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Chase K Barnard - One of the best experts on this subject based on the ideXlab platform.
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Application of the refraction microtremor (ReMi) process for predicting change in Rock characterisation and possible correlations with the Rock Mass Rating (RMR)
International Journal of Mining and Mineral Engineering, 2017Co-Authors: Chase K Barnard, Raj R KalluAbstract:In an attempt to provide a more efficient means of determining changes in Rock characterisation, a study was conducted using the refraction microtremor (ReMi) process in an underground mine. ReMi involves acquiring noise data along a linear array of geophones. The data for our study was analysed using the SeisOpt® ReMi™. Various geophone orientations were investigated in order to determine which produced the most discernible dispersion curve. In order to determine whether the changes seen actually exist, shear wave velocities were measured in location of known Rock characterisation. These shear wave velocities were then compared with the Rock Mass Rating (RMR) and previously published correlations between RMR and shear wave velocity. In addition, the use of ReMi as a tool to determine the extent of voids underground was investigated.
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correlation of the Rock Mass Rating rmr system with the unified soil classification system uscs introduction of the weak Rock Mass Rating system w rmr
Rock Mechanics and Rock Engineering, 2016Co-Authors: Sean Warren, Raj R Kallu, Chase K BarnardAbstract:Underground gold mines in Nevada are exploiting increasingly deeper ore bodies comprised of weak to very weak Rock Masses. The Rock Mass Rating (RMR) classification system is widely used at underground gold mines in Nevada and is applicable in fair to good-quality Rock Masses, but is difficult to apply and loses reliability in very weak Rock Mass to soil-like material. Because very weak Rock Masses are transition materials that border engineering Rock Mass and soil classification systems, soil classification may sometimes be easier and more appropriate to provide insight into material behavior and properties. The Unified Soil Classification System (USCS) is the most likely choice for the classification of very weak Rock Mass to soil-like material because of its accepted use in tunnel engineering projects and its ability to predict soil-like material behavior underground. A correlation between the RMR and USCS systems was developed by comparing underground geotechnical RMR mapping to laboratory testing of bulk samples from the same locations, thereby assigning a numeric RMR value to the USCS classification that can be used in spreadsheet calculations and geostatistical analyses. The geotechnical classification system presented in this paper including a USCS–RMR correlation, RMR Rating equations, and the Geo-Pick Strike Index is collectively introduced as the Weak Rock Mass Rating System (W-RMR). It is the authors’ hope that this system will aid in the classification of weak Rock Masses and more usable design tools based on the RMR system. More broadly, the RMR–USCS correlation and the W-RMR system help define the transition between engineering soil and Rock Mass classification systems and may provide insight for geotechnical design in very weak Rock Masses.
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inflatable Rock bolt bond strength versus Rock Mass Rating rmr a comparative analysis of pull out testing data from underground mines in nevada
International journal of mining science and technology, 2016Co-Authors: Chase K Barnard, Sean Warren, Raj R Kallu, Rahul TharejaAbstract:Abstract The purpose of this paper is to establish confidence in anticipated minimum bond strength for inflatable Rock bolts by comparing the bond strength to variable geotechnical conditions using the Rock Mass Rating (RMR) system. To investigate a correlation between these parameters, the minimum bond strength of pull-out tested inflatable Rock bolts was compared to the RMR of the Rock in which these bolts were placed. Bond strength vs. RMR plots indicate that expected minimum bond strength is positively correlated with RMR; however, the correlation is not strong. Cumulative percent graphs indicate that 97% of pull-out tests result in a minimum bond strength of 3.3 and 1.7 ton/m in RMR ⩾ 45 and
Han Kyu Yoo - One of the best experts on this subject based on the ideXlab platform.
