Axial Uplift Behavior of Pressure-Injected Footings in Cohesionless Soil

The pressure-injected footing (PIF) can develop significant uplift capacity in cohesionless soils. This high capacity is developed mainly by the unique shape of the PIF and the soil compaction effect caused by the installation process. In this paper, a rational approach is proposed for evaluating the axial uplift capacity of PIFs in cohesionless soils. This approach is based on the general effective stress model used for drilled foundations, taking into account the special construction effects that alter the in-situ soil conditions and the unique PIF geometry. Case histories of axial uplift load tests were collected and analyzed, and it was found that three distinct effects were evident: (a) compaction effect, (b) shape effect, and (c) change in stress state. These factors were quantified from the available data. The resulting analysis model that incorporates these factors is versatile and can be used to evaluate the axial uplift capacity of PIFs in a straightforward and rational manner.