A calculation model has been developed to quantify the influence of consolidation on the grout pressures. For conventional grout the consolidation determines the strength properties of the grout after injection. Increased flow resistance affects the pressure distribution around the tunnel lining and the increased strength of the grout reduces the stress in the tunnel lining due to buoyancy forces. The influence of hardening starts several hours after injection at a larger distance from the TBM. The grout parameters necessary for the model can be measured with the consolidation test, as described. For a tunnel bored in sand the normal situation will be that only a part of the grout consolidates before the grout pressures come nearly equal to the pore pressure. In such a situation the final grout pressure and thus the stress situation in the soil is not determined by the injection strategy but by the properties of the grout and the soil around the tunnel.
展开▼
