Abstract: This paper compares the analytical and numerical solutions of the cavity expansion theory based on calculations using the 3D finite difference software FLAC3D. By simulating pile-soil friction using the displacement penetration method, comparison of the result of applied nodal force is in good agreement with the literature. Based on the simulation method, calculation and analysis of the  static pressure single pile, double pile driving process, and impact on the displacement of the pile driving from driven pile, the following conclusions can be reached: The horizontal displacement on the surface is bigger. The
reason is constraintting the radial displacement when the pile body move downward at a constant speed which is in order to prevent the circular hole necking. After pile driving, the depth range of more than 1/8 pile length is the main deformation area, so the horizontal displacement is bigger. The upper soil subsidence is bigger than the lower region. The largest settlement appears below the surface by 1/8−1/4 of the pile length. Pile driving process makes the pile a bit tilt. Due to the impact of the pile driving reaming, the soil uplifts along the driven pile because of the pile barrier. This is the substance of the masking effect, achieving the purpose of reducing horizontal displacement by changing the distribution of soil displacement.

Key words: cavity expansion theory, displacement penetration method, masking effect;static pressure pile