三轴压缩条件下单裂隙岩样裂隙扩展研究

Triaxial Compression Condition Order Fracture Rock Fissure Extension Study

含天然裂缝和层理岩体的断裂破坏是由其内部裂隙起裂、扩展、汇合成宏观剪切带直至失稳破坏引起的。通过对含单裂隙岩样开展三轴加载试验,并采用PFC^(2D)数值模拟软件,研究岩样在不同围压和裂隙长度条件下的力学性质与裂纹的起裂、扩展和破坏规律。结果表明:当围压为7 MPa时,岩样以剪切-拉伸复合破坏模式为主;当围压为14 MPa时,岩样以Y型剪切破坏、单一斜剪破坏模式为主;当围压为21 MPa时,岩样以X型剪切破坏模式为主。围压越大,岩样的强度与弹性模量越高,岩样的破坏越明显;预制裂隙越长,岩样的强度与弹性模量越低,裂纹扩展的规模越大。随着围压的增加,拉裂纹占比逐步增加。围压与预制裂隙长度增大,岩样破裂带范围越广。该研究成果对于揭示含单裂隙岩体的扩展与破坏规律具有重要的参考价值。

The fracture failure of rock mass with natural fractures and bedding is caused by the initiation,expansion,and convergence of internal fractures into macroscopic shear zones until instability failure.The triaxial loading test was carried out on the rock sample with a single fracture,and the PFC^(2D) numerical simulation software was used to study the mechanical properties of the rock sample and the crack initiation,propagation and failure laws under different confining pressure and fracture length conditions.The results show as follows.When the confining pressure is 7 MPa,the shear-tensile composite failure mode is the main failure mode.When the confining pressure is 14 MPa,the specimen mainly adopts Y shear failure mode and single oblique shear failure mode.When the confining pressure is 21 MPa,the specimen mainly adopts the X shear failure mode.The greater the confining pressure,the higher the strength and elastic modulus of the rock sample,and the more obvious the damage of the rock sample.The longer the prefabricated fracture,the lower the strength and elastic modulus of the rock sample,and the larger the scale of crack propagation.With the increase of the confining pressure,the proportion of tensile cracks gradually increases.The confining pressure and the length of the prefabricated fractures increase,the wider the fracture zone of the rock sample.The research results have important reference value for revealing the propagation and failure law of rock mass with single fracture.