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Journal articles on the topic 'Mine roof bolts'
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1
Zhang, Zhi Jie, Qun-Liang Han, Shao Wei Liu, and Ying Ming Li. "Roof Bolts Broken Mechanism and Their Reasonable Construction Structures." Key Engineering Materials 306-308 (March 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.
2
Tang, Bin, Hua Cheng, Yongzhi Tang, Zhishu Yao, Chuanxin Rong, Weipei Xue, and Jian Lin. "Application of a FBG-Based Instrumented Rock Bolt in a TBM-Excavated Coal Mine Roadway." Journal of Sensors 2018 (September 17, 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.
3
Krukovskyi, Oleksandr, Yurii Bulich, and 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.
4
Bondarenko, Volodymyr, Iryna Kovalevska, Oleksandr Husiev, Vasyl Snihur, and 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.
5
Tsibaev, Sergey, Alexey Renev, Rinat Zainulin, and 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.
6
Gu, Shitan, Bangyou Jiang, Gensheng Wang, Huabin Dai, and 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 (July 11, 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.
7
Ren, Heng, Yongjian Zhu, Ping Wang, Peng Li, Yuqun Zhang, Xizhi Wang, and Yingying Li. "Classification and Application of Roof Stability of Bolt Supporting Coal Roadway Based on BP Neural Network." Advances in Civil Engineering 2020 (November 16, 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.
8
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.
9
Zhang, Xiaoqian, Heng Zhang, and Chengmin Wei. "Numerical Simulation Study on the Influence of Mine Earthquake on the Bolt Stress." Shock and Vibration 2021 (July 17, 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.
10
Khomenko, Oleh, Maksym Kononenko, Ihor Kovalenko, and 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.
11
Majcherczyk, Tadeusz, Zbigniew Niedbalski, Piotr Małkowski, and łukasz Bednarek. "Analysis of Yielding Steel Arch Support with Rock Bolts in Mine Roadways Stability Aspect." Archives of Mining Sciences 59, no. 3 (October 20, 2014): 641–54. http://dx.doi.org/10.2478/amsc-2014-0045.
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Abstract The result of the search for new technological solutions in the field of support for roadways in coal mines has in recent years been the widespread use of steel arch with rockbolt support systems. The efficiency of these systems is affected among other things by the option of installing rock bolts after the actual driving the mine roadway, the increased load capacity that these systems can support, and their resistance to dynamic weight. Large variation in the way that these steel arch support can be connected using different types of rock bolts necessitates mining research revealing the effectiveness of such solutions. Although the steel arch with rockbolt support system is used in the majority of European coal mines, it is still not possible to apply templates of schemes due to the diversity of geological and mining conditions. Therefore, throughout a period of several years, the authors of this article conducted research in situ under conditions of different schemes related to connecting arched support frames with rock bolts, with only selected results being presented in the article. The measurements of convergence, load supported by the system frame, load supported by the rock bolts, and the stratification of roof rocks were analyzed, carried out in two roadways with yielding steel arch support in which strand bolts were applied. The article also proposes the index for working maintenance nuw, used in preliminarily assessing the stability of a given working with a limited number of data concerning geomechanical conditions. Additionally considered are empirical methods used in Poland for designing steel arch with rock bolt support systems. The results of mine research indicate that strengthening yielding steel support with strand bolts through steel beams maintains the stability of a roadway, even when exposed to the exploitation stress. Aside from the impact of exploitation, deformations of the support system are negligible, despite the fact that the tensile forces acting on the rock bolts can reach values of up to 160 kN. Under favorable geological and mining conditions, support system frames can be spread up to 1.5 m apart when using rock bolts between them. The conducted measurement of convergence during a three year period revealed a compression amounting to a few centimeters. The results obtained by the research fully confirm the effectiveness of combined yielding steel arch with rock bolt support systems under different mining conditions.
12
Yang, Houqiang, Changliang Han, Nong Zhang, Yuantian Sun, Dongjiang Pan, and Changlun Sun. "Long High-Performance Sustainable Bolt Technology for the Deep Coal Roadway Roof: A Case Study." Sustainability 12, no. 4 (February 13, 2020): 1375. http://dx.doi.org/10.3390/su12041375.
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High-efficiency maintenance and control of the deep coal roadway roof stability is a reliable guarantee for safe production and sustainable development of a coal mine. With belt haulage roadway 3108 in MenKeqing coal mine as the research background, in situ investigation, theoretical analysis, numerical simulation, and engineering practice were carried out to reveal the law of improving the bearing state of bolts by increasing the thickness of the roof anchoring layer. Also, the mechanism of the high-efficiency and long anchoring of the roof is revealed. Results show that increasing thickness of the roof anchorage layer could mobilize deep rock mass to participate in the bearing and promote the bolt to increase the resistance in a timely manner to limit the deformation of rock mass. Through the close link between shallow soft rock mass and deep stable rock mass, the deformation of the shallow rock mass is well controlled and so are the development and expansion of the roof separated fissures from shallow to deep. Long high-performance sustainable bolt technology for roof are proposed and carried out to control the stability of the deep roadway roof. Engineering practice indicates that deformations of roof could be efficiently controlled. The maximum deformations of the roof and sidewall-to-sidewall are 17 mm and 24 mm, respectively. No obvious separation fissures are found in the anchoring range of roof. This study provides a reference for roof stability control of deep roadway under similar conditions.
13
Xiang, Zhe, Nong Zhang, Zhengzheng Xie, Feng Guo, and Chenghao Zhang. "Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study." Applied Sciences 11, no. 9 (April 30, 2021): 4125. http://dx.doi.org/10.3390/app11094125.
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The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.
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Krukovskyi, Oleksandr, Viktoriia Krukovska, Yurii Vynohradov, and Vladimir Dyomin. "Application of roof bolting to reduce water inflow into mine workings during the crossing of tectonic faults." E3S Web of Conferences 280 (2021): 01006. http://dx.doi.org/10.1051/e3sconf/202128001006.
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In this work, the problem of water inflow reduction in Ukrainian coal mines, which are distinguished by difficult hydrogeological conditions, was considered. A numerical study of the change in water inflow into a mine working when it crosses a tectonic fault was carried out. The cases when the permanent working was supported by frame supports and roof bolts were considered. The calculation of stress fields, zones with inelastic deformations and coefficients of permeability, which depend on the stress state and takes into account tectonic and natural permeability of the rocks, was performed. The results of calculating the water pressure and water inflow into the mine working in all considered cases are presented in the article. Analysis of the calculated data showed that a disturbed area, which covered water-bearing ricks, was formed in the roof of the mine working with the frame support. Within this area, water can move towards the contour of the mine working. The filtration permeability of the host rocks increases significantly when the mine face approaches the tectonic disturbance. The flow rate of water reaches critical values. The use of roof bolting restrains the unloading of the boundary rocks from the rock pressure and keeps them in a triaxially compressed stress state. The permeability value decreases by the value of its technological component. In different areas of the intersection of tectonic disturbance, the water inflow into the mine working with roof bolting is 3-8 times less than in the working, supported by frame supports. Therefore, the use of roof bolting allows not only to keep the mine working in a stable state, but also to significantly reduce water inflows at complicated hydrogeological conditions.
