Soil deformation around a penetrating cone in silt

Laboratory-scale cone penetration tests (CPTs) in silt were performed with x-ray micro tomography and analysed with three-dimensional digital image correlation. During insertion of the instrumented probe, these tools allow the identification of a contractant bulb of silt close to the tip of the probe surrounded by a larger bulb of dilating material. The results obtained (in particular the failure mechanisms observed) shed new light on the mechanics of cone penetration in silt and consequently reflect on the interpretation of in situ CPTs.