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Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
(a) Underpass box #3
(b) Hadong IC-Ramp
Figure 4 Location map of construction methods
4 CONSIDERATIONS OF DESIGN STANDARD
If the highway crossing tunnel on weathered deposit soil is
evaluated unsafe, it should be redesigned to improve the safety.
To perform proper evaluation regarding some purposes and
methods, evaluating methods of tunnel safety should be
compared. Settlement, displacement, stability are not enough to
be evaluated for tunnel stability according to Tunnel Design
Criteria in Korea (MLTM of Korea,2007; Bjorn, 2011).
Therefore, coded techniques of the information of trenchless
tunnel should be introduced considering above contents of
construction types and evaluation methods in manuals as in
Table 5. For more detailed maintenance, information of tunnels
should be filed through the coded numbers of structure types
and locations, design and construction conditions, geotechnical
data, tunnel section, settlement, safety inspection, etc.
Table 5 Coded techniques of tunnel construction
Items
Code
Detailed items
L-G-1 Geotechnical data
L-G-2 Drainage etc.
Geological
investigation
L-G-3 Standard related
L-D-1 Analysis, Planning
L-D-2 Stability of structure
Design
L-D-3 Design drawings, etc.
L-E-1 Excavation equipments
L-E-2 Monitoring
L-E-3 Ground settlement
L-E-4 Unstable condition
Excavation
L-B-5 Soil layers , etc.
L-C-1 Support
L-C-2 Concrete lining
Construction
L-C-3 Reinforcement, etc.
L-O-1 Facilities
L-O-2 Slope around bell mouth
L-O-3 Safety inspection
Operation &
maintenance
L-O-4 Monitoring, etc.
Design standard-based system of trenchless tunnel, which is
defined as single source responsibility for design and
construction, has been widely used in large public works in
Korea since the government launched plan in 1996. However,
as large market share of design and work volume are becoming
hot item in construction sites. To measure the efficiency of
global design standard-based system for the improved system
by assessing domestic design projects using information about
equipment, quality, and new technology adoption from case
projects of highway crossing tunnels including modifying
design standard.
5 CONCLUSIONS
In this study, a
case history of the underground trenchless
tunnel for the highway crossing in urban area of Korea is
reviewed. Several points were summarized form the case
history as the following.
The actual ground state of tunnel was worse than predicted
in design. The remediation measures included ground and
tunnel reinforcing by grouting method and reinforced grouting
method, respectively, and invert constructing using steel-
reinforced concrete lining, particular in highway crossing tunnel.
Existing trenchless methods insert stiff structure
(rectangular type pipes or circular type pipes) to lower part
under the ground in order to protect existing roads or structures
before excavation of tunnels.
Design standards of newly developed trenchless tunnel
technology have to specify retainment of history files of
structures, coded system of failure types of structures, reliability
analysis for geotechnical data determination. Owing to change
of design considerations according underground condition,
revising contents of design guidelines of tunnels should be
followed after comparisons of design manuals for other upper
and lower structures, such as foundations, concrete structures,
retaining walls, etc.
6 ACKNOWLEDGEMENTS
This work is also a part of the result from the “Maintenance of
Foundation Design Criteria under the Construction Facilities for
Standardization”, the “Construction & Transportation R&D
Policy and Infrastructure Project.
7 REFERENCES
Bjorn, N. (2011). Hard rock tunneling with particular focus on
deep subsea tunnels in difficult conditions, Lectures for
New Horizons by eminent scholars, Korea. 10-25.
Kim, N.Y., Yang, T. S., Woo, S. B. (2012). A case study on the
excessive displacement of rear face under construction road
tunnel in Korea, 3
rd
International on New Developments in
Soil Mechanics and Geotechnical Engineering, 109-115.
H
an
, S. S, (2012). A Study on pressurizing trenchless method
for displacement control, Master degree Dissertation.
Dongyang University, Korea. 4-35.
Kim, D. Y., Lee, H. S. and Sim, B. K. (2012). Development of
trenchless tunneling method using pressurizing support and
its field application, Proceedings of the spring conference of
the Korean Geotechnical Society, 239-254.
Daemen, J.J.K.(1977), Problems in tunnel support mechanics.
Underground Space, Vol.1,p.163-172.
MLTM of Korea (2007), “Manual for design standard of
tunnel”, published by Korean Ministry of Land, Transport
and Maritime Affairs, 26-122.
