Soil stiffness nonlinearity in one-dimensional pile-driving simulations and formulas

Abstract

Driven piles are commonly used as foundation elements in engineering projects. Due to their simplicity, pile-driving formulas have been widely used in practice to estimate static pile capacity based on observations made during pile driving. Existing formulas make no distinction of the soil type surrounding the pile or the pile type. As a result, the prediction scatter is often excessive, with the pile capacity being either largely over- or underpredicted. In this paper, we present new pile-driving formulas for different soil conditions and pile types derived from numerical predictions. The numerical predictions use a set of advanced shaft and base reaction models for dynamic pile-driving analysis that account explicitly for soil stiffness nonlinearity and hysteresis. The ability of the models for reliable back-calculation of static resistance from pile-driving measurements was checked through signal-matching analysis. The proposed pile-driving formulas were validated through well-documented case histories of static load tests on driven piles. It was found that the proposed pile-driving formulas provide reliable predictions of the static pile capacity with less scatter than existing formulas.