15
Su, Ming, and Xiaohui Gao. "Research of the Surrounding Rock Deformation Control Technology in Roadway under Multiple Excavations and Mining." Shock and Vibration 2021 (March 3, 2021): 1–14. http://dx.doi.org/10.1155/2021/6681184.
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To effectively control the large surrounding rock deformation of the mining roadway under multiple excavations and mining in Wangcun coal mine, the field investigation, numerical simulation, field test, and monitoring were conducted, and the characteristics of stress and deformation evolution of the surrounding rock under the influence of multiple excavations and mining were analyzed; then the collaborative supporting technology of high prestressed bolt and short anchor cables was proposed in this study. The results show the following: (1) under the influence of multiple excavations and mining, the peak vertical stress of the typical air-return roadway reaches 23 MPa, and the deformation increases by about 2.8 times after the mining of adjacent panel. (2) The principle of the roadway support under the influence of multiple excavations and mining in Wangcun coal mine is determined; from the perspective of prestress, we can conclude that the active support of short anchor cables is better than that of long anchor cables. (3) Based on the results of the field monitoring, the bolt stress can be divided into four stages: the loss stage of prestress, the sudden-decrease stage of the roof periodic weighting, the decrease stage of advanced support, and the rapid-increase stage of strong disturbance. Due to the large anchorage range of anchor cables, there is no decrease stage of advanced support. After the application of prestress, the bolt stress of side bolts and top bolts decreases, and the reduction amplitude is up to 30 kN. (4) As the panel advances, the deformation of the surrounding roadway increases, and the growth rate is also increasing gradually. However, the final displacement of the roof, floor, and two sides is within 18 mm. The bolt and anchor cables are not broken, and the control effect is good. The research results have a certain reference value for similar roadway control.
16
Ding, Xiao, and Shuan-Cheng Gu. "Analysis of the Mechanical Characteristics of Bolts under Roof Separation Based on Exponential Function." Mathematical Problems in Engineering 2020 (August 3, 2020): 1–8. http://dx.doi.org/10.1155/2020/7929157.
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With regard to the excavation of coal mine tunnels, the phenomenon of roof separation frequently occurs owing to the deformation of roadway surrounding rocks, and the analysis of the influence of surrounding rock separation on bolt reinforcement plays an indispensable role in the security of support engineering. In the present paper, the hyperbolic function model of bolt load transfer is simplified to the exponential function form, and the simplified distribution form is modified by error analysis. Drawing on the analytic model of elastoplastic mechanics of bolt load through separation, this paper further investigates the influence of separation development on bolt load and conducts the parametric analysis of the separation value and separation position. Finally, taking the separation effect into consideration in the anchorage design of coal mine, practical reference value has been attached to the supporting design of underground engineering in bedded rock mass.
17
Li, Ke, Weijian Yu, Youlin Xu, Ze Zhou, Mengtang Xu, and Wei Liang. "Analysis on the Influence Degree of Deformation Control Factors of Deep-Buried Roadway’s Fractured Surrounding Rock Using Orthogonal Design." Advances in Civil Engineering 2021 (June 7, 2021): 1–11. http://dx.doi.org/10.1155/2021/9981539.
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It is a complex issue to select the support structure parameters for a deep-buried roadway with fractured surrounding rock; especially when the support structure parameters need to be adjusted, the influence degree of support structure parameters on roadway deformation needs to be determined. The deformation of deep-buried roadway’s fractured surrounding rock development was investigated using multi-index orthoplan in this paper. According to the coal mine field investigation, support structure’s failure often occurs, and some need to be repaired many times. Through the roadway surrounding rock drilling, it was found that the stress of the surrounding rock was relieved, resulting in the cavity and separation of the stratum layer. The two sidewalls’ development and roof fractures are mainly tangential, and the original rock state appears only beyond 6.3∼8.2 m. The length of bolts, the row distance between bolts, the length of cables, and the row distance of U-shaped steel were selected as control factors in the multi-index orthogonal design, and roadway’s deformation values were taken as the test indexes. According to the orthoplan, nine numerical simulation schemes were designed, and FLAC3D was used for establishment. The range analysis method was used to analyze the test results. The results show that the control factors’ influence order on the total deformation of the roadway is as follows: row spacing between U-shaped steel > bolt length > cable length > row spacing between bolts, the influence order on the deformation of the roadway floor is as follows: row spacing between U-shaped steel > row spacing between bolts > bolt length > cable length, same as the left sidewall and right sidewall, and the influence order on the roadway roof’s deformation is as follows: row spacing between U-shaped steel > bolt length = cable length > row spacing between bolts, which provide a reference for the support design of deep-buried roadways with fractured surrounding rock, especially the adjustment of the supporting structure.
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Tian, Chen, Anhu Wang, Yingjie Liu, and Tinggui Jia. "Study on the Migration Law of Overlying Strata of Gob-Side Entry Retaining Formed by Roof Cutting and Pressure Releasing in the Shallow Seam." Shock and Vibration 2020 (December 17, 2020): 1–14. http://dx.doi.org/10.1155/2020/8821160.
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A mechanical model of a hard roof was built to analyze the pressure relief roof cutting (RCPR) process for gob-side entry retaining (GER) and identify the critical stage of roadway stability control during RCPR. Based on the mechanical analysis of key parameters of automatic roadway with RCPR, the FLAC3D software was adopted to conduct a numerical simulation to investigate the influence law of height and angle of RCPR, to analyze the trend of variations in the vertical displacement of roadway surrounding rock stress and the roof under different conditions, and to verify that the optimal roof cutting height and seam cutting angle of the 12201 working face of Halagou Coal mine are 6 m and 20°, respectively. The effect of automatic roadway with RCPR has been well implemented through conducting the bidirectional cumulative blasting test on site. To impose effective roadway surrounding rock controlling measures on Halagou Coal mine in RCPR of hard, coal-bearing roof structures at a shallow mining depth, constant resistance large deformation anchor cables, in combination with a single hydraulic prop, joist steel 11#, and steel mesh reinforcement, could provide active surrounding rock support. In addition to the active support, surrounding rock control could be strengthened using grouting bolts. Based on the result, the stress in the roadway coal side and the vertical displacement of the roof can be reduced through increasing the roof cutting height, contributing to the stability of the roadway. Increasing of the roof cutting angle will lead to the increasing of stress in the coal side of the roadway and the increasing of roof displacement with a maximum angle of 20°. Meanwhile, the peak of stress concentrating on both sides of the extreme angle is decreased. Thus, increasing the cutting roof angle at random can be unfavorable to the management of roadway roof. To develop RCPR GER, roadway surrounding rock requires greater support when the mine face passes through a cutting slot. After industrial trials, these measures are proved to be effective in controlling surrounding rock movement and developing GER.
