A Numerical Study of Chamber Size and Boundary E ects on CPT Tip Resistance in NC Sand

Abstract

A numerical modeling procedure was used to quantify calibration chamber size and boundary e ects for cone penetration testing in sand. In the numerical analyses, chamber diameter and boundary conditions were varied to investigate the e ects of chamber size and boundary conditions on cone tip resistance. These analyses show that, for loose sand, a chamber-tocone diameter ratio of 33 is su cient for the boundaries to have no in uence on the cone tip measurements. However, for very dense sand, the numerical analyses show that the chamberto- cone diameter ratio should be more than 100 to ensure that boundaries have no in uence on cone tip measurements. Numerical analysis indicates that, not only the sand relative density but its stress state is also a signi cant factor in in uencing the chamber size e ects. The results of the numerical analyses were compared to existing empirically based relationships. Suggestions are provided to reduce the e ects of chamber size and boundaries on cone tip resistance measurements in sand.