Compaction grouting has many applications and provides very appropriate solutions to different problems of ground improvement. However, it is usually considered ineffective in treating the relatively shallow soils. This paper describes and presents the results of a field test conducted to investigate the effectiveness of treatment by compaction grout piles. The test consisted of eighty-seven compaction grout piles injected in three cases of different pile diameters and spacings. The results of treatment by the three cases are comparatively discussed for the shallow injections and significant conclusions are made on the effectiveness-controlling factors, variation of effectiveness with depth and variation of improvement with injection.
Compaction grouting as a ground improvement technique involves the injection of very stiff grout into the soil. The objective is to densify and compact the treated soils. The grout material may be formed as singular bulbs or as grout piles. The grout material and grouting procedure are described in the literature (e.g., Warner and Brown, 1974). The applications of the technique are many and increasing (e.g., Baker et al., 1981; Boulanger and Hayden, 1995; Graf, 1992). For many problems, compaction grouting provides very appropriate solutions that may necessitate extending the grouting zone to few or very few meters from the ground surface. However, it is usually considered ineffective in treating the relatively shallow soils. Therefore, an effective planning of the compaction grouting works entails understanding for the shallow injections the effectiveness-controlling factors and the variation of attainable improvement with depth. To the authors' knowledge, no efforts have been made to investigate the effectiveness of shallow treatment by compaction grouting. A field test consisting of eighty-seven compaction grout piles injected in three cases of different pile diameters and spacings was conducted to investigate the effectiveness of treatment.
