5. Conclusions
This paper analyzed and discussed remedial grouting techniques applied over ten years to five existing deteriorated dam clay core layers. For remediation grouting of dam embankment cores, a totally different design concept is required compared to typical pressurized grouting applications, such as dam foundation or coffer dam grouting. Remediation grouting without reservoir water drawdown is known to be e ffective; however, case history reports on this topic are rare, and no empirical standards for applying the method have been presented. In this paper, low-pressure remediation grouting techniques were applied to five existing cored dam embankments that showed either exterior or interior de ficiencies in core impermeability. The dams exhibited embankment deterioration of the following types: randomly distributed fluidized cores of high water content, wet downstream surfaces, sinkholes on the crest, downstream slope failure, or granular cores in the areas adjacent to the dam crest. Various validation methods demonstrated that site-speci fic lowpressure permeation grouting can effectively remediate dams by improving the impermeability of deteriorated core layers. Fundamental empirically proven technical speci fications are proposed, including limits on the grout pressure, grout flow rate, injection duration, initial grout mix ratio, additive ratio, and grouting condition change. Signature characteristics of the most commonly e ffective remedial permeation grouting techniques include the following.