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Wu, Peng, Liang Chen, Ming Li, Lan Wang, Xufeng Wang, and Wei Zhang. "Surrounding Rock Stability Control Technology of Roadway in Large Inclination Seam with Weak Structural Plane in Roof." Minerals 11, no. 8 (August 15, 2021): 881. http://dx.doi.org/10.3390/min11080881.
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The surrounding rock control technology of mining roadways in large inclination seams with a weak structural plane in the roof is one of the most challenging fields in underground roadway support. In view of the serious deformation of the surrounding rock of the transportation roadway in the 1201 working face of a mine, the deformation and failure characteristics and instability mechanism of the surrounding rock of the roadway are analysed. The self-stability mechanical model of the roof block structure of the roadway with a large inclination under the support effect is established, and the support concept of “high pre-stressed asymmetric” and the combined support method of bolts, wire mesh, and cables are proposed. The rationality of the supporting scheme is verified by numerical simulation. The results show that: compared with bolt and wire mesh support, the maximum shear displacement of the roof’s weak layer under the combined support of bolt, wire meshes, and cable before and after mining is reduced by 86.78% and 83%, respectively, and the maximum total displacement of surrounding rock surface is reduced by 49.22% and 37.1%, respectively. The field monitoring results show that the combined support scheme can effectively control the deformation of the surrounding rock.
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Singh, Sarvesh Kumar, Bikram Pratap Banerjee, and Simit Raval. "Three-Dimensional Unique-Identifier-Based Automated Georeferencing and Coregistration of Point Clouds in Underground Mines." Remote Sensing 13, no. 16 (August 9, 2021): 3145. http://dx.doi.org/10.3390/rs13163145.
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Spatially referenced and geometrically accurate laser scans are essential for mapping and monitoring applications in underground mines to ensure safe and smooth operation. However, obtaining an absolute 3D map in an underground mine environment is challenging using laser scanning due to the unavailability of global navigation satellite system (GNSS) signals. Consequently, applications that require georeferenced point cloud or coregistered multitemporal point clouds such as detecting changes, monitoring deformations, tracking mine logistics, measuring roadway convergence rate and evaluating construction performance become challenging. Current mapping practices largely include a manual selection of discernable reference points in laser scans for georeferencing and coregistration which is often time-consuming, arduous and error-prone. Moreover, challenges in obtaining a sensor positioning framework, the presence of structurally symmetric layouts and highly repetitive features (such as roof bolts) makes the multitemporal scans difficult to georeference and coregister. This study aims at overcoming these practical challenges through development of three-dimensional unique identifiers (3DUIDs) and a 3D registration (3DReG) workflow. Field testing of the developed approach in an underground coal mine has been found effective with an accuracy of 1.76 m in georeferencing and 0.16 m in coregistration for a scan length of 850 m. Additionally, automatic extraction of mine roadway profile has been demonstrated using 3DUID which is often a compliant and operational requirement for mitigating roadway related hazards that includes roadway convergence rate, roof/rock falls, floor heaves and vehicle clearance for collision avoidance. Potential applications of 3DUID include roadway profile extraction, guided automation, sensor calibration, reference targets for a routine survey and deformation monitoring.
21
Zhao, Zenghui, Qing Ma, Yunliang Tan, and Xiaojie Gao. "Load transfer mechanism and reinforcement effect of segmentally yieldable anchorage in weakly consolidated soft rock." SIMULATION 95, no. 1 (May 14, 2018): 83–96. http://dx.doi.org/10.1177/0037549718770284.
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Mine disasters, such as large deformation, floor heave, and roof fall, occur extremely easily in weakly consolidated soft rock strata in western China, posing enormous challenges to traditional anchorage support design. To avoid tensile failure of bolts as a result of the superposition effect of stress accumulation, a segmentally yieldable anchorage support, taking into consideration the different failure zones in surrounding rock, is presented in this paper. First, load transfer mechanisms and the process of anchorage failure are analyzed for end anchorage, full-length anchorage, and segmentally yieldable anchorage based on numerical pull-out tests. Results show that the load transfer follows a multipeak chain-like trend in the case of multipoint segmental anchorage, and that the peaks of stress attenuate slowly. Therefore, the proposed anchorage type can leverage the shear strength effectively. Furthermore, numerical models for the applications of the aforementioned three different anchoring modes to weakly consolidated soft strata are established. Results indicate that segmentally yieldable anchorage can withstand larger tensile deformation and surrounding rock deformation. Moreover, the bolt shows higher strength reservation. A combination of these characteristics is conducive to controlling deformation and damage during roadway excavation.
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Peng, Wen-qing, Wei-jun Wang, and Chao Yuan. "Supporting Technology Research in Deep Well Based on Modified Terzaghi Formula." Advances in Civil Engineering 2018 (November 13, 2018): 1–6. http://dx.doi.org/10.1155/2018/9483538.
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In order to solve the difficult problem of supporting roadway with large cross section and broken surrounding rock, the large-section inclined shaft of Pingdingshan Coal Mine is taken as the research instance. In this paper, a modified formula for the Terzaghi ultimate bearing capacity of a foundation is established based on rock mass strength criteria. As per the engineering practice, the maximum roof pressure of the inclined shaft is calculated to be 2.7 MPa, and the minimum pressure value from the modified formula is only 0.3 MPa. In order to control the floor heave of the roadway, a U-type steel inverted arch and bolts support scheme was designed. After calculating through the mechanical model of the inverted arch, its bearing capacity is 0.56 Mpa. Through comparison and analysis of various supporting schemes, finally, the “U-type steel + inverted arch + pouring concrete + backwall grouting” technology is selected, and the engineering practice shows that the supporting scheme can effectively improve surrounding rock stability.
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Paul, Avinash, A. P. Singh, John Loui P, Ajoy K. Singh, and Manoj Khandelwal. "Validation of RMR-based support design using roof bolts by numerical modeling for underground coal mine of Monnet Ispat, Raigarh, India—a case study." Arabian Journal of Geosciences 5, no. 6 (March 23, 2011): 1435–48. http://dx.doi.org/10.1007/s12517-011-0313-8.
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Wang, Kai, Lianguo Wang, and Bo Ren. "Failure Mechanism Analysis and Support Technology for Roadway Tunnel in Fault Fracture Zone: A Case Study." Energies 14, no. 13 (June 23, 2021): 3767. http://dx.doi.org/10.3390/en14133767.
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This paper introduces a case study on the failure mechanism and support design of a roadway tunnel in the fault fracture zone of the 106 mining area in the Yuandian no.2 coal mine. Based on the on-site geological conditions (in-situ stress test, borehole television imaging, and lithological analysis), the failure mechanism of the roadway tunnel in the fault fracture zone was studied. The test results showed that the high tectonic stress, fractured rock, and poor lithology are the primary reasons for the roadway instability. According to the support principles of grouting reinforcement, pre-reinforced support, and rational support range, a new type of combined support technology was proposed, including advanced grouting, grouting bolts, and grouting anchor cables. A 100 m roadway section was selected for field testing using the new support scheme, and detailed deformation monitoring was performed. Monitoring results showed that the roadway deformation under the new support was significantly reduced. During the roadway excavation process, no roof collapse phenomenon occurred, and the safety of roadway excavation was ensured. This successful case provides an important reference for similar roadway projects in the fault fracture zone.
