The effect of overconsolidation and particle shape on the CPT end resistance of granular soils

Abstract

This paper examines the effect of overconsolidation and particle shape on the end resistance (qc) measured in a series of centrifuge Cone Penetration Tests (CPTs) conducted in three uniformly graded silica materials with distinct particle shape. For each soil type, the end resistances were measured for both normally and overconsolidated soil samples at centrifuge g-level of 100g. All samples were prepared and tested at two different relative density, and the over-consolidated samples were achieved by reducing the centrifuge g-level from 200g to 100g (with over-consolidation ratio, OCR=2). At a given relative density and stress level, the striking dependency of the CPTs end resistance (qc) on the particle shape can be observed. For a particular material, a tendency for qc value to increase with the OCR was in evidence. An approach based on the spherical cavity expansion method was proposed to predict the qc value of each soil, and particularly to investigate how the OCR and particle shape influence on the end bearing resistance. It was found that the predicted qc are shown to match the measured data well, and the end bearing resistances were significantly affected by the critical friction angle and horizontal stress, which were closely related to the particle shape and overconsolidation ratio.