Whole process finite element analysis of the load-bearing behavior of slope-stabilizing piles using three-dimensional triple nonlinearity

Slope-stabilizing piles typically are commonly permitted significant horizontal displacement while satisfying the requirement of bearing capacity. The in-situ pile tests of such piles indicate that with a minor thrust and a pile top displacement of less than 10 mm, cracking occurs near the sliding surface of the pile body, leading to non-elastic flexural deformations. Despite this, slope-stabilizing piles are still conventionally treated as elastic in the current design calculations and numerical simulations, resulting in significant discrepancies between expected and actual behaviors. To address such issues, using tested piles as a case study, a concrete pile model with actual reinforcement was established using the Diana finite element program. This model incorporates material nonlinearities such as the total strain crack model, the Von-Mises model, and the hardening soil model to realistically simulate the behavior of the concrete pile, steel bars, and soils, respectively. The analysis further considered the boundary and geometric nonlinearities inherent in pile-soil and soil-rock interactions. Results show high agreement with measured data for displacements at the pile top or along the pile body; the bending moments of the pile body in the pile segments near the top and bottom of the pile, where no cracks appeared, aligned well with measurements. The corresponding load that led to the advent of cracking, and the positions of cracking also highly consistent with experimental observations. For the first time, numerical simulations revealed that as the thrust increases, a double semi- "inverted cone" wedge-shaped shear failure zone forms in front of the pile, consistent with experiment descriptions of triangular wedge deformations and soil shear failures leading to localized reductions in soil resistance. The phenomenon of the decrease of the soil resistances in some places induced by the shear failure of the soil mass was also coincident with the actual situation. The above results demonstrate that the proposed method can evidently enhance the level of the design calculation and analysis of slope-stabilizing piles and demonstrate potential for wider application.