The injection pressure is an important parameter in the practice of compaction grouting. It is usually used in the limiting criteria and has the potential for use as an improvement evaluation criteria. A guideline on which the limiting injection pressure can be determined is unavailable and the effects of soil properties on the injection pressure have not been evaluated. In this paper, the results of two field tests are presented and discussed to evaluate the effects of soil intrinsic parameters on the injection pressure. Based on the presented results and discussions, good correlations between the injection pressure and both the fines content (Fc) and mean particle size (D50) of the soil are established.
The applications of compaction grouting as a ground improvement technique are many and increasing. It has been used, for example, to compact loose fills or natural loose soils and to reduce the liquefaction potential of in-situ soils during earthquakes (e.g., Graf 1992; Boulanger and Hayden 1995). The compaction grout is a very stiff material, usually a mixture of fines-containing aggregate, cement and water. During injection, the grout material increases in size and remains in a homogeneous mass that displaces the surrounding soils through a distinct grout-soil interface. This results in a controlled densification of the surrounding soils. The grout material may be formed as globular bulbs injected into discrete soil zones or as compaction grout piles. The compaction grout piles are usually injected using the bottom-up procedure by starting from the bottom of treatment zone and staging upward. The procedure of compaction grouting and its applicability are well documented in the literature (e.g., Warner and Brown 1974; Graf 1992). The injection process is usually performed until reaching a given limiting criterion which may be a pre-determined grout volume, injection pressure or ground surface upheave.
