Field Behavior of Jet Grouting Pile under Vacuum Preloading of Soft Soils with Deep Sand Layer

Abstract

Vacuum preloading is a successful ground improvement technique. However, when the soil layers include a sand layer, the vacuum pressure decreases sharply in the layer with high permeability, which leads to poor efficiency for deeper soft soil. This paper presents a case study on the application of high pressure jet grouting pile to prevent vacuum preloading from leaking in the silty sand and silty clay layers. The piezocone penetration test was using to determine the thickness and depth of sand. The field test results show that sealing effectiveness of the high pressure jet grouting piles is excellent, and the main settlements of deep soft soil layer can be eliminated effectively by vacuum preloading. The physical and mechanical properties of the soft soil are improved greatly after being consolidated. The success of this project would promote greatly the application of vacuum preloading, and this study provides a reference for similar ground improvement projects using the proposed method.