Experimental and Numerical Study of the Mechanical Properties of Granite After High Temperature Exposure

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The macroscopic mechanical properties of granite collected from the Fujian Province, China were measured using uniaxial compression and three-point bending after the granite was exposed to high temperatures. The stress-strain relationship was measured and mechanical properties were calculated. The microstructure and content of minerals are detected. The failure mechanisms and the mechanical characteristics of the granite are explained in terms of the microstructure and the minerals present. Where after the Universal Distinct Element Code (UDEC) was used to numerically simulate the mechanical behavior of granite specimens under uniaxial compressive loading after the granite was exposed to different high temperatures. The model parameters were calculated based on previous experiments. The effects of heat treatment on granite was investigated numerically. The model predictions were compared with experimental results and an acceptable agreement was achieved. A modified failure criterion was developed and a corresponding fish function was written to investigate the development of shear and tensile cracking during loading. It was found that initial cracking is in the form of shear cracks which increase rapidly in number until the model reached the unstable fracture developing stage. The number of tensile cracks increases slowly as the axial stress increases from the crack initiation stress (CIS) to the unstable fracture developing stage. Once the specimen enters into unstable fracture developing stage, there is a transition between the type of failure recorded in the model where the shear cracks change to tensile cracks.