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Zerradi, Y., A. Lahmili, and M. Souissi. "Stability of a rock mass using the key block theory: a case study." E3S Web of Conferences 150 (2020): 03024. http://dx.doi.org/10.1051/e3sconf/202015003024.
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In underground mines, excavating disturb the initial equilibrium state of the rock mass, and therefore require selection of a support in order to control the movement of rocks, avoid landslide and work safely. Thus, the progress of mining operations in the ST2 mineralization, in the eastern zone of the Bouazzer mine, is disrupted because of stability problems. On the basis of field observations and analyzes of core drill, the geological and structural study, carried out in this area, has shown the existence of three types of facies: altered and cracked diorite, cobaltiferous mineralization which is in contact with serpentinites. In fact, the empirical methods such as Barton, Bieniawski and the recommendations of the AFTES have qualified the rock mass as poor, furthermore they proposed as kind of supports: steel arches, shotcrete and rock-bolts. Numerical simulation by the finite element method proved to be very complex due to existence of several types of discontinuities (faults, shistosities and joints).These discontinuities are natural fractures that delimit various shapes and sizes of wedges, which can become detached from the roof or siding of the excavation and collapse under their own weight. Although the empirical methods cited above provide supports for each facies, however, this support is expensive and difficult to implement in practice because it must cover the entire surface of the excavation and thus not allowing to detect stable blocks that do not require a support. For this it was essential to carry out an analysis of wedges to better locate unstable blocks. The treatment of fracturing data has highlighted the presence of five sets of discontinuities of which three sets are principals and the other two are minor joints. Then, while taking into account the geometrical, mechanical data of the discontinuities as well as the geometrical data of the excavation, we were able to detect the shape and the size of the unstable blocks and the sets of discontinuities delimiting them and which favor their sliding and tilting. Thus, we calculated the number of anchor bolts needed to stabilize these blocks in order to ensure an acceptable safety factor. This study shows clearly how a wedge analysis of the rock mass can guide and optimize the support work.
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Chen, Zhiyu, Zhiqiang Yin, Jucai Chang, Wenbao Shi, and Xingqiu Peng. "Failure Characteristics and Stability Control of Roadway Surrounding Rocks under Different Lateral Pressure Coefficients." Journal of Engineering Science and Technology Review 13, no. 5 (2020): 42–49. http://dx.doi.org/10.25103/jestr.135.06.
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The stability control of mining roadways is crucial in ensuring the safe and efficient mining of deep coal resources. Given the effect of mining stress on the working face, the support scheme of such roadways, which is designed based on the original in-situ stress parameters, often presents support-related problems. A mining roadway on the 1131 working face of Zhujidong Coal Mine in the Huainan mining area, China was taken as the engineering background of this study. To explore the influence of mining stress on the stability control of this roadway, the 2-dimensional (2D) Particle Flow Code (PFC) numerical simulation software was used to perform a simulation study on the stress distribution characteristics and deformation failure laws of the surrounding rocks under the change in the roadway lateral pressure coefficient caused by the mining stress. An improved support scheme that considers the influence of varying lateral pressure coefficient on the mining roadway was then proposed. Results show that when the lateral pressure coefficient increased from 1 to 1.4, the maximum principal stress (61.2 MPa) is observed at 2.9 m inside the roof of the surrounding rocks in the roadway. When the lateral pressure coefficient decreases from 1 to 0.4, the maximum principal stress (46.2 MPa) is observed at 2.2 m inside the surrounding rock of sidewalls of the roadway, and failure occurs. These findings suggest that the deformation and failure of surrounding rocks are affected regardless of the lateral pressure coefficient increase or decrease. On this basis, the lengths of the anchor bolts in the roof and sidewalls in the original support method are increased from 2,200 mm to 3,000 mm and 2,500 mm, respectively. The field monitoring results indicate that the improved support method mitigates the deformation and realizes the stability control of the roadway surrounding rocks. The findings of this study could provide a scientific basis for the parameter design of roadway support.
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Skrzypkowski, Krzysztof. "Laboratory testing of a long expansion rock bolt support for energy-absorbing applications." E3S Web of Conferences 29 (2018): 00004. http://dx.doi.org/10.1051/e3sconf/20182900004.
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The main purpose of rock support and reinforcement in underground mining is to maintain excavations safe and open for their intended lifespan. The basic type of rock mass reinforcement method both in ore and hard coal mining is rock bolt support. Very often, existing bolt support systems are not always capable of providing a reliable controlled performance. Therefore, in recent years energy-absorbing bolts which are exposed to dynamic loading, for example from rock burst caused by high rock stresses, earthquakes, or blasting have appeared. In this article particular attention was paid to short and long expansion bolts. Quasi-static tests of expansion bolts were carried out at the laboratory test facility in simulated mining conditions, especially for the KGHM Polska Miedź S.A. mines. In the underground mines of the Legnica-Głogów Copper District (LGOM) the main way to protect the room excavation is rock bolt support with a length from 1.2 m to 2.6 m. Rock bolt support longer than 2.6 m is considered as additional support of excavations and is increasingly being used to reinforce the roofs. The comparisons of energy-absorbing short and long expansion bolts with a length of 1.8m, 3.6m and 5.2m were presented. In addition, for elastic and plastic range of each bolts were determined.
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Skrzypkowski, Krzysztof, Waldemar Korzeniowski, Krzysztof Zagórski, and Anna Zagórska. "Modified Rock Bolt Support for Mining Method with Controlled Roof Bending." Energies 13, no. 8 (April 11, 2020): 1868. http://dx.doi.org/10.3390/en13081868.
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The article presents methods of making the rock bolt support more yieldable, especially for a stratified roof. Alongside the increasing depth of exploitation of raw material deposits, rock bolt support units are more often designed taking into account more intensive deformations and displacements of underground excavations. In the article, a room and pillar method with mined roof bending and roof reinforcement with bolt patterns of 1 m × 1 m, 1.5 m × 1.5 m and 2 m × 2 m is presented. Moreover, the laboratory tests included 1.8 m long bolts, which were embedded segmentally on the lengths of 100 mm, 150 mm and 200 mm were tested. Based on the load–displacement characteristics, the deformation energy for flat and profiled dome bearing plates was calculated. Making the segmentally embedded resin rock bolt support yieldable enabled it to perform additional work. Furthermore, it was found that rock bolt support with a dome bearing plate took over 2.5 times more energy compared to a rock bolt support equipped with a flat bearing plate.