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Weightage Effect during Back-Calculation of Rock-Mass Quality from the Installed Tunnel Support in Rock-Mass Rating and Tunneling Quality Index System
MDPI AG, 2019Co-Authors: Jonguk Kim, Hafeezur Rehman, Wahid Ali, Abdul Muntaqim Naji, Han Kyu YooAbstract:In extensively used empirical Rock-Mass classification systems, the Rock-Mass Rating (RMR) and tunneling quality index (Q) system, Rock-Mass quality, and tunnel span are used for the selection of Rock bolt length and spacing and shotcrete thickness. In both systems, the Rock bolt spacing and shotcrete thickness selection are based on the same principle, which is used for the back-calculation of the Rock-Mass quality. For back-calculation, there is no criterion for the selection of Rock-bolt-spacing-based Rock-Mass quality weightage and shotcrete thickness along with tunnel-span-based Rock-Mass quality weightage. To determine this weightage effect during the back-calculation, five weightage cases are selected, explained through example, and applied using published data. In the RMR system, the weightage effect is expressed in terms of the difference between the calculated and back-calculated Rock-Mass quality in the two versions of RMR. In the Q system, the weightage effect is presented in plots of stress reduction factor versus relative block size. The results show that the weightage effect during back-calculation not only depends on the difference in Rock-bolt-spacing-based Rock-Mass quality and shotcrete along with tunnel-span-based Rock-Mass quality, but also on their corresponding values
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Extension of tunneling quality index and Rock Mass Rating systems for tunnel support design through back calculations in highly stressed jointed Rock Mass: An empirical approach based on tunneling data from Himalaya
Tunnelling and Underground Space Technology, 2019Co-Authors: Hafeezur Rehman, Jung Joo Kim, Abdul Muntaqim Naji, Han Kyu YooAbstract:Abstract A preliminary support design is the basic output of an empirical Rock Mass classification system. Tunneling quality index (Q) and Rock Mass Rating (RMR) systems are used specifically for tunnel support in moderately jointed and Massive Rocks; however, they do not provide any information/guidance for jointed Rock Masses in a highly stressed environment. Hence, this study focuses on the already supported drill and blast tunnel sections mapping data of four tunneling projects in Pakistan. The study extends the application of these systems to the tunnel support design for highly stressed jointed Rock Mass through an empirical approach. In each empirical approach, the parameters for the stress condition are suggested. Rock Mass quality (Q or Qc) is determined from back calculations using an installed support and tunnel span. Empirical equations and charts are proposed for the stress reduction factor (SRF) characterization. In the proposed equations and charts, the SRF is a function of intact Rock strength, relative block size, and strength–stress ratio. In the case of the RMR system, approximately 90% of the sections show that the actual supports are heavier than the suggested supports by RMR89. The RMR was determined from the installed support for each tunnel section through the back calculations. To select the adjustment Rating factor for stress, three hypotheses are considered based on the intact Rock strength to the major principal stress ratio. The RMR14 suggested support revealed that all sections are heavily supported. A strong correlation exists between RMR89 and RMR14. Three hypotheses are considered for the stress adjustment factor Rating selection for RMR14 based on the correlation equation between RMR89 and RMR14. For the evaluation, the application of modified Q and RMR systems are used in the tunnel support in a case study. The exploration reports show that the tunnel will pass through a jointed Rock Mass under high in-situ stress environments. The comparison shows that heavy support is recommended from the modified systems for tunnel stability.
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Review of Rock-Mass Rating and Tunneling Quality Index Systems for Tunnel Design: Development, Refinement, Application and Limitation
Applied Sciences, 2018Co-Authors: Hafeezur Rehman, Jung Joo Kim, Wahid Ali, Abdul Muntaqim Naji, Rini Asnida Abdullah, Han Kyu YooAbstract:Although Rock-Mass Rating (RMR) and tunneling quality index (Q) systems are used in different Rock engineering projects as empirical design tools, their application in tunnel design is widely accepted as these systems were developed and updated for this purpose specifically. This paper reviews the work conducted by various researchers since the development of these two systems with respect to tunneling only. Compared to other empirical classification systems, these systems received international acceptance and are still used as empirical design tools in tunneling due to their continuous updates in the form of characterization and support. As the primary output of these systems is the initial support design for tunnel, however, their use in the calculation for Rock-Mass properties is an essential contribution of these systems in Rock engineering design. Essential for the tunnel design, these Rock-Mass properties include the modulus of deformation, strength, Poisson’s ratio, Mohr-Coulomb parameters and Hoek-Brown constants. Other application for tunneling include the stand-up time and Rock load. The uses and limitations of these systems as empirical tunnel design tools are also included in this review article for better results. Research to date indicates that if the ground behavior is also taken into account, the application of these empirical systems will be more beneficial to the preliminary design of tunnels.
