Development of a Finite-Difference–Discrete-Element Coupled Model for Ram-Compacted Bearing Base Piles

Ram-compacted bearing base (RBB) piles have been utilized as an effective foundation technique in China over the last 20 years. RBB is an enlarged technique for base piling that has proven to be a more economical and environmentally friendly solution than traditional piling methods. However, this technique remains unexplored in Western countries, and there have been only limited studies on the modeling and design of RBB piles. This paper discusses the development of three-dimensional (3D) numerical modeling of RBB piles by coupling the finite-difference method (FDM) and the discrete-element method (DEM). The explicit FDM program FLAC3D (version 7.0) was used to simulate the behavior of soil surrounding the pile wherein the material is represented by a number of continuum zones. The 3D DEM software Particle Flow Code (PFC3D7.0) was also used to simulate the flow and interaction of rubble particles through deformable contacts and time-domain solution of the equation of motion. The strengthened layer where the rubble base is constructed was simulated using a bonded particle model. The performance of the developed FDM-DEM model was then validated by comparing its results with site test results obtained from three case histories, and the outcomes were found to be in good agreement.