Proceedings of the Ninth International Conference on Deep and High Stress Mining最新文献

{"title":"Addressing some misconceptions regarding seismic hazard assessment in mines","authors":"Johan Wesseloo","doi":"10.36487/ACG_REP/1952_21_WESSELOO","DOIUrl":"https://doi.org/10.36487/ACG_REP/1952_21_WESSELOO","url":null,"abstract":"Seismic hazard assessment, in some form or another, has formed part of seismic risk management in seismically active hard rock mines for decades. Whilst recent advances have been made in seismic hazard assessment, some misconceptions with respect to seismic hazard assessment appear to be present in the industry. Where these misconceptions exist, they adversely affect the quality of seismic hazard assessment and risk management decision-making. This paper address some of these misconceptions the author has encountered in the mining industry.","PeriodicalId":213743,"journal":{"name":"Proceedings of the Ninth International Conference on Deep and High Stress Mining","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129577534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In-situ stress around source faults of seismic events in and beneath South African deep gold mines","authors":"Y. Yabe, Shuhei Abe, Takatoshi Ito, A. Ishida, Kosuke Sugimura, M. Kanematsu, M. Higashi, R. Tadokoro, H. Ogasawara, A. Funato, H. Kato, B. Watson, S. Mngadi, R. Durrheim, G. Hofmann, L. Scheepers","doi":"10.36487/ACG_REP/1952_30_YABE","DOIUrl":"https://doi.org/10.36487/ACG_REP/1952_30_YABE","url":null,"abstract":"To demonstrate the possibility of stress measurement at depths of more than 3 km, in-situ stress states were determined around the source faults of three seismic events: a Mw2.2 seismic event at about 3.3 km below surface in Mponeng gold mine, a Mw3.5 seismic event at about 3.5 km below surface in the Savuka gold mine, and the Orkney earthquake (Mw5.5), with its hypocentre about 5 km below surface, beneath the Moab Khotsong gold mine. \u0000The Mw2.2 seismic event occurred in a 30 m thick gabbroic dyke that intruded into a host rock of quartzite. A 90 m long borehole was drilled to penetrate its source fault. Borehole breakout and core discing were observed in the host rock and the hanging wall of the source fault, i.e., in the dyke. Diametrical core deformation analysis (DCDA) and deformation rate analysis (DRA) were applied to core samples retrieved from the borehole. \u0000The DCDA determines the differential stress in the plane normal to a borehole by measuring the cross-section shape of a core sample, while the DRA reproduces the normal stress in the orientation in which a cyclic loading is applied, i.e., to obtain hysteresis of the stress-strain curves. By integrating these measurements and criteria of the borehole breakout and the core discing, the principal stress states in the host rock, the footwall in the dyke and the hanging wall in the dyke were reproduced. Significant differences were found between the stress states in the footwall and the hanging wall. \u0000The Mw3.5 seismic event occurred in a 36 m thick dyke called BV78. A tunnel that was damaged by the seismic event passed through the source region. The compact conical-ended borehole overcoring (CCBO) technique was applied at two sites along the tunnel; one site was in an area de-stressed by mining and the other about 10 m from the dyke in an area of increased stress owing to the mining abutment above. DCDA was also applied to the core samples. \u0000Three boreholes (Hole A, Hole B and Hole C) that reach an aftershock area in the upper margin of the source fault of the Orkney earthquake (Mw5.5), were drilled by the ICDP-DSeis project (Ogasawara et al, 2019). Since the holes were designed to be drilled in the direction of the maximum compression, borehole breakout or core discing rarely occurred. The DCDA was applied to core samples recovered from Hole A and Hole B. The DRA was also applied to core samples of Hole A. The differential and the normal stresses along Hole A showed a spatial variation that correlates with a variation in lithology and the aftershock distribution.","PeriodicalId":213743,"journal":{"name":"Proceedings of the Ninth International Conference on Deep and High Stress Mining","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133949179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An evaluation of the bond strength of multiple resin bolt and capsule combinations through laboratory testing and applied methodologies","authors":"Irene A. Bierman, L. Gardner, P. Piper","doi":"10.36487/ACG_REP/1952_14_BIERMAN","DOIUrl":"https://doi.org/10.36487/ACG_REP/1952_14_BIERMAN","url":null,"abstract":"This paper describes the implementation of a methodology and test results to determine the performance capability of a combination of O 20 mm steel tendon resin bolts from ten separate suppliers, and O 32 mm resin capsules from four separate suppliers. The methodology chiefly describes the parameter of the selected hole diameter which was O 38 mm. Installing O 20 mm resin bolts inside O 38 mm holes results in an excessive annulus, which significantly reduces the bond strength of the installation. By conducting a programme of laboratory pull testing by combining each resin bolt and resin capsule installed inside steel tubes with O 38 mm internal diameter, the best combinations could be determined. The pull tests were supplemented by conducting similar installations inside Perspex tubes to provide visual