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Empirical Evaluation of Rock Mass Rating and Tunneling Quality Index System for Tunnel Support Design
Applied Sciences, 2018Co-Authors: Hafeezur Rehman, Jung Joo Kim, Abdul Muntaqim Naji, Han Kyu YooAbstract:The primary output of the Rock Mass Rating (RMR) and tunneling quality index (Q) system is a preliminary tunnel support design, as these methods are empirically developed and updated for this purpose. In this study, these internationally accepted design tools are evaluated to improve results for tunnel support design. The Rating system is simplified and improved for some parameters through the use of equations to replace the discrete/lump characterization with a continuous Rating. Recent developments in characterization and support are used in proposing the back analysis approach of Rock Mass quality calculation from tunnel span and installed support. This approach is used for two tunnel projects which experience high stresses. Approximately 90% of the tunnel sections show that actual supports have Rock bolt spacing and shotcrete thickness which are heavier than those indicated by RMR89, indicating a system limitation. Another assessment using RMR14 indicates that its Rating is higher than that of RMR89. A strong correlation exists between them, as supported by the literature and data from analyses of 462 tunnel sections. Despite its new version, RMR89 still preserves its importance. Evaluating the different correlations between RMR and Q through published data indicates that the Rock Mass fabric index gives comparatively better results.
Prasnna Jain - One of the best experts on this subject based on the ideXlab platform.
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Assessment of the Excavatability of Rock Based on Rock Mass Quality: A Case Study from India
Geotechnical and Geological Engineering, 2018Co-Authors: A K Naithani, D. S. Rawat, L. G. Singh, Prasnna JainAbstract:During last five decades many attempts have been made to develop a means of assessing the excavatability of Rock. These classifications have been used to select appropriate excavation systems and equipment used in civil and mining works. Empirical Rating and seismic velocity systems are proposed for the rippability of a Rock Mass. In this paper Rock Mass classification systems i.e. Rock Mass Rating system and tunnel quality index and revised excavatability graph are used for assessing the excavatability of Rock. The aim of this study was to examine how the intact Rock and Rock Mass properties influence the excavatability of Rock surface excavation in granite and gneiss terrain. These methods allow the excavatability of Rock to be assessed rapidly. After detailed study it is concluded that Rock Mass Rating system gave a better assessment of Rock Mass quality than the tunnel quality index and revised excavatability model.
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estimation of the performance of the tunnel boring machine tbm using uniaxial compressive strength and Rock Mass Rating classification rmr a case study from the deccan traps india
Journal of The Geological Society of India, 2016Co-Authors: Prasnna Jain, A K Naithani, T N SinghAbstract:The competency of any TBM in any geological condition is determined by a Rock or Rock Mass breakage process. A 12.24 km long tunnel between Maroshi and Ruparel College was excavated by Brihanmumbai municipal corporation (BMC) to improve water supply system of greater Mumbai, India, using open-type hard Rock tunnel boring machines (TBMs). In this paper an attempt has been made to establish the relationship between Rock Mass characteristics i.e. RMR and UCS of the Deccan trap Rocks and TBMs performance characteristics for 5.83 km long Maroshi–Vakola tunnel section of the Maroshi–Ruparel college tunnel project. To analyze the effect of variable Rock Mass conditions on the TBM performance, the opeRating parameters i.e. thrust force, torque and RPM of the machine, were recorded and intact Rock strength was determined. The effect of Rock Mass properties on machine penetration rate (PR) and the relation with other operational parameters were analyzed. The Rock strength affects the Rock behaviour under compression. When the rolling cutters indent the Rock, the stress exerted must be higher than the Rock strength i.e.; the Rock strength is directly relevant to the performance of TBM. Studies show that the penetration rate decreases with increase in uniaxial compressive strength (UCS). The comparison of measured penetration rate with empirical model developed by Graham, in which, the penetration rate is computed using UCS and average thrust per cutter, showed good agreement with coefficient of determination (R2), i.e. 0.97. The study shows that the TBM performance was maximum in Rock Mass Rating (RMR) range from 40 to 75, while slower penetration was recorded both in very poor and very good Rock Masses.
Anand Singh - One of the best experts on this subject based on the ideXlab platform.
