Soil improvement using compaction grouting - A laboratory investigation on the confining pressure and injection rate in completely decomposed granite

Laboratory compact grouting was performed using a modified triaxial test on Hong Kong CDG (completely decomposed granite) soils to investigate the effect of effective confining pressure and grout injection rate on the compact grouting effect. In this study, compaction grouting was simulated by expanding a latex balloon inside a triaxial sample using de-aired water. When the balloon is expanded, it first needs to overcome the effect of the confining pressure of the soil; further expansion will compact and density the surrounding soil. The compact grouting effect can be control by measuring the total void ratio change during injection and the following consolidation. The injection rate was controlled by a GDS using a volume control technique. The results of the experiments showed that the effective confining pressure on soil specimen plays an important role in the effect of compaction grouting, and the injection rate has an effect on the rate of excess pore pressure dissipation but minor effect on soil density. © 2007 Taylor & Francis Group.