Stress Corrosion Cracking and Delayed Increase in Penetration Resistance after Dynamic Compaction of Sand

Abstract

Dynamically compacted sands exhibit a drop in cone penetration resistance immediately after compaction, but a gradual increase in the resistance occurs in a matter of weeks and months. An explanation of this phenomenon is suggested, based on the process of stress corrosion cracking of the micro-morphological features on the surface of the sand grains at the contacts. This process, also referred to as static fatigue, leads to a change in the macroscopic elastic moduli of the sand, which, in turn, causes an increase in the macroscopic horizontal stress under one-dimensional strain conditions. Consequently, delayed increase in the horizontal stress leads to the time-dependent increase in the penetration resistance of the sand bed.