Principles and Nethods of Compaction and Fracturing Grouting for Foundation Soil lmprovement

Both compaction grouting and fracturing grouting are effective to strengthen foundation soils,because the net of grouting veins induced by fracturing grouting similar to the grout bubbles induced by compaction grouting can densify their adjacent soils as well as increase the sum of principal stresses.Asa result,the compression modullus and the cone penetration resistance of the foundation soil increase.The effectiveness of fracturing grouting is not evident until a large amount of grout is injected, Whilst,compaction grouting can soon improve a soil of small volume by injecting very limited amount of grout.But for a large volume of soil to be treated, fracturing grouting is cheaper and easier to perform. Frac-turing grouting is suitable for foundation soil of large volume,while compaction grouting is applicable toboth large and small vblume.Quick injection of very thick grout is an effective way of controlling com-paction grouting,however,it is usually transferred to fracturing grouting.On the contrary,fracturinggrouting is easy to control and is unable to transfer to compaction grouting.