Rate Dependence of Penetration Resistance in a Cohesive Soil

Penetration resistance of soils is described in a Poncelet framework in which it is due to the sum of an inertial drag term and a strength-related bearing stress. The problem addressed in this paper is how to determine the Poncelet bearing stress from a conventional cone-penetrometer test (CPT). For the case of a particular saturated sandy clay, it is shown that strength has an exponential dependence on strain rate, determined from unconfined compression experiments, which can be used to account for the difference in strength between a CPT carried out at 0.02 m/s and the strength resisting projectiles traveling impacting at 140–200 m/s. With that correction, the CPT tip resistance can be taken as the Poncelet strength.