单轴压缩下混合片麻岩脆性破坏特征分析

Brittle failure analysis of mixed gneiss in uniaxial compression test

岩石单轴压缩变形试验是地下工程勘察中的基本力学试验。本文根据混合片麻岩单轴压缩变形试验的峰前应力—应变曲线,把其破坏过程分为裂纹闭合阶段、线弹性变形阶段、裂纹稳定扩展阶段和裂纹非稳定扩展阶段,并采用滑点回归分析技术得到了混合片麻岩各阶段裂纹临界应力值,即:裂纹闭合应力为23MPa,裂纹起裂应力为45MPa,裂纹损伤应力为86MPa,最后进行了单轴压缩下混合片麻岩脆性破坏过程细观模拟分析,为工程支护设计和围岩破坏机理分析提供参考。

Uniaxial compression deformation test of rock is the basic mechanical test in geotechnical investigation of underground project. According to pre-peak stress-strain curve, the failure process of mixed gneiss is characterized by several distinct deformation stages which include crack closure, linear elastic deformation, stable crack growth and unstable crack growth. The crack damage stress threshold of every stage is determined by the moving point regression technique based on the stress-strain curve. The crack closure stress threshold is 23MPa, the crack initiation stress threshold is 45MPa and crack damage stress threshold is 86MPa. Finally, the microscopic brittle failure process of mixed gneiss is simulated by particle mechanics approach, which is in good agreement with the experiment. The study results provide an important reference for support design and failure mechanism analysis of surrounding rock.