Simulation of rock fracturing using particle flow modeling: Phase I - Model development and calibration

This paper presents part of the results for the first phase of the research on simulating rock fracturing with particle flow modeling, using the three dimensional Particle Flow Code (PFC3D). The first phase work focuses on development and calibration of the numerical model based on the micro structure and laboratory mechanical test data (unconfined compressive strength, tensile strength and stress-strain curves) of real rocks. The results show that although the unconfined compressive strength can be well simulated using the standard PFC3D model, the tensile strength is over predicted and leads to unconfined compressive strength to tensile strength (UCS/T) ratios significantly lower than the laboratory test value. Two different methods have been used to improve the simulation results and increase the UCS/T ratio. The contact bond release model which simulates the pre-existent micro cracks in rock can double the UCS/T ratio from the standard PFC3D model but still under-predicts the UCS/T ratio. The near sphere clump particle model containing 50% clump particles only slightly improve the simulation results. Other methods and/or a combination of different methods need to be studied in order to develop a PFC3D model which can correctly simulate the mechanical behavior of real rocks.