observation of the installation process. In the laboratory, the test results showed that modified resin bolts provided the greatest resistance to pulling load with the least displacement. The modifications increased diameter of the penetrating end of the bolt, either by the addition of deformities to the steel, or by incorporating a helix into the design of the bolt profile. The work done addressed the need by Impala Platinum Limited (Impala Platinum) for effective resin bolt installations in large diameter holes.","PeriodicalId":213743,"journal":{"name":"Proceedings of the Ninth International Conference on Deep and High Stress Mining","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131412327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fracture model for rockburst mitigation based on the strain energy concept","authors":"R. Zepeda, G. Krstulovic","doi":"10.36487/ACG_REP/1952_19_ZEPEDA","DOIUrl":"https://doi.org/10.36487/ACG_REP/1952_19_ZEPEDA","url":null,"abstract":"Rockbursts constitute an operational problem in deep excavations where many mitigation attempts using different methodologies were used without achieving workable, palliative strategies . The mitigation method with the highest number of bibliographic references is pre-conditioning of rocks prone to this phenomenon. \u0000Pre-conditioning seeks to lower the strength of the rock, ideally by increasing the number of fractures in it, and by extension, increasing its deformation response to imposed stress. \u0000The hydraulic fracturing technique or the use of explosives has been described in the literature as means to induce fractures in the rock mass just ahead of mining. The former method is the most popular in Chile. \u0000To date, there is not enough analytical explanation on how pre-conditioning can mitigate rockburst occurrences. In this paper, the laws of classic mechanics are described in terms of the strain energy to explain the pre-conditioning effect on the rockburst phenomenon; and arising from this, possible limitations of the hydraulic fracturing technique currently in use.","PeriodicalId":213743,"journal":{"name":"Proceedings of the Ninth International Conference on Deep and High Stress Mining","volume":"131 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127022385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new method to evaluate dynamic bolts and the development of a new dynamic rock bolt","authors":"B. Darlington, M. Rataj, W. Roach","doi":"10.36487/ACG_REP/1952_16_DARLINGTON","DOIUrl":"https://doi.org/10.36487/ACG_REP/1952_16_DARLINGTON","url":null,"abstract":"Until science advances our current understanding of the demands and capacity of ground support, empirical design, rather than scientific methods, must be used. When considering ground support capacity, the industry has developed a significant database of laboratory dynamic tests on rock bolts. However, a methodology has not yet been developed to translate these laboratory test results into the in situ dynamic capacity of ground support systems. Recent development and implementation of in situ testing of dynamic bolts, provides a significant improvement in evaluation and interpretation of test results. In situ testing is carried out using a portable dynamic test rig (DTR), which simulates a seismic event through a dynamic impulse applied to a test bolt. This new tool also provides an opportunity to study the effects of mining progression on bolt performance. The DTR was utilised to test the recently developed D47 MDX bolt. The 47 mm diameter MDX bolt was tested at various hard rock mines in Australia with a typical 25 kJ dynamic impulse, causing bolt displacement typically between 100mm to 150 mm.","PeriodicalId":213743,"journal":{"name":"Proceedings of the Ninth International Conference on Deep and High Stress Mining","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129203730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rock reinforcement solutions case study: Malmberget iron ore mine, Sweden","authors":"P. Bray, A. Johnsson, H. Schunnesson","doi":"10.36487/ACG_REP/1952_15_BRAY","DOIUrl":"https://doi.org/10.36487/ACG_REP/1952_15_BRAY","url":null,"abstract":"Finding rock reinforcement solutions for poor rock conditions has attracted increased attention in recent years. While modern face drilling, long hole drilling, truck and loader technologies are able to improve productivity, rock reinforcement has become the bottleneck point in the drill and blast process. As a result, the overall productivity of underground hard rock mining has essentially stalled, especially as mines go deeper and deeper in the pursuit of orebodies. Commonly used bolt designs are not necessarily designed for ease of mechanised installation, resulting in long installation times and uncertain installation quality. The industry needs a step change in order to move forward. \u0000As part of the ground control work package of the Sustainable and Intelligent Mining Systems (SIMS) initiative, Luossavaara-Kiirunavaara AB (LKAB) and Epiroc Rock Drills AB partnered in a project to develop a rock bolting system solution to improve the productivity, flexibility, quality and safety of mechanised rock reinforcement. \u0000This paper illustrates the project background, development stages, implementation and results from new technologies that have provided significant improvements in rock bolt and mesh installation at LKAB’s Malmberget underground