Comparative Analysis of Pile Driving Numerical Modeling Approaches

Driven piles have been commonly used as a suitable deep foundation alternative to the soil conditions in Central Florida. Pile driving is a complex dynamic soil-structure interaction problem that induces vibrations and settlements in the surrounding soils. Numerical models need to be capable of accurately simulating pile dynamics so that the response of soil during the pile installation can be properly assessed. In this paper, numerical analyses were conducted using the finite element platform PLAXIS 2D to compare different modeling approaches used in the technical literature (i.e., continuous versus discontinuous) for the pile driving process. A parametric study was performed to elucidate the role of plastic zones in the process of pile penetration. The constitutive soil model used was the hardening soil model enhanced with small strains (i.e., HS small). Subsurface conditions were determined using laboratory and field-testing data collected from a project site. Input parameters were estimated from subsurface exploration data and processed using GRLWEAP, which is a wave equation analysis program. The concept of a plastic zone with reduced stiffness and strength was introduced around the pile to model the continuous process of pile installation. Based on the results, a continuous pile driving approach matched well with field measurements and provided better insight into the pile-dynamic behavior than a discontinuous modeling approach based on a single blow at various depths. The continuous and discontinuous numerical modeling approaches are compared and discussed associated with pile penetration and velocities at the top of the pile.