( State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China)
Abstract：In order to study the characteristics and mechanism of brittle failure of granite，the triaxial compression tests under different confining pressures were conducted and the scanning electron microscopy(SEM) were carried out. The microscopic characteristics of failure surface and the brittle failure mechanisms were discussed. In the range of the confining pressures adopted in the experiment，the granite showed strong characteristics of brittle failure and had no brittle-ductile transition. In addition to the oblique shear failure fracture，a kind of Y-shaped failure surface also appeared. The brittle failure of granite is governed by the occurrence of the plastic deformation and the scope and extent of the plastic yielding during the pre-failure period. The different mineral compositions and microscopic structural differentiations are the internal mechanism of brittle failure. The magnitude and the speed of the stress drop during the post-failure period are the external manifestations of the intensity of the brittle failure of granite. The speed of post-failure stress drop is determined by the interconnecting speed of macroscopic fractures which depends on the energy accumulation in granite. Whether the macroscopic fractures are interconnected completely determines the magnitude of post-failure stress drop.
MARTIN C D. Seventeenth Canadian geotechnical colloquium：the effect of cohesion loss and stress path on brittle rock strength[J]. Canadian Geotechnical Journal，1997，34(5)：698-725.
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2014, Vol. 33 
