脆性岩石侧向变形特征及损伤机理研究

进行了三峡花岗岩常规三轴压缩、保持轴向应变和保持轴向应力的卸围压试验,研究了脆性岩石在不同应力路径和不同加载控制方式下的侧向变形特征,可见临界侧向应变均稳定在(-0.004 ± 0.000 5)范围内.进一步进行三峡花岗岩的全过程应力-应变曲线和损伤力学分析,发现脆性岩石在不同应力路径和不同加载控制方式下均以侧向损伤为主,且侧向损伤曲线的形态近似,达到临界破坏状态时损伤值稳定在0.7～0.8左右.最后以侧向损伤变量表征花岗岩脆性破坏过程,建立了基于应变空间的、可以考虑卸荷应力路径的损伤模型和应变型破坏准则.

Study on lateral deformational characteristics and damage mechanism of brittle rock

For the Three Gorges granite specimens, the conventional triaxial compression and the confining pressure reduction test under constant axial strain and stress are carried out. The lateral deformational characteristics of brittle rock under different stress paths or different loading control modes are studied; and it is found that the critical lateral strains are always in the range of ?0.004 5 and ?0.003 5. Based on the analysis of the complete stress-strain curves and the damage mechanism of the Three Gorges granite, it is put forward that the brittle rock mainly occurs lateral damage and exhibits the similar damage evolutionary rule under different stress paths and loading control modes; and the critical failure generally occurs at a damage variable level of 0.7 to 0.8. Finally, a damage model considering the unloading effect and a failure criterion in strain space are established, in which the lateral damage variable is seen as a critical variable.