Geology Reference
In-Depth Information
Appendix E-1 Example of tunnelling risk assessment at
South Korea
The Young Dong Railroad Relocation Project for the Korean National
Railways (KNR) included a single-track railway tunnel, in rock,
approximately 16.3 km long with a span of approximately 8m. As at
2011 it is the longest tunnel in Korea. The tunnel had to be constructed
as a large radius loop to limit the gradient of the track, as illustrated in
Figure AE-1.1.
The maximum depth of the tunnel is approximately
400m, with most of the alignment being at depths in excess of 100m.
The route for the tunnel was identi
ed as having intrinsic hazards
including:
potentially high water pressures, up to 40 bars (4 MPa) pressure
-
fault zones, possibly associated with signi
cant groundwater
-
in
ows
-
highly sheared and closely jointed rocks
-
some rocks with high strength and abrasivity
-
possible cavernous limestone with groundwater
old mine workings (coal).
-
Halcrow, with Nick Swannell as Project Manager, was commissioned
to advise a consortium of contractors tendering for the construction of
the tunnel and as part of the brief carried out a thorough hazard and
risk assessment of the route for both TBM and drill and blast options.
Several state-of-the art reports by Dr Graham Garrard of Halcrow
were based on existing ground investigations along the route, mapping
and further GI together with an in-depth review of tunnel case histories
in similar terrain throughout the world by Dr. Laurie Richards.
A risk assessment method was developed to make a quantitative and
objective assessment of the construction methods of the tunnel. The
risks associated with tunnel excavation are dependent on the hazards
encountered and were de
ned for this project with respect
to
