Performance of cyclic cone penetration tests in chalk

Abstract

This paper presents results from a preliminary testing campaign to explore the feasibility and benefits of performing cyclic cone penetration tests with measurement of pore pressure (CPTu) in chalk. The CPTu's cone is a miniature driven pile and this technique permits the monitoring of degradation of sleeve friction and pore pressure development during cyclic loading. It was found that while consistent degradation of measured sleeve friction takes place within a few cycles, this was not associated with an observed pore pressure build up. However, uncertainties about the pore pressure measurements arose because the remoulded chalk next to the cone was probably unsaturated and also the pore pressure transducer was positioned close to the tip of the cone. Analysis of the results suggests that the technique may have promising potential to increase understanding of the underlying mechanisms and aid the design of axially loaded driven piles in chalk. Nevertheless further validation and development would be necessary in the future.