Time‐Dependent Cone Penetration Resistance due to Blasting

Abstract

Changes in tip resistance, local friction, and friction ratio following blasting in saturated, sandy alluvium are reported. Cone penetration tests (CPT) were performed one week prior to blasting and one, three, and 18 weeks after blasting. Blasting initially decreased the tip resistance by 62%, decreased the local friction by 30%, and increased the friction ratio by 100% of the preblast values. From one week to 18 weeks after blasting, the normalized tip resistance increased by 18%, the normalized local friction decreased by 39%, and the normalized friction ratio decreased by 80% of the postblast values. The rate of increase of normalized tip resistance observed in this research is less than that reported from tests conducted in warmer climates but is greater for tests in colder climates. This suggests that the rate of aging of sands may be temperature‐dependent. Time‐dependent changes in local friction observed in this research have not been reported in the literature.