Geotechnical engineer, AT&E Consultants, Inc., Norcross, GA
ProfessorMember of ASTM, Louisiana State University, Baton Rouge, LA
Cone penetrometers have been increasingly used in geotechnical investigations during the past several decades. The cone penetration test is recognized as a reliable, simple, fast, and economical in-situ testing technique. Implementation of pore-pressure transducers inside cone penetrometers to monitor the penetration pore pressure during a sounding has strongly increased their applicability and versatility. However, the accuracy of the recorded pore pressures and especially the effect of the degree of saturation of the pore pressure measuring system on the monitored values are debatable. This study is an attempt to provide a deeper insight into this matter.
Theoretical and experimental investigations were conducted. The theoretical work led to the derivation of an equation that may be used to estimate the period of time necessary to achieve an equilibrium inside the pore-pressure measuring system of a partially saturated piezocone. The experimental results revealed that (1) a fully saturated piezocone is capable of responding promptly and accurately to the generated pore pressures during a sounding and (2) the accuracy of the pore-pressure response of a partially saturated piezocone is affected by its degree of saturation as well as the hydraulic conductivity and the geometry of the piezometric element.
Paper ID: GTJ10523J