Numerical simulation of pile installations in a hypoplastic framework using an SPH based method

This paper presents a tool to estimate the stresses, and thus the expected forces, at a retaining wall by the installation of piles. The solution method is based on Smoothed Particle Hydrodynamics (SPH) and the soil is modeled using a simplified hypoplastic material law. In order to correctly compute the forces on the soil due to the contact between the pile and the soil, a formulation for imposing frictional boundary conditions using SPH is developed. Modeling the soil with the chosen hypoplastic approach also allows for tensile forces in the soil. However, these are not physical. Therefore, an alternative formulation is presented which directly eliminates unphysical tensile stresses in the cohesionless soil without any additional numerical parameters. The numerical code is firstly validated against benchmark problems. Then several test cases are simulated including monotonic and cyclic penetration of piles into the soil. A good agreement with the experimental observation is found. Additionally, the impact of pile driving in the presence of sheetpiles (retainers) is investigated to see how the pile driving can alter the applied forces on the sheet piles. The simulation of such complex geotechnical problems that involve large deformation, material nonlinearity, and moving boundary conditions demonstrates the applicability and versatility of the proposed numerical tool in this field.