The effect of the development of undrained pore pressure on the efficiencyof compaction grouting

Compaction grouting involves the injection of stiff grout that does not pen etrate the ground. Bulbs of grout are formed. It is applied to free-drainin g granular soils. The aim is to increase the density of the soil being trea ted by applying high local pressure. The design of compaction grouting is b ased largely on experience and empiricism. If the soil is not sufficiently permeable for consolidation to occur as it is treated, excess pore pressure s may be generated, which will dissipate after treatment. The potential eff ect of such excess pore pressures on the compaction achieved is considered here. It is found that the efficiency of treatment may be reduced substanti ally.