Rate effect on cone penetration test in sand

Abstract

A literature survey has provided quite variable results with respect to rate effect on cone penetration test(CPT) in sand. Most of the available data refer to the penetration rate in the range 2 mm/s – 20 mm/s, and show some rate effect. The analysis of the data shows that the factors controlling rate effect on CPT in sand are excess pore pressure generation (in the case of loose silty sands and loose fine sands) and grain crushing (especially in the case of dense sands). Excess pore pressure generation produces a reduction in cone resistance when the rate is increased from 2 mm/s to 20 mm/s, while the opposite occurs in the case of grain crushing. Since the stress level influences grain crushing, the higher the stress level the higher the rate effect. Moreover, the higher the crushability of the sand grains, the higher the rate effect. There is scarcity of tests at high rates. Few data available from tests with variable high rates indicate a significant rate effect.