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Kwaśniewski, Janusz, Ireneusz Dominik, Krzysztof Lalik, Waldemar Korzeniowski, Krzysztof Zagórski, and Krzysztof Skrzypkowski. "Rock Bolts Health Monitoring Using Self-Excited Phenomenon." Solid State Phenomena 248 (March 2016): 186–91. http://dx.doi.org/10.4028/www.scientific.net/ssp.248.186.
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Health monitoring of rock bolts can indirectly indicate the state of rock which is crucial for mining safety. This paper presents an innovative application of the Self-excited Acoustical System SAS for stress change measurement in rock bolts which are used to secure roofs and walls in mines and tunnels. The method gives information on the change of rock stress in the immediate area next to the bolt. It can be used also to determine the necessity of the exploited bolt replacement.
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Xiang, Zhe, Nong Zhang, Deyu Qian, Zhengzheng Xie, Chenghao Zhang, Feng Guo, and Sujian Wang. "Failure Characteristics and Stability Control of Bolt Support in Thick-Coal-Seam Roadway of Three Typical Coal Mines in China." Shock and Vibration 2021 (August 6, 2021): 1–16. http://dx.doi.org/10.1155/2021/5589085.
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Roadways in thick coal seams are widely distributed in China. However, due to the relatively developed cracks and brittleness of coal, the support failure of thick-coal-seam roadways frequently occurs. Therefore, the study of bolt failure characteristics and new anchoring technology is very important for the safety control of thick-coal-seam roadways. Based on field observations, the failure mechanism of selected roadway failures under distinct conditions at three representative coal mines in eastern and western China was analyzed. Recommendations are provided for roadway safety control. The results show that the strength and dimension of the anchoring structure in the coal roof of thick-coal-seam roadways are the decisive factors for the resistance of the roadway convergence and stress disturbance. The thick anchoring structure in the roof constructed by flexible long bolts can effectively solve the problem of support failure caused by insufficient support length of traditional rebar bolts under the condition of extra-thick coal roof and thick coal roof with weak interlayers. The concepts and techniques presented in the paper provide a reference for the design of roadway support under similar geological conditions and dynamic load.
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Dvořák, Pavel, and Eva Jiránková. "EFFECTS ON THE FINAL INTENSITY OF INPUT FORCES IN LONGBOLTS INSTALLED AT THE MINING OPERATION 2 AREA, OKD, INC." Acta Polytechnica 58, no. 5 (October 31, 2018): 279. http://dx.doi.org/10.14311/ap.2018.58.0279.
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In the deep coal mines of OKD, Inc., both bolts and long bolts of different designs are used for the rock massif and steel arch support reinforcement. Continuous measurement of forces in 6 strand bolts and 1 cable bolt (long bolts, generally) was carried out during the trial operation of the modified Room and pillar mining method at Mining operation 2, site North, OKD, Inc. Hydraulic dynamometers were installed on these long bolts and a monitoring of forces took place throughout the life-time period of the mining panel No. V. From this measurement, a knowledge of their different load behavior with respect to the input stress parameters was obtained. The input intensity of the force applied to the bolting elements is burdened by losses of various kinds. The subject of the article is a description and analysis of the intensity of the initial stressing force applied to individual long bolts (with a threaded clamping bush or wedge barrel) and quantization of short-term stress losses with a description and analysis of these.
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Rong, Hai, Liting Pan, Xiaoyan Li, Ming Wang, Zeliang Qu, Mengsheng Lu, and Kaipeng Guo. "Analysis on Influence Factors of Roadway Instability in High-Stress, Steeply Inclined Extra-Thick Coal Seam." Advances in Civil Engineering 2021 (September 13, 2021): 1–17. http://dx.doi.org/10.1155/2021/4676685.
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In order to solve the problem of roadway support safety in coal mining under high stress conditions and to improve safe and efficient production in coal mines, the control countermeasures of the surrounding rock stability and the optimization scheme of support are put forward and the model and numerical simulation of roadway bolt support system are established. Based on bolt support theory and instability mechanism of the coal rock dynamic system, this paper puts forward the evaluation of support effect and the optimization parameters of bolt support, and the scheme of mine pressure monitoring and the corresponding support optimization system are established. The roof fall accident and the bolt and cable of support have been broken in the Wudong coal mine, the phenomenon of bolt pulling out in the roadway. The causes of roof fall are analyzed and the solutions are put forth, judging the influence of different factors on roadway support. In view of the roof fall accident in the North Lane of the east wing of the +575 level 43 #coal seam in the north mining area of the Wudong coal mine, the cause analysis and support suggestions are made. And, according to the performance of the bolting material and anchoring agent, the laboratory theoretical research was carried out. Through the experiment, it is concluded that the FRP bolt with a diameter not less than 27 mm is the first choice for the side support of the working face in the mining roadway, then ribbed steel bolt with a diameter not less than 20 mm for the nonworking face, and the length of the anchor rod not less than the range of the loose circle. Therefore, full-length anchoring should be carried out in roadway support, the anchorage length of the anchor cable should be increased, and the integrity of the roof should be improved, so as to reduce the amount of roadway roof separation and improve the support effect.
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Zhang, Mei Chang, Peng Cheng Fei, and De Long Zou. "Numerical Simulation Analysis of the Nanyangpo Coal Mine Anchor Support Method." Advanced Materials Research 619 (December 2012): 231–38. http://dx.doi.org/10.4028/www.scientific.net/amr.619.231.
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The bolt support is important to ensure the stability of surrounding rock. Of Nan Yangpo mines as the research background. The application of numerical simulation software FLAC3D mine deep Bolt bolt support after the surrounding rock deformation law of the numerical simulation, Comparison and analysis of rock displacement and plastic zone under the support program changes. The results show that, The third bolt support nursing program, Significantly improve the strength and load carrying capacity of the surrounding rock, Effectively control the damage of the deep tunnel deformation that can control the roof of 4101 the return airway and two to help the stability.
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Skrzypkowski, Krzysztof, Waldemar Korzeniowski, Krzysztof Zagórski, and Piotr Dudek. "Application of Long Expansion Rock Bolt Support in the Underground Mines of Legnica–Głogów Copper District." Studia Geotechnica et Mechanica 39, no. 3 (September 1, 2017): 47–57. http://dx.doi.org/10.1515/sgem-2017-0029.
