Pile capacity prediction in Minnesota soils using direct CPT and CPTu methods

A test pile program was performed consisting of static loading tests on two test piles, a 304 mm diameter and a 406 mm diameter steel pipe pile. A seismic piezocone (SCPTu) sounding was performed at the test pile site, and the results of the static loading tests are compared with published direct Cone Penetration Test me- thods, three CPT based methods and three CPTu based methods, to evaluate the ap- propriateness for use of these methods in this area. It was found at this site that direct CPTu based capacity methods predicted more accurately than CPT based methods, and provided very good agreement, all within 20%, of the results of static loading tests taken to failure. In addition, the results of down hole seismic shear wave veloci- ty tests taken during advancement of the SCPTu sounding are applied to elastic conti- nuum theory to evaluate the axial load-movement response. The results at this site are in very good agreement to the conventional top-down static loading test results.