Cut-off Effect by Rock Grouting in the Area of Dam-foundation

The cut-off effects of rock grouting at the dam construction sites are investigated such as RQD, unit injected cement volume, Lugeon value and maximum grout pressure in the test holes. Consolidation and curtain grouting have been carried out to obtain mainly the cut-off effect against the leakage water. Lugeon tests before and after grouting in the bedrock are performed in order to estimate the permeability improved at both pilot holes and check holes. Test results show the change of permeability before and after grouting at each site. This paper presents the relationship between Lugeon values and RQD, the relationship between Lugeon values and unit injected cement volume, and the relationship between RQD and unit injected cement volume to derive any quantifiable relationship between the two factors. Finally, at the Site 2, it showed that how average injection cement volume and average Lugeon value are affected by the injection stage of adjacent injection holes from consolidation and curtain grouting.