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Abstract In the underground mines of the Legnica–Głogów Copper District (LGOM) the main way to protect the room excavation is the use of a rock bolt support. For many years, it has proven to be an efficient security measure in excavations which met all safety standards and requirements. The article presents the consumption of the rock bolt support in the Mining Department “Polkowice–Sieroszowice” in the years 2010–2015 as well as the number of bolt supports that were used to secure the excavations. In addition, it shows the percentage of bolt supports that were used to conduct rebuilding work and cover the surface of exposed roofs. One of the factors contributing to the loss of the functionality of bolt supports is corrosion whose occurrence may lead directly to a reduction in the diameter of rock bolt support parts, in particular rods, bearing plates and nuts. The phenomenon of the corrosion of the bolt support and its elements in underground mining is an extremely common phenomenon due to the favorable conditions for its development in mines, namely high temperature and humidity, as well as the presence of highly aggressive water. This involves primarily a decrease in the capacity of bolt support construction, which entails the need for its strengthening, and often the need to perform the reconstruction of the excavation. The article presents an alternative for steel bearing plates, namely plates made using the spatial 3D printing technology. Prototype bearing plates were printed on a 3D printer Formiga P100 using the “Precymit” material. The used printing technology was SLS (Selective Laser Sintering), which is one of the most widely used technologies among all the methods of 3D printing for the short series production of the technical parts of the final product. The article presents the stress–strain characteristic of the long expansion connected rock bolt support OB25 with a length of 3.65 m. A rock bolt support longer than 2.6 m is an additional bolt support in excavations, and it is increasingly frequently used to reinforce roofs and in rebuilding the underground mines of KGHM Polish Copper S.A. In order to conduct the laboratory tests that are most suitable for the mine conditions, and yet are carried out on a laboratory test facility, the Authors used a steel cylinder with an external diameter of 102 mm and a length of 600 mm, which was filled with a core of rock (dolomite) from the roofs of the mine workings. In addition the maximum load that took over the bolt support made of rods and connected with sleeves was determined. For the initial tension, the elastic and plastic range of the maximal displacements, which were measured by the rope encoder, were determined. The statical tests of the expansion rock bolt support were carried out at the laboratory of the Department of Underground Mining in simulated mine conditions. The test facility enables the study of the long bolt rods on a geometric scale of 1:1 for the different ways of fixing. The aim of the laboratory research was to obtain the stress–strain characteristics, of the long expansion rock bolt support with a steel bearing plate and a plate printed on a 3D printer.
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Zhang, Nong, Yi Ming Zhao, and Guang Yao Si. "Rock Bearing Capacity-Based Stepwise Bolting for Deep Underground Coal Roadway in China." Advanced Materials Research 255-260 (May 2011): 3812–16. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.3812.
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Complicated occurrence situation of deep underground coal seams in China determines absence of a national rock classification index. Take Huainan mining area as an example, this paper aims to provide a practical method. It begins with a geo-mechanical assessment to check bolting feasibility of related rock mass. Once this is settled, roof self-bearing capacity coefficient and coal hardness coefficient which can comprehensively indicate basic characteristics of surrounding rock are integrated to classify the surrounding rock into four levels. Accordingly, stepwise bolting are provided according to dynamic combination of four basic bolting forms: super bolt assembly, cable bolt beam, high-pretension roof truss and metal chock plus grouting. An application case with rock Level III in Guqiao Mine, Huainan was introduced. Statistics show that bolt-based supporting is widely being used in more than 80% of Chinese coal mines with sound efficiency and applicability.
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Skrzypkowski, Korzeniowski, Zagórski, and Zagórska. "Flexibility and Load-Bearing Capacity of Roof Bolting as Functions of Mounting Depth and Hole Diameter." Energies 12, no. 19 (September 30, 2019): 3754. http://dx.doi.org/10.3390/en12193754.
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This paper presents the results of laboratory tensile testing of segmentally-installed glue-in roof bolting. We studied roof bolting of the type Olkusz-16A (Boltech Sp. z o.o., ZGH Bolesław S.A., Bukowno, Poland), additionally equipped with a steel rod coil, which was mounted in steel cylinders filled with a concrete mixture using multi-part resin cartridges with a diameter of 0.024 m and length of 0.045 m. The mounting depths were 0.1 m and 0.2 m, respectively. Our main purpose was to determine the effect of the bolt hole diameter, which assumed the values 0.028 m, 0.032 m, 0.035 m, and 0.037 m, respectively, on the load-bearing capacity of the roof bolting in relation to the mounting depth. We found that the mounting depth of 0.2 m was sufficient for the roof bolting to exhibit its full load and displacement properties for all four diameters of the bolt hole. To determine whether the roof bolting was capable of transferring the load in situ, we presented the results of the predicted load on the roof bolting applied in a room and pillar mining method in an underground mine of zinc and lead ore deposits. Our objective was to determine the influence of the room and pillar mining method geometry on the range of the fault zone of rocks around pits. We designed the deposit excavation model using the Examine3D numerical modeling software, which is based on the boundary element method. We created three-dimensional models for three variants of working space opening widths: featuring two, three, and four rows of rooms. The geometry of rooms and pillars corresponded to the mine conditions; the width, height, and length parameters were all 5 m. We determined the strength, strain, and structural parameters of the rock mass on the basis of laboratory studies of the drill core and rock forms collected from the room longwall. We used the strength factor to specify the maximum range of the fault zone of rocks around pits. In the last stage of research, we compared the load value obtained based on numerical testing with the maximum load obtained in the tensile strength tests of the roof bolting and determined the safety factor of the segmentally-installed roof bolting.
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Guo, Dong Ming, Jing Zhao Zhuang, Yi Zhang, Yan Bin Wang, and Ren Shu Yang. "Design and Field Test of Bolt-Mesh-Cable Support of Extraction Drift in Soft Thick Seam with a Large Angle." Advanced Materials Research 243-249 (May 2011): 3565–71. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3565.
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Considering the poor support results of extraction drift in soft thick seam with a large angle in Dujiacun Mine, and there’s no similar design in such engineering geological conditions. Firstly, determined surrounding rock stability classification of the drift and obtained that roadway surrounding rock of this mine is type. According to the approximate range of this type roadway surrounding rock, selected parameters of bolt support, then using FLAC3Dsoftware simulated support effect of the roadway with different parameters of bolt support, analyzed the extent of the support effect of various parameters. The simulation results show that the optimal program is φ2200mm round steel bolt in the roof andφ2500mm equal strength thread steel in the two sides. Monitoring results of ground pressure displacement of surface, load of bolt and amount of roof separation show that bolt-mesh-cable support is safe and effective.
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Layer, E. "Automatic roof bolt strain monitoring in coal mines." International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 33, no. 1 (January 1996): 93–95. http://dx.doi.org/10.1016/0148-9062(95)00044-5.
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Feng, Xiaowei. "Supporting problems at an island mining face in Shanxi, China. Case study based on field observation." New Trends in Production Engineering 2, no. 1 (October 1, 2019): 257–67. http://dx.doi.org/10.2478/ntpe-2019-0027.
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Abstract In this paper, field observation is conducted in Fujiaao Coal Mine, Linfen city in Shanxi province, China, which is unique because of its island-typed mining layout. Firstly, geology, layout of the coal cutting face, supporting pattern are presented and details are also provided. Then the problems are discussed and analyzed based on existing bolting theories. It finds out the length of the cable bolt is too long, which requires long time to drill boreholes, whilst the effectiveness is limited due to the illogical combination between cable bolt function zone and rock bolt function zone. Also, the face place allocated to rock bolt is very likely to cause line contact between its edge and steel belt, thus the bearing force is tremendously weakened and solely determined by strength of belt. Furthermore, field observation proves the low active supporting effects to roof, thus leading obvious roof sink even without the disturbance of mining activity. Eventually, some solutions are proposed with the intention to improve the situation based on the economic and technical considerations, including bolting in humidity environment, rational cable bolt length, wise choice of face plate, and ways to increase pretension force. The viewpoints and comments of this study can be referred by practitioners in coal mines sharing same difficulties.