operation.","PeriodicalId":213743,"journal":{"name":"Proceedings of the Ninth International Conference on Deep and High Stress Mining","volume":"6 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120900375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seismic Response to hydraulic fracturing in caving mines","authors":"D. Birch, S. Meyer","doi":"10.36487/ACG_REP/1952_33_BIRCH","DOIUrl":"https://doi.org/10.36487/ACG_REP/1952_33_BIRCH","url":null,"abstract":"We present qualitative observations of the recorded rock mass response to hydraulic-fracturing in four case studies from three major caving mines and demonstrate usefulness in the application of advanced seismological methods to describe this response. Three out of the four cases represent a rare opportunity where the seismic response to hydraulic-fracturing was fairly isolated. The activation of structures was readily evidenced using source mechanism analysis. Hydraulic-fracturing applied along the abutment of a cave was shown to be effective in inducing propagation in a highly stressed, stalled section of the cave. The dominant mode of failure in all cases was shear. The amount and type of volumetric change associated with seismicity was dependent on the proximity of the events to mine voids. Seismic activity rates were estimated to be between 10 and 75 times higher during fluid injection than in the time prior to treatment.","PeriodicalId":213743,"journal":{"name":"Proceedings of the Ninth International Conference on Deep and High Stress Mining","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128392318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of stoping activities on tunnel conditions in a deep, hard rock mine in Austria","authors":"T. Ladinig, H. Wagner, A. Daborer","doi":"10.36487/ACG_REP/1952_07_LADINIG","DOIUrl":"https://doi.org/10.36487/ACG_REP/1952_07_LADINIG","url":null,"abstract":"In a deep Austrian hard rock mine, the effect of stoping activities on a mine tunnel situated in the abutment area of a stoping panel, was investigated by means of underground observations and numerical modelling using FLAC 2D and 3D to assess the stress changes resulting from the advancing stopes. This paper discusses the difficulties encountered in quantifying in situ mechanical properties of sheared and jointed rock mass, numerical modelling of the complex geological conditions and relating calculated stress changes to in situ tunnel conditions. It was found that the rockwall condition factor (RCF) tunnel assessment criteria developed to evaluate tunnel conditions in deep South African gold mines, worked remarkably well under very different geological conditions. The focus of this paper is on the approaches adopted to deal with the uncertainties encountered in back analyses and case studies of situations involving behaviour of slender stope pillars, paste fill and regional effects of stoping activities on mine tunnels.","PeriodicalId":213743,"journal":{"name":"Proceedings of the Ninth International Conference on Deep and High Stress Mining","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130595981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The seismic response to mining during the extraction of the Thuthukani shaft pillar, Kloof Operations, South Africa","authors":"Rt Masethe, R. Durrheim, M. Manzi","doi":"10.36487/ACG_REP/1952_06_MASETHE","DOIUrl":"https://doi.org/10.36487/ACG_REP/1952_06_MASETHE","url":null,"abstract":"All seismic data recorded since the extraction of the Thuthukani shaft pillar commenced in January 2007, has been analysed. Seismicity was compared in two five-year periods (1 January 2007 to 30 November 2012 and 1 December 2012 to 31 July 2017). It was found there was an increase in the rate of seismicity and the maximum magnitude (Mmax) from 2.7 to 3. 2.. Strategies to mitigate the seismic risk during shaft extraction are discussed in this paper.","PeriodicalId":213743,"journal":{"name":"Proceedings of the Ninth International Conference on Deep and High Stress Mining","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125168675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Layout design criteria for deep tabular mines: Quo vadis?","authors":"D. Malan, Y. Jooste","doi":"10.36487/ACG_REP/1952_01_MALAN","DOIUrl":"https://doi.org/10.36487/ACG_REP/1952_01_MALAN","url":null,"abstract":"This paper describes aspects related to two design criteria used in the deep gold mines of South Africa, namely, average pillar stress (APS) and energy release rate (ERR). Early layout designs were based on trial and error and most of the recommendations of the 1924 Witwatersrand Rock Burst Committee are still valid today. The introduction of APS and ERR assisted greatly in reducing areas of high stress concentrations. Both criteria are of limited use, however, as it is not clear what the maximum value of APS for remnants should be, and ERR has a significant drawback as no dissipative mechanisms are incorporated to allow for rock failure. A numerical modelling study is described that illustrates the effect of total closure on the simulated APS and ERR values of a remnant. It is recommended that stress measurements are conducted below remnant areas to better calibrate the numerical models.","PeriodicalId":213743,"journal":{"name":"Proceedings of the Ninth International Conference on Deep and High Stress Mining","volume":"155 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114327959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}