ABSTRACT

This paper describes the planning, material selection, execution and interpretation of the grout injection test carried out FY 2011 at the Grimsel Test Site (GTS) in Switzerland as part of the grouting technology project of the Japan Atomic Energy Agency (JAEA).

Based on the findings of the rockmass characterization part of this study (Nakanishi et al, 2012, Bruines et al., 2012), it was decided to perform the grout injection test in a 5m interval with the highest expected hydraulic conductivity. Three 5m sections in three boreholes located 2m from the injection section were selected for observation. Colloidal silica grout was selected due to the low permeability of the rockmass. Before the grouting test, tracer tests were carried to determine the transport parameters of the test section, and the final silica grout composition for the grouting test.

During the grouting test, the change of viscosity of the grout was continuously measured. Both flow rate and pressure in the injection section were recorded. In the observation sections, the pressure over time as well as the grout concentration, by means of electric conductivity measurements, was recorded.

The grout reached two of the three observation intervals before the grout hardened, which makes the gathered dataset suitable for validating numerical grout penetration models.

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