Tunnelling and Underground Space Technology 17 (2002) 391–401
0886-7798/02/$ - see front matter ᮊ 2002 Elsevier Science Ltd. All rights reserved.
PII: S0886-7798
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02
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00063-9
Comparison among different criteria of RMR and Q-system for rock mass
classification for tunnelling in Korea
S.Y. Choi, H.D. Park*
School of Civil, Urban and Geosystem Engineering, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul, 151-742, South Korea
Received 4 March 2002; received in revised form 26 June 2002; accepted 8 July 2002
Abstract
Recent increase in the number oftunneling projects in Korea resulted in a large amount ofgood quality data such as RMR
and Q-value for the assessment of rock mass class. In addition, a new bidding system, so-called Turn-Key system, has also made
the data quality better than ever before, due to the increase of the budget for site investigation. A conventional guideline for rock
mass classification by KHC (Korea Highway Corporation) has been widely used in Korea but other forms of classification using
different criteria of RMR or Q-value have been recently used. Since there have been few studies on the relationship among such
different criteria on RMR or Q-value, this study mainly focuses on the comparison of the conventional guideline for rock mass
classification with several individual classification schemes in Korea. Analysis of the coincidence among the different criteria
using both RMR and Q-value showed that there is higher coincidence ifrock mass is in relatively good condition. It was also
found that there is less consistency between RMR criteria and Q-value criteria in conventional KHC Guideline for rock mass
classification than the recently adopted individual criteria.
ᮊ 2002 Elsevier Science Ltd. All rights reserved.
Keywords: RMR; Q-system; Tunnel design
1. Introduction
In Korea, a new stage ofconstruction ofthe highway
network has been planned to provide a good transpor-
tation system which is required by the increase of
domestic consumer as well as the export industry. A
total 2294 km ofhighway on 21 lines are in operation
in November 2001 and the total length ofhighway is
planned to be 3400 km up to 2004 (Fig. 1).
Due to the high percentage ofmountainous area in
Korea, up to 70%, tunneling work has been very
frequently included in the construction of many roads
and railways. In addition, such a big demand on the
high speed railways and highways leads to more tun-
neling works recently because of the effort to keep the
line as straight as possible. Total length ofhigh-speed
railways is up to 412 km from Seoul to Busan and the
first stage of the construction project for Seoul–Daegu
*Corresponding author. Tel.: q82-2-880-8808; fax: q82-2-871-
8938.
E-mail address: hpark@gong.snu.ac.kr (H.D. Park).
section is in progress. The second stage ofthe construc-
tion project for Daegu–Busan section is scheduled to
start in 2002. All 46 tunnels (67 km long in total) in
Seoul–Daegu section have been completely excavated.
There is also a tendency to construct long tunnels up to
a few kilometers more and more (Table 1).
In addition, a change ofbidding system for construc-
tion, i.e. a new system, so-called Turn-Key bidding
system, which is based on the total quality ofthe
construction plan, not merely on the minimum cost for
construction, resulted in a significant change in site
investigation process for the tunnel, which had to be
conducted within a very restricted budget previously. It
is not unusual to spend much more money than before
for the site investigation of the ground condition. As a
result, an enormous amount ofrelatively better quality
data, when compared with the previous tunneling works
in Korea, have been recently available to tunneling
engineers. Better interpretation could be possible with
the aid of many different techniques available, such as
analysis ofremotely sensed imaging and a variety of
geophysical survey methods. One ofthe most important