A rigorous analytical approach to the pile-soil interaction of torsionally loaded piles in saturated SANICLAY soils

The paper proposes a rigorous analytical approach to predict interaction between torsionally loaded piles and saturated clay soils. The soil deformation mechanism around the pile is determined using the non-associated and anisotropic constitutive model, SANICLAY, along with the axisymmetric condition, equilibrium equation, and boundary conditions. By solving the derived governing equations, the hoop shear stress against rotation curve is obtained, including elastic, elastoplastic, and critical state processes. Taking advantage of the finite-difference method, the torque-rotation behavior of the pile and the stress-strain state of the soil around the pile are figured out. The proposed approach is compared with a FEM simulation and a parametric analysis is conducted to investigate the effect of overconsolidation ratio and in-situ coefficient. Model pile tests and field tests are used to manifest the validity and capacity of the model. The results demonstrate that the present approach can well predict the torque-rotation response of the pile and can reflect some important phenomena observed in pile tests.