Time-dependent bearing capacity of jacked piles in K₀ consolidated clay based on CPTU tests

Based on the SMP criterion-based K₀ consolidated anisotropic Cam-clay model, an analytical solution to cylindrical cavity expansion for pile installation is derived. This solution incorporates the effects of the initial stress anisotropy, stress history and initial stress-induced anisotropy on the three-dimensional properties of K₀ consolidated clay. According to the similarity of the stress state between the soil adjacent to pile shaft and the soil sample in simple shear tests, a theoretical approach to predict the time-dependent bearing capacity of jacked piles is proposed. This method is based on the axisymmetrical consolidation theory, and the parameters required in this method are only the cone tip resistance, cone base pore water pressure and the corresponding dissipation data from the CPTU sounding. This theoretical approach is verified by the centrifugal model tests, and the time-dependent bearing capacity of jacked piles is studied. The results show that the proposed theoretical method can properly predict the time-dependent bearing capacity of jacked piles, and can avoid the complicated test process of soil properties. The bearing capacity increases rapidly in short time after the pile installation and gradually tends to a stable value. The larger the pile diameter is, the slower the bearing capacity increases and the longer the required time for bearing capacity reaching stable value.