• Title, Summary, Keyword: Rock mass rating

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A Study of Simple Rock Mass Rating for Tunnel Using Multivariate Analysis (다변량분석을 이용한 터널에서의 간편 RMR에 관한 연구)

  • 위용곤;노상림;윤지선
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.493-500
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    • 2000
  • Rock Mass Rating has been widely applied to the underground tunnel excavation and many other practical problems in rock engineering. However, Rock Mass Rating is hard to make out because it is difficult to estimate each valuation items through all kind of field situations and items of RMR have interdependence. So the experts of tunnel assessment have problems with rating rock mass. In this study, using multivariate analysis based on domestic data(1011EA) of water conveyance tunnel, we presented rock mass rating system which is objective and easy to use. The constituents of RMR are decided to RQD, condition of discontinuities, groundwater conditions, orientation of discontinuities, intact rock strength, spacing of discontinuities in important order. In each step, we proposed the best multiple regression model for RMR system. And using data which have been collected at other site, we examined that presented multiple regression model was useful.

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An Evaluation of Rock Mass Rating System As Design Aids in Korea (RMR 분류법의 국내 적용성 평가)

  • 구호본;배규진
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.209-216
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    • 1994
  • Rock mass classifications have played an indispensable role in underground construction for several decades. An important issue in rock mass classifications is the selection of the parameters of greatest significance. There appears to be no single parameter that can fully describe a jointed rock mass for underground construction design. In this paper. We find some problems shen applied rock mass classification for underground construction in domestic, analyze the most significant parameters and parameters correlation influencing the behavior of a rock mass, and suggest the Simplied Rock Mass Rating system based on RMR method for effective underground supports.

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Study on the stability of tunnel and rock mass classification in Danyang limestone quarry (단양 석회석 광산터널의 암반 평가 및 안정성 연구)

  • ;Choon Sunwoo;Kong Chang Han;yeon-jun Park
    • Tunnel and Underground Space
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    • v.6 no.2
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    • pp.131-143
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    • 1996
  • In-situ survey and laboratory rock test were carried out for rating rock mass around the tunnel that some failures had been occurred in Danyang limestone quarry. For rating rock mass, several methods such as RMR, Q-system, rock strength etc. were applied. The stability analysis on tunnel was evaluated by numerical method FLAC. And The block theory using streographic projection was also applied for stability analysis. The 3-4 major discontinuity sets are distributed in rock mass around tunnel.

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A Study of Efficient Rock Mass Rating for Tunnel Using Multivariate Analysis (다변량분석을 이용한 터널에서의 효율적인 암반분류에 관한 연구)

  • Wye, Yong-Gon;No, Sang-Lim;Yoon, Ji-Son
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.2 no.2
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    • pp.41-49
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    • 2000
  • Rock Mass Rating has been widely applied to the underground tunnel excavation and many other practical problems in rock engineering. However, Rock Mass Rating is hard, even by the experts of tunnel assessment owing to lack of investigation system. In this study, using multivariate analysis we presented rock mass rating system that is objective and easy to use. The constituents of RMR are decided to RQD, condition of discontinuities, groundwater conditions, intact rock strength, orientation of discontinuities, spacing of discontinuities in important order. In each step, we proposed the best multiple regression model for RMR system.

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Applicaton of a Geomechanical Classification for Rock Slope (암반 사면에 대한 새로운 암반 분류안의 적용)

  • 김대복
    • Tunnel and Underground Space
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    • v.4 no.3
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    • pp.215-227
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    • 1994
  • Rock Mass classifications have been developed in many European countries. The most widely used classification methods are the Rock Mass Rating (RMR) system proposed by Bieniawski(1973) and the Q-system developed By Barton et al. (1974). These methods are also adopted at many mountain tunnels and subway sites in our country. Here, a geomechanical classification for slopeds in rock, the "Slope Mass Rating"(SMR) is presented for the preliminary assessment of slope stabiliyt. This method can be applied to excavation and support design in the front part of tunnel and cutting area as a guide line and recommendation on support methods which allow a systemmetic use of geomechanical classification for rock slopes.

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Assessment of rock slope stability by slope mass rating (SMR): A case study for the gas flare site in Assalouyeh, South of Iran

  • Azarafza, Mohammad;Akgun, Haluk;Asghari-Kaljahi, Ebrahim
    • Geomechanics and Engineering
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    • v.13 no.4
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    • pp.571-584
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    • 2017
  • Slope mass rating (SMR) is commonly used for the geomechanical classification of rock masses in an attempt to evaluate the stability of slopes. SMR is calculated from the $RMR_{89-basic}$ (basic rock mass rating) and from the characteristic features of discontinuities, and may be applied to slope stability analysis as well as to slope support recommendations. This study attempts to utilize the SMR classification system for slope stability analysis and to investigate the engineering geological conditions of the slopes and the slope stability analysis of the Gas Flare site in phases 6, 7 and 8 of the South Pars Gas Complex in Assalouyeh, south of Iran. After studying a total of twelve slopes, the results of the SMR classification system indicated that three slope failure modes, namely, wedge, plane and mass failure were possible along the slopes. In addition, the stability analyses conducted by a number of computer programs indicated that three of the slopes were stable, three of the slopes were unstable and the remaining six slopes were categorized as 'needs attention'classes.