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Rock Mass Characterization using Rock Mass Rating and Encountered Geological Problems in TRT’s Component of Tehri Pumped Storage Plant, Uttarakhand, India
Hydro Nepal: Journal of Water Energy and Environment, 2018Co-Authors: Nishith Sharma, Rajeev Prasad, Anand SinghAbstract:As an integral part of Tehri Hydro Power Complex (HPC) located in the state of Uttarakhand in Northern India; an underground 4x250 MW Tehri Pump Storage Plant (PSP) parallel and close to the existing 1000 MW Tehri Hydro Power Plant (HPP). Tehri PSP is located on the left bank of Bhagirathi River in the district of Tehri about 1.5 km downstream of its confluence with River Bhilangana. The major project components are machine hall, upstream surge shafts, Butterfly valve chamber (BVC), Penstock assembly chambers (PAC), downstream Surge Shafts, a pair of Tail Race Tunnels (TRTs) and outlet structures are in construction stage. During underground excavation, one of the important aspects for a speedy and safe excavation is to characterize Rock Mass for its stand up time. Case history of Himalayan tunnel reveals that Barton’s & Bieniawski’s classification system provide better assessment of the Rock Mass behavior. In TRTs of Tehri PSP, Rock Mass Rating (RMR) classifications were implemented during excavation and based on their Ratings, Rock Mass was supported. Construction stage geotechnical assessments were made, and suitable remedies were adopted for all the components of the project after geological traverses, detailed geological mapping, drift logs and logging of cores was done. This paper deals with Rock Mass characterization of underground structures specially in TRT’s using RMR classification and encountered geological problems during excavation. HYDRO Nepal Journal Journal of Water, Energy and Environment Issue: 23 Year: 2018
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Rock Mass characterization using Rock Mass Rating and encountered geological problems in trt s component of tehri pumped storage plant uttarakhand india
Hydro Nepal: Journal of Water Energy and Environment, 2018Co-Authors: Nishith Sharma, Rajeev Prasad, Anand SinghAbstract:As an integral part of Tehri Hydro Power Complex (HPC) located in the state of Uttarakhand in Northern India; an underground 4x250 MW Tehri Pump Storage Plant (PSP) parallel and close to the existing 1000 MW Tehri Hydro Power Plant (HPP). Tehri PSP is located on the left bank of Bhagirathi River in the district of Tehri about 1.5 km downstream of its confluence with River Bhilangana. The major project components are machine hall, upstream surge shafts, Butterfly valve chamber (BVC), Penstock assembly chambers (PAC), downstream Surge Shafts, a pair of Tail Race Tunnels (TRTs) and outlet structures are in construction stage. During underground excavation, one of the important aspects for a speedy and safe excavation is to characterize Rock Mass for its stand up time. Case history of Himalayan tunnel reveals that Barton’s & Bieniawski’s classification system provide better assessment of the Rock Mass behavior. In TRTs of Tehri PSP, Rock Mass Rating (RMR) classifications were implemented during excavation and based on their Ratings, Rock Mass was supported. Construction stage geotechnical assessments were made, and suitable remedies were adopted for all the components of the project after geological traverses, detailed geological mapping, drift logs and logging of cores was done. This paper deals with Rock Mass characterization of underground structures specially in TRT’s using RMR classification and encountered geological problems during excavation. HYDRO Nepal Journal Journal of Water, Energy and Environment Issue: 23 Year: 2018
Hafeezur Rehman - One of the best experts on this subject based on the ideXlab platform.
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Weightage Effect during Back-Calculation of Rock-Mass Quality from the Installed Tunnel Support in Rock-Mass Rating and Tunneling Quality Index System
MDPI AG, 2019Co-Authors: Jonguk Kim, Hafeezur Rehman, Wahid Ali, Abdul Muntaqim Naji, Han Kyu YooAbstract:In extensively used empirical Rock-Mass classification systems, the Rock-Mass Rating (RMR) and tunneling quality index (Q) system, Rock-Mass quality, and tunnel span are used for the selection of Rock bolt length and spacing and shotcrete thickness. In both systems, the Rock bolt spacing and shotcrete thickness selection are based on the same principle, which is used for the back-calculation of the Rock-Mass quality. For back-calculation, there is no criterion for the selection of Rock-bolt-spacing-based Rock-Mass quality weightage and shotcrete thickness along with tunnel-span-based Rock-Mass quality weightage. To determine this weightage effect during the back-calculation, five weightage cases are selected, explained through example, and applied using published data. In the RMR system, the weightage effect is expressed in terms of the difference between the calculated and back-calculated Rock-Mass quality in the two versions of RMR. In the Q system, the weightage effect is presented in plots of stress reduction factor versus relative block size. The results show that the weightage effect during back-calculation not only depends on the difference in Rock-bolt-spacing-based Rock-Mass quality and shotcrete along with tunnel-span-based Rock-Mass quality, but also on their corresponding values
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Extension of tunneling quality index and Rock Mass Rating systems for tunnel support design through back calculations in highly stressed jointed Rock Mass: An empirical approach based on tunneling data from Himalaya
