Construction of Casting Support Tunneling System using TBM in Water-Bearing Unconsolidated Ground

  • Mr Mamoru Noguchi, Japan Railway Construction, Transport and Technology Agency, Japan
  • Mr Atsushi Ogawa, Japan Railway Construction, Transport and Technology Agency, Japan
  • Mr Tomomi Iura, Japan Railway Construction, Transport and Technology Agency, Japan
  • Mr Tatsuki Tamai, Japan Railway Construction, Transport and Technology Agency, Japan
  • Mr Tsuyoshi Abe, Kajima Corporation, Japan
  • Mr Takashi Kobayashi, Kajima Corporation

The Tsugaruyomogita tunnel is part of the Hokkaido Shinkansen Line. (Fig.1).
The stratum through which the Tsugaruyomogita Tunnel is built is mainly composed of unconsolidated sand below the groundwater level, with extremely high tendency to quicken.
Construction work of the Tsugaruyomogita Tunnel in the same geologic conditions is being performed using a Casting Support Tunneling System using a TBM (hereinafter called SENS) in order to secure digging face. This construction method was firstly developed and adopted in the 3km section in the Sambongihara Tunnel of the Tohoku Shinkansen Line from 2004 through 2006. The SENS construction method entails digging and stabilizing the face using a closed type TBM, supporting the tunnel with an Extruded Concrete Lining (ECL) as the primary lining concurrently with TBM digging and close monitoring to confirm stability, followed by a secondary lining which is not subject to loading.
Excellent result was obtained with SENS during construction of the Sambongihara Tunnel, however, issues were also encountered. In facing those issues, modifications were applied on rapid digging and long distance construction work and, at the same time, concrete casting experiment was conducted by using large scale experiment machine in order to improve quality and performance of primary lining concrete.
This article describes the SENS adopted at the Tsugaruyomogita Tunnel noting the various points improved from the Sambongihara tunnel, test results of the primary lining concrete where modeled experiment machine was used, as well as reports on the current construction work status.