Static and Dynamic Pile Load Tests on Steel H-Piles in Intermediate Geomaterials

The transitional behaviors of intermediate geomaterials (IGMs) between soil and hard rock create relatively high uncertainties in designing and constructing driven piles in IGMs. The performance and acceptance of driven piles in IGMs are often evaluated using dynamic load test (DLT) methods. Although dynamic methods offer considerable technical and economic benefits, a static pile load test (SLT) is warranted to understand the static behavior of driven piles in IGMs. This paper presents three static and dynamic load tests of steel H-piles in IGMs. Test pile 1 (TP1) was driven into siltstone in Wyoming, and the other two test piles (TP2 and TP3) were driven into shale in Iowa. Vibrating wire strain gauges were installed along each pile length to determine the shaft resistances and end bearing. Each pile was axially loaded, and pile top displacements were measured. Two different pile load systems (independent and integrated) were designed for the SLT. Four failure criteria were used to determine the ultimate pile resistances. It was observed that DLT underpredicted the total pile resistances of TP1 by about 33%, 20%, and 24% when compared to SLT results based on Davisson, 10% B, and De Beers YL criteria, respectively. Compared with the De Beers’ YL criterion for TP2, DLT underpredicted the total pile resistance by 11% and shaft resistance by 60%, but overestimated the end bearing by 15%. For TP3, DLT underestimated total pile resistance by 9%, 11%, and 11% compared with the three criteria, respectively.