Axial Capacity of Piles Supported on Intermediate Geomaterials; Final rept

摘要

The natural variability of intermediate geomaterials (IGMs) exacerbates uncertainties in deep foundation design and may ultimately increase construction costs. The study was undertaken to investigate the suitability of conventional pile capacity formulations to predict the axial capacity of piles driven into IGM formations. Data from nine Montana Department of Transportation bridge projects were collected, compiled, and analyzed. Axial pile analyses were conducted using a variety of existing methods and computer programs, including: DRIVEN, GRLWEAP, FHWA Gates driving formula. WSDOT Gates driving formula, and an empirical method used by the Colorado Department of Transportation. The results of the analyses were compared to pile capacities determined using PDA measurements obtained during pile driving and wave equation analyses conducted using the CAPWAP program. The capacity comparisons clearly demonstrated the inherent variability of pile resistance in IGMs. Most of the projects exhibited considerable variation between predicted capacities calculated using DRIVEN and measured CAPWAP capacities.