Evaluating axial drilled shaft response by seismic cone

The axial load-displacement-capacity of drilled shaft foundations can be conveniently evaluated using the results of seismic piezocone penetration tests (SCPTU) to provide continuous profiles of small- and large-strain soil properties. The penetration readings (qT, fs, and ub) reflect soil limit states that are utilized to obtain the side and base components for capacity, while the initial soil-pile stiffness is assessed from measurements of downhole shear wave velocity (Vs) via elastic continuum theory. An equivalent elastic modulus coupled with degradation scheme provides nonlinear representation with increasing load level. Load transfer from top to base is considered and the approach can accommodate homogeneous to generalized Gibson-type soil conditions. A recent load test case study is presented for a drilled shaft situated in Piedmont residuum for an interstate highway bridge in Coweta County, GA