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Liu, Guang-jian, Shan-lin Li, Zong-long Mu, Wen Chen, Lei-bo Song, Jie Liu, and Yu-dong Xu. "Numerical Study on the Impact Instability Characteristics Induced by Mine Earthquake and the Support Scheme of Roadway." Shock and Vibration 2021 (September 11, 2021): 1–16. http://dx.doi.org/10.1155/2021/7697905.
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Rockburst of deep roadway was induced by the superposition of mine earthquake disturbance and high static stress exceeding the limit strength of coal-rock mass. To study the roadway impact instability characteristics caused by mine earthquake disturbance and to propose an optimized support scheme, the discrete element model of the roadway structure was established based on the 1305 working face of the Zhaolou Coal Mine. The influence of mine earthquake amplitude and hypocenter location on the roadway was analyzed. The mesocrack evolution characteristics of the roadway were simulated and reproduced. Characteristics of stress field, crack field, displacement field, and energy field of the disturbed roadway with different support schemes were studied. The results showed that the greater the amplitude of the mine earthquake was, the severer the roadway impact failure was. The upper and left hypocenters had a significant influence on the roadway. The superposition of the high static stress and the dynamic stress due to the far-field mine earthquake resulted in the impact instability of coal-rock mass around the roadway, causing severe roof subsidence as well as rib and bottom heave. The evolution of tensile cracks caused the severe impact failure of roadway from a mesoscopic perspective. Using the flexible support to reinforce the roadway retarded the stress decline in roof and rib, improved the self-stability, reduced the number of near-field cracks, and decreased the displacement. Meanwhile, it allowed the roof and rib deformation, which was conducive to releasing elastic energy in surrounding rocks and reducing mine earthquake energy. The cracks and deformation in the floor were controlled by using the floor bolt. The optimal support scheme for a roadway to resist mine earthquake disturbance was proposed: “bolt-cable-mesh-steel strip-π-beam + floor bolt.” The research results have a specific guiding significance for the support of the coal mine roadway.
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Skrzypkowski, Krzysztof. "Case Studies of Rock Bolt Support Loads and Rock Mass Monitoring for the Room and Pillar Method in the Legnica-Głogów Copper District in Poland." Energies 13, no. 11 (June 10, 2020): 2998. http://dx.doi.org/10.3390/en13112998.
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The article presents the impact of geological and mining factors on the stability of room excavations in the Legnica-Głogów Copper District (LGOM) in Poland. In underground mining, the primary task of bolting of mining excavations is to ensure their stability as an essential condition of work safety. Appreciating the role and importance of the rock bolting in Polish ore mining; rock bolt load sensors were designed, manufactured and tested under laboratory conditions. The purpose of the research was to characterize the sensors and determine the elastic range of the bearing plate, which are an integral part of the sensor. The sensors have been verified in industrial conditions. The tests were carried out in the underground copper ore mine in Poland. Three rooms in the exploitation field were selected for testing, where exploitation was carried out at a depth of 809–820 m below the ground surface with the application of room and pillar with roof deflection and maintaining the central part of the field. The exploitation field included 60 rooms and pillars. The effectiveness of the mechanical load sensor of the expansion rock bolt support has been experimentally confirmed. Based on mine research, it was found that the largest increases in the load of the rock bolting, vertical stress and convergence occur in the middle of the mining field.
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Chang, Jucai, Kai He, Zhiqiang Yin, Wanfeng Li, Shihui Li, and Dongdong Pang. "Study on the Instability Characteristics and Bolt Support in Deep Mining Roadways Based on the Surrounding Rock Stability Index: Example of Pansan Coal Mine." Advances in Civil Engineering 2020 (September 10, 2020): 1–16. http://dx.doi.org/10.1155/2020/8855335.
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In view of the influence of mining stress on the stability of the surrounding rock of inclined roof mining roadways in deep mines, the surrounding rock stability index is defined and solved based on the rock strength criterion and the stress distribution. The mining roadway of the 17102(3) working face of the Pansan Coal Mine is used as the engineering background and example. The surrounding rock’ stabilities under the conditions of no support and bolt support are analyzed according to the surrounding rock’s stability index and the deformation data. The results show that the areas of low wall and high wall instability are 1.68 m2 and 2.12 m2, respectively, and the low wall is more stable than the high wall; the areas of the roof and floor instability are 0.33 m2 and 0.35 m2, respectively, and the roof and floor are more stable than the two sides. During mining, the area of instability greatly increases at first, then decreases to 0, and reaches a maximum value at the peak of the abutment pressure. The stability of the surrounding rock decreases first and then increases. Compared with the end anchoring bolt support, the full-length anchoring bolt support reduces the area of instability to a greater extent, and the full-length anchoring bolt support effect is better. The surrounding rock in the end anchoring zone and the full-length anchoring zone began to deform significantly at 200 m and 150 m from the working face, respectively. This indicates that the control effect of the full-length anchoring bolt support is better and verifies the rationality of the surrounding rock stability index to describe the instability characteristics. This research method can provide a theoretical reference for analysis of the stability characteristics and support design of different cross-section roadways.
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Zhao, Li, Zhang, and Yang. "Stability Analyses and Cable Bolt Support Design for A Deep Large-Span Stope at the Hongtoushan Mine, China." Sustainability 11, no. 21 (November 3, 2019): 6134. http://dx.doi.org/10.3390/su11216134.
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This study presents stability analyses and a cable bolt support design for a typical deep large-span stope (1-1# stope) at the Hongtoushan mine in China, using an integrated empirical and numerical method. Detailed field work including quantification of joint distribution and surface quality, along with laboratory test on intact rock samples, were performed to obtain the geotechnical properties of rock masses. The rock mass of the 1-1# stope was characterized by rock mass rating (RMR), rock mass quality (Q), and geological strength index (GSI), and then the modulus, peak strength, cohesive strength, and internal friction angle of the rock mass were estimated. The stability of the stope was then evaluated by empirical (RMR, stability graph) and numerical approaches (limit equilibrium analyses with UNWEDGE and stress-strain analyses with FLAC3D), considering of the effects of rock mass quality, induced stress, and large-span. A cable bolt support system obtained from the empirical method, was then further analyzed using the FLAC3D and UNWEDGE codes. The results show that the maximum plastic zone thickness and vertical displacement at the stope roof decrease significantly and the safety factor of the unstable wedge block increases significantly after installing the cable bolt support systems recommended by the empirical method. Therefore, it is suggested that an integrated empirical and numerical method is used to obtain quantitative stability assessment and optimum cable bolt support design for deep large-span stope roofs.
