Calibration Chamber Studies of Piezocone Test in Cohesive Soils

Abstract

Results of miniature piezocone penetration tests (PCPT) on cohesive soil specimens in a calibration chamber system are presented. The influence of soil type, stress history, penetration boundary conditions, and filter locations on PCPT data are investigated. An increase in the strength of the soil around the cone penetrometer is observed when penetration is resumed after a dissipation test. The penetration depth required to attain a steady excess pore pressure value at the tip of the cone is influenced by the overconsolidation ratio and the lateral stress coefficient. The empirical values of the cone factor and the pore pressure factor are found to be strongly influenced by the lateral stress and the plasticity index. The tip resistance measured during the miniature quasi‐static friction cone penetration tests (QCPT) are consistently lower than the values obtained from the PCPT. Interpretation of the dissipation results to evaluate the radial coefficient of consolidation should be based on the initial dissipation values of the excess pore pressure, and not the penetration pore pressure.