Continuous Intrusion Miniature Cone Penetration Test System for Transportation Applications

Abstract

The electronic cone penetrometer is an important investigation tool of choice for in situ site characterization. Application of this proven concept of the cone penetration test (CPT) to transportation applications is described. A miniature cone penetrometer with a projected cone area of 2 cm2 has been developed and implemented in a continuous intrusion miniature CPT system (CIMCPT). This device may be used for rapid, accurate, and economical characterization of sites as well as to determine engineering soil parameters needed in the design of pavements, embankments, and earth structures. The miniature CPT (MCPT) gives finer details than the standard 10-cm2 cross-sectional area reference cone penetrometer, which makes it attractive for subgrade characterization, quality control assessment, compaction control of embankments, and assessment of ground improvement effectiveness for transportation infrastructure. In situ calibration of the CIMCPT system was conducted at a highway embankment site in Baton Rouge, Louisiana. MCPT penetration profiles were compared with those obtained with the standard cone penetrometer at the same site. The tip resistance of the MCPT was 10 percent higher than that of the reference CPT. The sleeve friction and friction ratio of the reference CPT were higher than that of the MCPT by 12 and 23 percent, respectively. Calibration was also performed to determine empirical cone factors required for estimating undrained shear strength from MCPT data.