Jet Grouting and Soil Mixing for Increased Lateral Pile Group Resistance

Abstract

Lateral load tests were performed on a full-scale pile cap in clay before and after construction of shallow soilcrete walls produced by soil mixing and jet grouting on either side of the pile cap. This relatively simple approach increased the lateral resistance of the pile cap by 60% for soil mixing and 160% for jet grouting. For the soil mixed wall, essentially all of the increased resistance was due to passive pressure and side/base shear against the soil mixed wall as the pile cap pushed the wall laterally. However, for the jet grout wall, about 25% of the increased resistance came from soil-pile interaction because the jet grout wall extended under the cap and against the piles. Soil mixing and jet grouting provide a means to significantly increase the lateral resistance of existing pile group foundations with relatively little investment of time, effort, and expense relative to adding more piles.