Field investigation of disturbed zones around excavations by strain distribution measurements

The crucial problem of nuclear waste repositories is closely related to the permeability of the host rock mass and its possible change in the course of time. In hard rocks there are preexisting or induced fractures which control flow rather than permeability of the intact rock. Great efforts have been made in recent years to find adequate ways of mathematical modelling of flow through fractured media. The problem lies in the inherent uncertainties concerning the frequency, continuity, direction, interconnection, and hydraulic properties of the rock joints. The complexity of the problem is enhanced by the large volume of the rock mass necessarily involved in the repository performance analysis and also by the coupled processes. It is therefore mandatory to keep abreast of experimental exploratory and field techniques providing a sound basis for the continuing theoretical studies. In fact, one can only develop confidence in long term field observations. This paper addresses problem which arises from the construction of the repository itself