STUDY ON CRACK INITIATION MECHANISM OF THREE GORGES GRANITE
三峡花岗岩起裂机制研究

Based on the conventional triaxial compression test of Three Gorges granites,the crack initiation stress under different confining pressures can be obtained by studying the crack strain curves.The result shows that the crack initiation stress changes at the same extent with confining pressure;compared with the peak strength,the crack initiation stress is generally located between 25% and 50% of the peak strength.Through experimental and theoretical analyses,it is found that the microcosmic failure of Three Gorges granites is mainly induced by tensile cracks under uniaxial and triaxial compressive conditions;and the cracks inside the granite belong to I-mode fracture in stable crack growth stage.Furthermore,the fracture mechanical model of Three Gorges granite is established in order to study the relationship between crack initiation stress,crack initiation angle and confining pressure.Some beneficial conclusions are drawn.