A study on correlation between electrical resistivity obtained from electrical resistivity logging and rock mass rating in-situ tunnelling site (전기비저항 검층으로 얻은 전기비저항과 터널 현장 암반등급의 상관관계에 관한 연구)

  • Lee, Kang-Hyun;Seo, Hyung-Joon;Park, Jin-Ho;Ahn, Hee-Yoon;Kim, Ki-Seog;Lee, In-Mo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.14 no.5
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    • pp.503-516
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    • 2012
  • Rock mass rating (RMR) is the key factor when designing the appropriate support pattern of tunnel projects. Borehole drilling is usually performed along the tunnel route in order to determine the rock mass rating to be used for tunnel design. The rock mass rating at the non-boring region between boreholes is usually assessed through geophysical surveys such as electrical prospecting, seismic prospecting, etc. Many studies were carried out to find out the correlation between electrical resistivity and rock mass rating. However, most researches were aimed at obtaining the relationship between the two parameters utilizing experimental results obtained from laboratory tests or electrical prospectings. In this paper, efforts were made to analyze and obtain relationships between the electrical resistivity obtained from in-situ electrical resistivity logging data and the rock mass rating. Correlation studies using field data showed that the electrical resistivity is highly correlated with the rock mass rating with the determination coefficient more than 90%. The correlation analysis was also carried out between RMR classification parameters and the electrical resistivity. It was shown that the correlation between the condition of discontinuities and the electrical resistivity was very high with the determination coefficient more than 80%; that between the groundwater condition and the electrical resistivity was very low with the determination coefficient less than 57%.

A study on the Correlation Between the Result of Electrical Resistivity Survey and the Rock Mass Classification Values Determined by the Tunnel Face Mapping (전기비저항탐사결과와 터널막장 암반분류의 상관성 검토)

  • Choi, Jai-Hoa;Jo, Churl-Hyun;Ryu, Dong-Woo;Kim, Hoon;Oh, Byung-Sam;Kang, Moon-Gu;Suh, Baek-Soo
    • Tunnel and Underground Space
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    • v.13 no.4
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    • pp.279-286
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    • 2003
  • Many trials to set up the correlation between the rock mass classification and the earth resistivity have been carried out to design tunnel support type based on the interpreted electrical resistivity acquired by surface electrical survey. But it is hard to find reports on the comparison of the real rock support type determined during the excavation with the electrical resistivity by the inversion of the survey data acquired before the tunneling. In this study, the rock mass classification based on the face mapping data and the resistivity inversion data are investigated to see if it is possible to design reliably the rock support type based on the surface electrical survey. To get the quantitative correlation, rock engineering indices such as RCR(rock condition rating), N(Rock mass number), Q-system and RMR(rock mass rating) are calculated. Since resistivity data has low resolution, Kriging method as a post processing technique which minimizes the estimated variance is used to improve resolution. The result of correlation analysis shows that the 2D electrical resistivity survey is appropriate to see the general trend of the geology in the sense of rock type, though there might be some local area where these two factors do not coincide. But the correlation between the result of 3D survey and the rock mass classification turns out to be very high, and then 3D electrical resistivity survey can make it possible to set up more reliable rock support type.

A study on the correlation between the result of electrical resistivity survey and the rock mass classification values determined by the tunnel face mapping (전기비저항탐사결과와 터널막장 암반분류의 상관성 검토)

  • 최재화;조철현;류동우;김학규;서백수
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.265-272
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    • 2003
  • In this study, the rock mass classification results from the face mapping and the resistivity inversion data are compared and analyzed for the reliability investigation of the determination of the rock support type based on the surface electrical survey. To get the quantitative correlation, rock engineering indices such as RCR(rock condition rating), N(Rock mass number), Q-system based on RMR(rock mass rating) are calculated. Kriging method as a post processing technique for global optimization is used to improve its resolution. The result of correlation analysis shows that the geological condition estimated from 2D electrical resistivity survey is coincident globally with the trend of rock type except for a few local areas. The correlation between the results of 3D electrical resistivity survey and the rock mass classification turns out to be very high. It can be concluded that 3D electrical resistivity survey is powerful to set up the reliable rock support type.

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REVALUATION OF (지공학적 암반분류의 재평가)

  • 김교원
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.33-40
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    • 1993
  • The Bieniawski's geomechanics classification system(1984) is widely employed as a tool of engineering evaluation of rock masses for tunnel design. Since the siz parameters adoped in the system are believed to control the engineering behavior of rock mass under an external load, no question may be raised to the conceptional idea immanent in the system. However, the rating grade for each individual parameter given in the system may be properly measured since an engineering property of rock mass is not stepwise changed but continuously changed. In order to get the proper rating grade based upon the continuously changed properties in each parameter, several equations presented in this paper are obtained through regration analyses with the grades and median values of properties givne in the system. A FORTRAN computer program given in the paper could provide not only RMR value but also rock mass properties (E, c, o, v, etc.) using the empirical equations.

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