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Chen, Lu, Chuan Wei Zang, Feng Hai Yu, and Xiang Kun Yu. "Optimization on Gateway Section of Soft Coal Seam and Hard Roof and Supporting Technology." Applied Mechanics and Materials 90-93 (September 2011): 622–25. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.622.
Full textAbstract:
Support invalidity of a roadway have a largely influence on production safety of coal mines, especially the soft coal roadway, which deforms heavily. To solve this problem, it began from the gateway section optimization, based on the actual geological condition of Chang-gouyu Mine. The computational model was established up to optimize tunnel shapes using FLAC3D. The scopes of plastic zone, stress field, displacement field were compared and analysed for different shapes of roadway. The irregular trapezoid section is adopted, then the bolt support parameters were designed and field application was done. By using the irregular trapezoid, the stress distribution around the roadway is improved and the deformation and plastic zone is decreased. Under the geological conditions of the soft coal seam and hard roof strata, the stability of roadway was effectively controlled by using optimized trapeziform cross-section and bolting support.
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Gao, Feng, Qing Guo Huang, and Gui Ling Liu. "Study on Optimal Roadway Bolt Supporting Scheme with Easy-Breaking Roof." Advanced Materials Research 524-527 (May 2012): 705–8. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.705.
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The roadway bolt supporting with easy-breaking roof is a complex systematic problem, and the success or failure of roadway bolt supporting is determined by pre-stress level in some sense. To well recognize the bolt supporting effect under different pre-stress level, the laneway which has cracky roof is taken to systematically analysis the changing situation of roadway’s stress and deformation by using 2-dimension finite difference code -FLAC2D.The theoretical analysis and practical observation results show that high pre-stress scheme is the best way to improve the roadway surrounding rock strength and to control the cracky roof roadway’s deformation. It has some references to engineering design, construction and maintenance for similar soft rock mines.
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Tang, Jian Quan, and Xian Yin Qi. "Roadway Stability and Determination of the Critical Value of Roof Abscission Layer." Applied Mechanics and Materials 446-447 (November 2013): 1466–71. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.1466.
Full textAbstract:
In condition of extraction roadway with existing bolt support at Zhao Lou coal mine as the object, the substantial function and evolution mechanism of anchor rod and anchorage structure are studied by using a variety of means; perfected suggestions about roof separation indicator are put forward; the separation phenomenon and the bolt support structure interaction state and the correlation of roadway stability are researched; method of determination of the critical value of roof separation are put forward and the criterion of the bolting structure failure and surrounding rock losing stability of roadway with the bed-separation volume as the main indicator are provides the basis for.
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Li, Ting Chun, Hui Wang, Xue Yang Xing, and Yu Qing Zhang. "Numerical Analysis and Evaluation on Supporting Parameters in Coal." Applied Mechanics and Materials 90-93 (September 2011): 290–97. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.290.
Full textAbstract:
At the turn of the last century, bolt supporting of coal roadway had rapidly developed with the applied range of bolt stretching continually. The bolt supporting in roadway has been implemented widely. But until now, there is no reliable theoretical support or appraisal system on the design of bolt supporting roadway and the evaluation of supporting conditions. Supporting effect is tested only by practice and roof-fall accidents take place repeatedly. This paper conducts the research on the bolt supporting parameters in No.315 transportation-up-hill roadway of Nan Ye Coal Mine with numerical analysis method; it is discovered that numerical analysis can be a good way to predict and evaluate roadway supporting effects to be worthy popularizing.
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Xu, Ying, Xiekang Zhou, and Weimei Gong. "Mechanism and Control of Cable Breakage in a Roadway with Thick Top Coal in a Rockburst Mine." Advances in Civil Engineering 2021 (June 12, 2021): 1–12. http://dx.doi.org/10.1155/2021/2275820.
Full textAbstract:
Because top coal is not stable, a roadway with thick top coal often appears to mine pressure problems, such as bolt failure, cable breakage, and roof caving. In particular, these problems are more serious in rockburst mines. Based on a cable breakage case of No. 3 roadway in Xingcun coal mine, the paper analyzed the stress and elastic energy evolution law of surrounding rock and stress state of cable in the 3# roadway by means of the numerical simulation method. Thus, the cable breakage mechanism of the roadway with thick top coal in rockburst mine was revealed. Then, because surrounding rock grouting can reduce the stress concentration of surrounding rock and cable, surrounding rock grouting technology was proposed as control technology of cable breakage. Finally, parameters of surrounding rock grouting were designed and applied in the No. 3 roadway. The field results showed that surrounding rock grouting technology can be one of the solutions for cable breakage of roadway with thick top coal in rockburst mine. The research results of this paper can provide certain theoretical and practical value for mine pressure control of roadway.
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Yu, Yang, Xiangyu Wang, Jianbiao Bai, Lianying Zhang, and Hongchun Xia. "Deformation Mechanism and Stability Control of Roadway Surrounding Rock with Compound Roof: Research and Applications." Energies 13, no. 6 (March 14, 2020): 1350. http://dx.doi.org/10.3390/en13061350.
Full textAbstract:
In view of problems with roadways with a compound roof, such as the occurrence of instability in the roof strata, ease of separation of the layer caving, difficulty of maintenance, and poor safety, we established a mechanical calculation model of a roadway with compound roof using the elastic mechanics theory, taking the stability control of a roadway with compound roof at a coal mine in Guizhou Province, China as the research background, and based on the actual characteristics of the coal seam and the roof and floor slate. Expressions of the separation layer and instability limit load of compound roof were derived, and the calculation and verification were carried out in combination with the actual conditions. By means of numerical simulation, the distribution and evolution laws of stress, displacement and plastic zone of roadways with a compound roof were studied, and the deformation characteristics and instability mechanism of roadways with a compound roof were revealed: (1) in early stage deformation of roadway, the amount is large, the speed is fast, and the scale is wide; (2) compound roofs are vulnerable to abscission and instability, the bearing capacity of the two sides is low due to softness and cracking, the shear failure of side angles and vertex angles weakens the strength of surrounding rock, and the self-bearing capacity of surrounding rock is low; (3) the bolt and anchor bear relatively large tensile force, and the support structure is easy to be broken up. On this basis, the stability control principle of a roadway with compound roof tunnel was put forward: fast and timely support; high-strength bolt strong support; improving the stability of the roof and the bearing capacity of the two sides; restraining the shear failure of the key bearing parts such as the side angles and the bottom angles, and targeted stability control technology for roadways with a compound roof was developed. The field industrial test showed that the deformation of this roadway with a compound roof was effectively controlled and the overall stability of the roadway was effectively improved. The results of this study could provide useful reference for a roadway with a compound roof under similar conditions.
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Stimpson, B. "Optimizing the reinforcement effect of full-column, untensioned, grouted bolts in bedded mine roofs." International Journal of Mining and Geological Engineering 5, no. 3 (October 1987): 285–98. http://dx.doi.org/10.1007/bf01560779.
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