Field-test investigation on influence of soft soil by continuous jet grouting

This paper presents a case study of an investigation into the responses of the surrounding soil to the continuous jet grouting in soft soil deposits of Ningbo. During the field test, an automatic intelligent monitoring system was set up to monitor vertical and lateral displacement of ground surface, lateral displacements of the subsurface soils, and the variation of pore-water pressure induced by the installation of jet grouting piles (JGPs). The monitoring results showed that the construction of the jet grouting piles caused a large deformation of the surrounding soil. At a distance of 1.5 m from the construction area, the maximum vertical displacement and horizontal displacement could reach 179.54 mm and 180.31 mm. With the increase of distance, although the influence gradually weakened, the values of the two were still 5.8 mm and 18.98 mm at a distance of 15 m from the construction area. The excess pore pressure of the surrounding soil caused by the construction could reach 124.9 kPa. Notably, the construction of the rotary jet pile has a great influence on the surrounding soil. The installed piles can reduce the impact of the installation of the following piles. In soft soil foundation, the influence of jet grouting cannot be mitigated by stress relief holes.