Discrete element simulation of crack growth in a single grain

Abstract

One hypothesis for the origins of creep in sand is that heavily loaded grains may progressively crush following the growth of microcracks due to hydrolysis at crack tips. Weibull’s statistical model of brittle failure can accommodate these time effects. DEM simulations of the temporal deterioration of loaded grains are conducted using Robertson’s (2000) bonded agglomerates of microspheres to represent the grains. It is found that a particular relationship can be derived between the rate of loss of bond strength at a contact and the tension carried at that contact, such that the Weibull modulus of this rate-dependent model matches that of short-term loading tests on individual sand grains. The predicted grain strength decreases in a nearly linear fashion with the logarithm of time, which is in good agreement with results of ceramics obtained by Davidge et al. (1973).