Improved Wave Equation Analysis and Economic Impact Studies for Driven Steel Piles in Rock-Based Intermediate Geomaterials

Abstract Assigning static and dynamic properties to rock-based Intermediate Geomaterials (R-IGMs) remains a challenge in the Wave Equation Analysis Program (WEAP) to accurately predict the pile performance during construction. This was partly attributed to the absence of reliable methods to determine pile resistances in R-IGMs. Furthermore, the recommended Smith parameters are developed based on pile load test data in soils, but not IGMs. Using 95 dynamic load test results of steel H and pipe piles from five state DOTs, improved WEAP and Load and Resistance Factor Design (LRFD) procedures are recommended for piles driven in R-IGMs. The proposed WEAP procedures are based on newly developed static analysis methods and back-calculated dynamic parameters for R-IGMs. Sixteen independent test pile data are collected to validate the recommendations. Compared to the default WEAP procedure, the proposed WEAP procedure reduces the underprediction of pile resistances by 12%, improves reliability by 5%, and yields a higher calibrated resistance factor of 0.70. Our economic impact assessment on 116 test pile data found that the proposed WEAP method yields, on average, a smaller difference in steel weight during construction based on pile types and bearing IGM types.