Tenders should be invited before the end of the year for a 4km long rail tunnel project that includes an 800m long bored section under the river Han in Seoul, Korea.
The Korean National Railway Corporation (KNR) is constructing the Bundang railway line, which branches off the existing Jungangseon line, providing a link between Seoul’s suburbs and the city centre. Four kilometres of the line will be routed underground, between the Wang Shim Rim and Cheongsam stations.
While the majority of the tunnel will be constructed using drill and blast, with a shotcrete lining, the section under the river will be bored. Korean design firm, Yooshin, which designed the tunnel, called on the expertise of German consultants Lahmeyer International. Lahmeyer offered technical advice, assistance on choosing a suitable TBM, and estimation of construction costs.
It is also understood that TBM specialists Herrenknecht and Mitsubishi were part of the consultation process, but no machines have yet been built.
The tunnel will be twin-bore with several connecting cross-passages. Each tube will have an outside diameter of 7.5m and be lined with pre-fabricated concrete segments. The TBM will have to bore through Precambrian primary rocks mostly of granite and gneiss, with the possibility of tectonically disrupted strata. An intense water swell could cause the pressure at the head to reach 5 bars.
KNR has not revealed details of its bidding schedule but tunnelling, should begin by summer 2003.
