Fracture dilation during grouting

Sealing underground excavations from ingress of water constitutes a large part of both the cost and the risk for many infrastructure projects. In this paper we present a mechanical model for the rock mass response when grouting hard jointed rock. The model predicts a stiff and a non-stiff behaviour and a transition between them that is dependent on the relationship between the grouting pressure and the in situ stress conditions. The predictions are consistent with previously published measurements and explain grouting behaviour that has been difficult to model with previous methods.