consequence to the rock related safety. The results of this research indicate that certain corrosive conditions are commonly found in mines but uniform corrosion (around 0.01-0.03mm loss per year across the diameter) is generally not considered a serious issue. From this study, longer term research for long-term excavation support is recommended that could quantify the problem depending on the rock anchor used and specific strata conditions.
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Bylapudi, Gopi. "STRESS CORROSION CRACKING OF REBAR ROOF BOLTS IN U.S. UNDERGROUND COAL MINES - A PRELIMINARY STUDY". OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1573.
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According to the National Institute of Occupational Safety and Health (NIOSH), about 100 million rock anchors were installed in the USA mining industry during 1999 (Dolinar, 2000). The rock bolt usage in US coal mining industry fell from 85 million in the year 1988 to 68 million by 2005 (Tadolini, 2006), and is assumed to be close to that number of rock anchors consumed currently since, the tonnage from underground is almost the same. Most underground coal mines have conditions such as moisture in the atmosphere, ground water with different chemical contents that are conducive for corrosion of rock anchors and ancillaries (such as plates), and the effects of this on the performance of the anchors had been researched in the US to an extent from the past research at Southern Illinois University Carbondale (SIUC). In addition to the general corrosion like pitting and crevice, stress corrosion adds to the process a potentially serious threat and results in material failure underground due to stress corrosion cracking (SCC) yet the effects are not fully understood in the USA. The results of this research therefore will have a positive and direct effect on rock related safety. During this research project in situ specific tests were conducted with bolts to try and determine the corrosion potential in a specific coal-mining region. The coal mining areas were divided into three regions and were named as East, Mid-West and West respectively. To enhance the value/importance of the field data collected from the mines, a metal mine and a salt mine (two non-coal mines) were included in the plan and the data analysis proved that the methodology developed for determining the corrosion potential underground is applicable to any underground mines. The Insitu studies include water samples collection and analysis and open circuit potential (OCP/Eoc) testing and analysis. Open Circuit Potential (OCP) data were recorded to estimate probability of active corrosion. Hypothetically, probability of active corrosion is lower if the actual OCP of roof bolts in the mine is less than the characteristic OCP of the steel grade, and vice versa. The effects of certain factors such as the roof condition, reference distance (distance between bolt and reference electrode) on the open circuit potential data during the measurements were studied to ensure its impact on the corrosion potential determination technique developed. The findings from this research helps standardize the corrosion potential determination methodology. The preliminary study of stress corrosion cracking of the subject test sample (Grade 60 rebar roof bolt) was conducted in this research work. The experimental study invloves testing a complete roof bolt in the mine simulated environment. The mine simulated environment in the test cell consists of the roof strata material collected from the mine site with continuous flow of water at slower and varaible flow rate (0 to 3 ml/minute) with pH in the range of 7.5 to 9.0. The results showed that stress corrosion could be very serious problem when it comes to long term mining applications. The stress corrosion test cell developed and tested was proved to be significant in conducting the long term stress corrosion tests. The strength results of the Grade 60 rebar roof bolt tested had a significant strength loss after 3 months of testing in the stress corrosion cell. Hence, more SCC studies are deemed necessary to evaluate the seriousness of the problem and if possible eliminate it.
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Weckert, Steven. "Anchorage and encapsulation failure mechanisms of rockbolts - stage 2 /". 2003. http://www.library.unsw.edu.au/~thesis/adt-NUN/public/adt-NUN20040317.085411/index.html.
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Thesis (M. E.)--University of New South Wales, 2003."The precursor to this thesis was an industry-sponsored project, completed in 2000 by C. Offner at the School of Mining Engineering, UNSW ; this project is referred to as the Stage 1 project"--summary. Also available online.
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Canbulat, Ismet. "Evaluation and design of optimum support systems in South African collieries using the probabilistic design approach". Thesis, 2008. http://upetd.up.ac.za/thesis/available/etd-07282008-161030.
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Thesis (PhD.(Mining Engineering)--University of Pretoria, 2008.Summary in English. On title page: Submitted in partial fulfilment of the requirements for the degree Philosophiae Doctor in the Faculty of Engineering, Built Environment and Information Technology, University of Pretoria. Includes bibliographical references.
Livros sobre o assunto "Mine roof bolts"
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Pettibone, Howard C. Avoiding Anchorage problems with resin-grouted roof bolts. Pittsburgh, Pa: U.S. Dept. of the Interior, Bureau of Mines, 1987.
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Serbousek, M. O. Linear load-transfer mechanics of full-grouted roof bolts. Pittsburgh, Pa: U.S. Dept. of the Interior, Bureau of Mines, 1987.
