| Dynamic fracture properties of rock is closely related to load conditions and temperature.Rock materials in different engineering temperature, present different fracture damage.Therefore,in-depth study what the temperature effect on dynamic mechanical properties of rock materials, test the dynamic fracture toughness of rock at different temperature has important theoretical and practical significance to structure design, prevent rock fracture, crushing, slip and rheological.Based on the principles of Central Cracked Circular Disk-Split Hopkinson Pressure Bar(CCCD-SHPB) test, platform Brazilian disc was used to study temperature effect on rock fracture properties, in the experimental by controlling the pulse load, make the loading rate of the specimens are almost the same, the testing temperature is the only change conditions. The dynamic stress intensity factor is achieved by extending the quasi-static formula of the stress intensity factor. Taking the time when the average load of the two side of the specimen securing the maximum value Pmax as the initiation time of crack. Taking the Pmax into dynamic formula of the stress intensity factor to calculate the dynamic fracture toughness of the specimens.Test results show that the temperature is10℃to100℃, the dynamic fracture toughness increased with the temperature gradually decreased, approximate linear relationship.Take the experimental loads as simulation load in the FEM model.Calculate the dynamic stress intensity factor of center disk specimen under near field and far field solutions.Results showed that the far field and near field solution is consistent, thus the dynamic formula of the stress intensity factor is reliable.In this paper, we use the black granite and white granite as experiment materials.The black granite test results show that when the loading rate keep in139250(MPa·m1/2s-1), temperature from10C to100℃, as the temperature gradually decreased, dynamic fracture toughness declined steadily from8.0(Mpa· m1/2) to6.5(Mpa·m1/2)in linear relationship.The white granite test results show that when the loading rate keep in101144(MPa·m1/2s-1), temperature from10C to100℃, as the temperature gradually decreased, dynamic fracture toughness declined steadily from5.7(Mpa·m1/2) to4.5(Mpa·/m1/2) in linear relationship basic. |
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