ABSTRACT

The tail void between the lining and the soil in a tunnel is filled with grout during the construction of a tunnel. This tail void grouting appears to be an important process in tunnelling. This process appears to have an important influence on the resulting settlement trough and on the loading on the lining. Volume changes in the grout after its application in the tail void will lead to surface settlements above the tunnel and/or will change the loading on the lining. Two different mechanisms can lead to volume changes:

1. Bleeding of the grout. The water in the grout is expelled to the surrounding soil when applied in a permeable soil. The amount of bleeding depends on the permeability of the grout, the consolidation properties and the hardening properties.