Bonded-particle modeling of thermally fractured granite

A numerical modeling study of a heated rock was carried out and validated by a laboratory experiment. In the laboratory experiment, a granite cylinder with a diameter of 30 cm was fractured by a heater placed in a central borehole. Acoustic emission (AE) monitoring during the experiment showed the development of the damage in the specimen. The numerical simulations were made with a commercially available code PFC2D, using a bonded-particle approach. A total of 15 numerical specimens were built with varying mechanical and thermal properties. During the modeling, AE events were simulated and compared against the laboratory data. The numerical models showed similar failure behavior to that observed in the laboratory experiment. The pre-failure AE events were isolated and randomly located in the sample, while the failure itself appeared as a single large AE event comprising many microcracks aligned along a plane. The results of these unique thermal simulations have been so encouraging that we are proceeding with larger scale thermal problems.