| Fractured rock mass affects the stability of geotechnical engineering, and it is of great engineering significance to carry out research on fractured rock mass. Firstly, single cracks with different angles were set on sandstone samples, and the damage and failure characteristics of fractured sandstone were studied from a macro perspective by indoor uniaxial compression test. The results show that with the increase of crack dip angle α, the peak strength and elastic modulus of the sample increase gradually, and the weakening effect of prefabricated cracks on the mechanical properties of the sample is weakened. The prefabricated cracks reduce the activity level of AE events, and the AE events are most active when α is 90°. With the increase of α, the power-law distribution index of AE energy shows an “N” type change trend of increasing first, then decreasing and then increasing. Secondly, the numerical model of fractured rock mass is established by PFC2D, and the micro-crack propagation law and damage evolution process of fractured sandstone failure process are revealed from the mesoscopic point of view. The number of total cracks and shear cracks in the loading process of the sample increases with the increase of α, while the number of tensile cracks continues to increase. The failure of the sample is a mixed failure of tension and shear dominated by shear failure. In the meso-damage evolution process of the fractured specimen, the meso-microcracks are first initiated at the tip of the prefabricated crack and then extended to the upper and lower ends of the specimen. The number of microcracks in the meso-damage evolution process is distributed in a band, and the distribution of crack hot spots is basically consistent with the macro-crack propagation mode of the indoor test. |