Tunnelling and Underground Space Technology, 2019Co-Authors: Hafeezur Rehman, Jung Joo Kim, Abdul Muntaqim Naji, Han Kyu YooAbstract:Abstract A preliminary support design is the basic output of an empirical Rock Mass classification system. Tunneling quality index (Q) and Rock Mass Rating (RMR) systems are used specifically for tunnel support in moderately jointed and Massive Rocks; however, they do not provide any information/guidance for jointed Rock Masses in a highly stressed environment. Hence, this study focuses on the already supported drill and blast tunnel sections mapping data of four tunneling projects in Pakistan. The study extends the application of these systems to the tunnel support design for highly stressed jointed Rock Mass through an empirical approach. In each empirical approach, the parameters for the stress condition are suggested. Rock Mass quality (Q or Qc) is determined from back calculations using an installed support and tunnel span. Empirical equations and charts are proposed for the stress reduction factor (SRF) characterization. In the proposed equations and charts, the SRF is a function of intact Rock strength, relative block size, and strength–stress ratio. In the case of the RMR system, approximately 90% of the sections show that the actual supports are heavier than the suggested supports by RMR89. The RMR was determined from the installed support for each tunnel section through the back calculations. To select the adjustment Rating factor for stress, three hypotheses are considered based on the intact Rock strength to the major principal stress ratio. The RMR14 suggested support revealed that all sections are heavily supported. A strong correlation exists between RMR89 and RMR14. Three hypotheses are considered for the stress adjustment factor Rating selection for RMR14 based on the correlation equation between RMR89 and RMR14. For the evaluation, the application of modified Q and RMR systems are used in the tunnel support in a case study. The exploration reports show that the tunnel will pass through a jointed Rock Mass under high in-situ stress environments. The comparison shows that heavy support is recommended from the modified systems for tunnel stability.
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Review of Rock-Mass Rating and Tunneling Quality Index Systems for Tunnel Design: Development, Refinement, Application and Limitation
Applied Sciences, 2018Co-Authors: Hafeezur Rehman, Jung Joo Kim, Wahid Ali, Abdul Muntaqim Naji, Rini Asnida Abdullah, Han Kyu YooAbstract:Although Rock-Mass Rating (RMR) and tunneling quality index (Q) systems are used in different Rock engineering projects as empirical design tools, their application in tunnel design is widely accepted as these systems were developed and updated for this purpose specifically. This paper reviews the work conducted by various researchers since the development of these two systems with respect to tunneling only. Compared to other empirical classification systems, these systems received international acceptance and are still used as empirical design tools in tunneling due to their continuous updates in the form of characterization and support. As the primary output of these systems is the initial support design for tunnel, however, their use in the calculation for Rock-Mass properties is an essential contribution of these systems in Rock engineering design. Essential for the tunnel design, these Rock-Mass properties include the modulus of deformation, strength, Poisson’s ratio, Mohr-Coulomb parameters and Hoek-Brown constants. Other application for tunneling include the stand-up time and Rock load. The uses and limitations of these systems as empirical tunnel design tools are also included in this review article for better results. Research to date indicates that if the ground behavior is also taken into account, the application of these empirical systems will be more beneficial to the preliminary design of tunnels.
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Empirical Evaluation of Rock Mass Rating and Tunneling Quality Index System for Tunnel Support Design
Applied Sciences, 2018Co-Authors: Hafeezur Rehman, Jung Joo Kim, Abdul Muntaqim Naji, Han Kyu YooAbstract:The primary output of the Rock Mass Rating (RMR) and tunneling quality index (Q) system is a preliminary tunnel support design, as these methods are empirically developed and updated for this purpose. In this study, these internationally accepted design tools are evaluated to improve results for tunnel support design. The Rating system is simplified and improved for some parameters through the use of equations to replace the discrete/lump characterization with a continuous Rating. Recent developments in characterization and support are used in proposing the back analysis approach of Rock Mass quality calculation from tunnel span and installed support. This approach is used for two tunnel projects which experience high stresses. Approximately 90% of the tunnel sections show that actual supports have Rock bolt spacing and shotcrete thickness which are heavier than those indicated by RMR89, indicating a system limitation. Another assessment using RMR14 indicates that its Rating is higher than that of RMR89. A strong correlation exists between them, as supported by the literature and data from analyses of 462 tunnel sections. Despite its new version, RMR89 still preserves its importance. Evaluating the different correlations between RMR and Q through published data indicates that the Rock Mass fabric index gives comparatively better results.
