Volume 32, Issue 4 (July 2009)
Penetration Rate Effect on Miniature Cone Tip Resistance for Different Cohesionless Materials
Cone penetrometer tests were carried out in a 140 mm diameter triaxial chamber by using a miniature cone of diameter 19.5 mm. The rate of cone penetration was varied from 0.01 mm/s to 0.1 mm/s. Tests were performed in (i) clean sand, (ii) silty sand, and (iii) sand added with fly ash. Two different effective vertical pressures (σv), 100 kPa and 300 kPa, were employed. It was noted that for clean and silty sand, the effect of penetration rate on the ultimate tip resistance (qcu) of the cone was found to remain only marginal. On the other hand, for sand added with 30 % fly ash, the variation in qcu values with penetration rate was found to become quite significant. The effect of penetration rate on qcu in all the cases was found to increase with a decrease in the rate of cone penetration. It was noted that with an increase in σv, the effect of penetration rate on qcu was found to become smaller. The effect of the cone penetration rate on qcu generally reduces with an increase in the relative density of the material.