Variable Penetration Rate Cone Testing in Sands with Fines

Piezocone penetration rate effects are well documented in theoretical, laboratory, and centrifuge studies. Field implementation has been explored, but mostly in uniform deposits where soil conditions are well characterized. Standard cone penetration rates typically develop fully drained penetration in sands and fully undrained penetration in clays. The presence of fines in sandy soils may create a partial drainage condition at the standard 2.0 cm/sec rate. Partial drainage may be eliminated by adjusting the penetration rate proportional to soil drainage characteristics. This study presents considerations for variable penetration rate cone tests and results from field implementation at two Northern California sites. Controlled penetration rates from 0.002-20 cm/s are used to establish drained conditions at each site. The significance of drainage condition, normalized velocity penetration rate, state estimates, and spatial variability is also discussed.