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Johnston, Joanne L. Instrumentation procedures for fully grouted rock bolts. [Washington, D.C.?]: United States Dept. of the Interior, Bureau of Mines, 1993.
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Johnston, Joanne L. Instrumentation procedures for fully grouted rock bolts. Washington, D.C: United States Dept. of the Interior, Bureau of Mines, 1993.
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Johnston, Joanne L. Instrumentation procedures for fully grouted rock bolts. [Washington, D.C.?]: United States Dept. of the Interior, Bureau of Mines, 1993.
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Tadolini, Stephen C. Transfer mechanics of full-column resin-grouted roof bolts. Washington, D.C. (2401 E St., N.W., MS #9800, Washington 20241-0001): U.S. Dept. of the Interior, Bureau of Mines, 1991.
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Martin, L. A. Installation and safety practices for cable bolts in underground mines. [Pittsburgh, PA]: U.S. Dept. of the Interior, Bureau of Mines, 1996.
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Hansen, J. S. Pull and creep tests on gypsum-bonded roof bolts. Pittsburgh, Pa: U.S. Dept. of the Interior, Bureau of Mines, 1985.
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Bartels, John R. Comparative laboratory evaluation of resin-grouted roof bolt elements. Washington, D.C: U.S. Dept. of the Interior, Bureau of Mines, 1985.
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Fraley, J. E. Bolt anchorage with gypsum-plaster water capsule cartridges. [Avondale, Md.]: U.S. Dept. of the Interior, Bureau of Mines, 1987.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Mine roof bolts"
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Tejeswaran, K. M., Ch S. N. Murthy e B. M. Kunar. "Numerical Investigation on Factors Affecting the Performance of Roof Bolts for Continuous Miner Working". In Learning and Analytics in Intelligent Systems, 383–93. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-24314-2_47.
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Roko, Raoul O., e Jaak J. K. Daemen. "A laboratory study of bolt reinforcement influence on beam building, beam failure and arching in bedded mine roof". In Rock Bolting, 205–17. London: Routledge, 2021. http://dx.doi.org/10.1201/9780203740507-19.
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UNRUG, K. F. "Monitoring of the Performance of Mechanical Roof Bolts in an Appalachian Coal Mine". In Advances in Mining Science and Technology, 333–44. Elsevier, 1987. http://dx.doi.org/10.1016/b978-0-444-42845-5.50033-4.
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Bondarenko, V., I. Kovalevska, H. Symanovych, M. Barabash, V. Chervatiuk, O. Husiev e V. Snihur. "Analysis of Rock Pressure Manifestation in the Preparatory Mine Workings at the Structural Transformation of Enclosing Rocks by the Roof-Bolt Strengthening". In Combined Roof-Bolting Systems of Mine Workings: Monograph, 6–16. CRC Press, 2020. http://dx.doi.org/10.1201/9781003081432-3.
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Dutt, Avi. "A new comprehensive method for designing roof bolt support system forunderground coal mines". In Technical and Geoinformational Systems in Mining, 317–24. CRC Press, 2011. http://dx.doi.org/10.1201/b11586-53.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Mine roof bolts"
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Dunning, John S. "Smart roof bolts for underground mines/storage facilities". In SPIE's 9th Annual International Symposium on Smart Structures and Materials, editado por Anna-Maria R. McGowan. SPIE, 2002. http://dx.doi.org/10.1117/12.475093.
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Peterson, Jeffrey Shawn, Peter G. Kovalchik e David Yantek. "Development of Roof-Bolting Machine Bit and Chuck Isolators for Drilling Noise Reductions". In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11226.
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Among underground coal miners, hearing loss remains one of the most common occupational illnesses. In response, the National Institute for Occupational Safety and Health (NIOSH) conducts research to reduce the noise emission of various underground coal mining equipment, an example of which is a roof bolting machine (RBM). After the removal of coal or rock, the remaining strata may be subject to fall, either from overhead (the roof) or from the side (the rib). One method used in underground coal-mines to prevent failures requires the installation of roof bolts. The roof bolting machine operator trams the machine to the required location, drills a hole into the strata, and then installs a roof bolt, supporting the roof or the rib, as the case may be. Field studies support the premise that, on average, drilling noise is the loudest noise that a roof bolting machine operator would be exposed to and contributes significantly to the operators’ noise exposure. NIOSH has determined that the drill steel radiates a significant amount of noise during drilling. NIOSH is developing bit and chuck isolators to reduce vibration, and thus noise radiation of the drill steel, with the longer-term goal of reducing roof bolting machine operator noise exposure. Laboratory testing has shown that operator ear sound pressure levels may be reduced by 3 to 7 dB(A), depending upon the test configuration and drilling media.