Miniature Cone Tip Resistance on Sand in a Centrifuge

Abstract

Miniature cone penetration tests were conducted in centrifuge models to investigate the effects of various testing conditions on the tip resistance including the particle size, centrifugal acceleration related to stress level and prototype cone diameter, container wall boundary, and penetration rate. Two sand materials were selected: (1) Saemangeum and (2) silica sands. The former is natural sand with high fine contents and the latter is clean sand. A series of penetration tests was performed in six saturated soil models using an in-flight robot. Three Saemangeum sand models were prepared by means of the moist compaction method. The silica sand models were made by the air-pluviation method. Modeling of models was adopted to investigate the particle size effect using 7-, 10-, and 13-mm-diameter cones. The centrifugal acceleration effect also was studied by comparing the tip resistance profiles obtained at different g-levels using the 10-mm-diameter miniature cone. The results indicated that the particle size effect was negligible for both sands using 7-to 13-mm-diameter cones. However, the tip resistance decreased with increasing g-level at a shallower depth than a given critical depth (D-cr), especially for dense sand. Then, it merged to a single value at a deeper depth than D-cr. The D-cr was affected by g-level and soil density. Finally, an empirical correlation to estimate the soil density from the tip resistance in the centrifuge was proposed.