Improved a- and β-Methods for the Estimation of Shaft Resistance of Steel-H Piles Driven into Intermediate Geomaterials

摘要

Current driven pile design procedures for H-piles in intermediate geomaterials (IGMs) normally utilize static analysis methods developed for soils (i.e., sands and clays) for estimating side resistance. The purpose of this paper is to assess the performance of a- and p-methods on shaft resistance estimation using 17 test piles driven into IGMs in Wyoming. The necessary pile and geomaterial details were retrieved from an electronic database known as WyoPile. The estimated shaft resistances were compared with that obtained from dynamic load testing results and signal matching analyses results. Ratios of measured to estimated resistances were determined and the associated uncertainties expressed in terms of the coefficient of variation (COV). The comparison identified inconsistent performance of the existing a- and p-methods with relatively high COVs of 1.28 and 0.80, respectively, α and β coefficients were therefore calibrated against IGM properties using regression techniques. The improved a- and P-methods, along with their calibrated design coefficients, were verified using five independent test piles. Due to small sample sizes, the performance of the calibrated a- and β methods could not be conclusively assessed.