Damage accumulation due to microcracking in brittle rock under dynamic loading

This paper presents a constitutive model for the dynamic behavior of brittle rock. The essential feature of this model is the treatment of the dynamic fracture process in rock as a continuous accrual of damage where the damage mechanism is attributed to the growth and interaction of a pre-existing network of microcracks. Damage is measured by the volume fraction of the material which has lost its load-carrying capacity. Damage accumulates only under volumetric tension (hydrostatic or mean stress) and is irreversible in nature. In compression, the model gives an elastic/perfectly plastic material response. The model is implemented into a transient, two-dimensional, solid dynamics finite element code. Comparisons between numerical predictions and field data from an oil shale blasting experiment are made and shown to be in good agreement. 10 refs., 10 figs., 2 tabs.