PREDICTION OF GROUTABILITY FROM GROUT PROPERTIES AND HYDROGEOLOGICAL DATA

Sealing tunnels and caverns in fractured crystalline rocks has been co nsidered notoriously unpredictable and possible to manage only through experience and intuitive Knowledge. Words such as ''witchcraft'' and ''black art'' have been used ironically in Sweden to describe the stat e of the art. In this paper, initially grout penetration and grout tak e in parallel planar fractures are discussed. General expressions for these entities are also derived for fractures with varying width. In t his paper the grout take of a system of inhomogeneous channels in a fr acture plane is studied further and the grout takes of such systems ar e modelled numerically. Grout, takes are calculated for increased vari ability of the fracture aperture and the influence of this is assessed In normal Swedish grouting procedures, the grouting boreholes are tes ted by water pressure tests (WPT). The hydrogeological information fro m these tests can be transferred to grouting apertures, and thus yield design information for grouting operations. Finally, the applicabilit y of the findings is evaluated using field data from grouting of the a ccess tunnel of the Aspo Hard Rock Laboratory, Sweden. The conclusion is that field methods for prediction and design of grouting operations can successfully be based on the theory.