Simultaneous backfill grouting, pressure development in construction phase and in the long-term.

Simultaneous backfill grouting, carried out for the first time in shield tunnelling in 1982, has been found to be of major importance to design of the tunnel lining and to TBM process control. Developments over the years are discussed, the two-component injection system explained and a typical example given of grout composition and behaviour. A case history of the development of grouting pressure over six months is presented and discussed and an overview given, with field measurements, of about 35 cases with grout pressures at two days after the shield tail has passed. These cases have been grouped as involving soft clays, stiff clays, and sands/sandy gravels. Finally, bending moments in the lining are calculated from measured grout pressure distributions for three cases. A back analysis of a conventional Japanese lining suggests that it is over-designed.
Simultaneous backfill grouting, carried out for the first time in shield tunnelling in 1982, has been found to be of major importance to design of the tunnel lining and to TBM process control. Developments over the years are discussed, the two-component injection system explained and a typical example given of grout composition and behaviour. A case history of the development of grouting pressure over six months is presented and discussed and an overview given, with field measurements, of about 35 cases with grout pressures at two days after the shield tail has passed. These cases have been grouped as involving soft clays, stiff clays, and sands/sandy gravels. Finally, bending moments in the lining are calculated from measured grout pressure distributions for three cases. A back analysis of a conventional Japanese lining suggests that it is over-designed.