三轴压缩条件下冻融单裂隙岩样裂缝贯通机制

采用岩石力学伺服试验机，对预制单裂隙模型试样进行冻融循环后的三轴压缩试验，基于冻融循环试验对裂隙岩体的冻融损伤劣化模式进行研究，探讨经历不同冻融循环次数后的裂隙岩样在三轴压缩条件下裂缝的贯通机制。试验发现：裂隙岩体的冻融损伤劣化模式有颗粒散落模式、龟裂模式和沿预制裂隙断裂模式3种；在三轴加载条件下，冻融裂隙岩样的贯通模式呈现拉贯通、剪贯通、压贯通和混合贯通4种；贯通模式和冻融循环次数、围压的大小以及裂隙倾角有关，随着冻融循环次数的增加和围压的升高，岩样表面的破裂线越来越多，导致裂纹的贯通模式由单一贯通转换为混合贯通，在围压为2、6 MPa时，岩样的破坏模式为拉-压贯通，而围压为4 MPa时，岩样主要呈现拉贯通，裂隙倾角为30°的岩样主要贯通模式为拉贯通，裂隙倾角为60°的岩样主要贯通模式为剪贯通。

Fracture coalescence mechanism of single flaw rock specimen due to freeze-thaw under triaxial compression

Freeze-thaw test and triaxial compression test are carried out for model samples with pre-existing single fracture by the rock mechanical servo-controlled testing system, freeze-thaw damage degradation model is studied based on the freeze-thaw test, and crack coalescence mechanism is discussed under the triaxial compression condition. Tests reveal that: freeze-thaw damage deterioration modes of fractured rock masses are scattered to particle model, crack model and prefabricated crack fracture mode. Under the triaxial loading condition, there are four coalescence modes of fractured rock samples due to freeze-thaw cycles: tensile mode，shear mode，compression mode and mix mode, which are closely related to the freeze-thaw cycles, confining pressure and the crack dip angle. With the increase of freeze-thaw cycles and confining pressure, more and more surface ruptures are found, at the same time, crack coalescence mode has experienced from single to mix; the failure modes of rock samples show tensile and compression mode when confining pressure reaches the values of 2 MPa and 6 MPa, while tensile mode are presented when the confining pressure reaches the value of 4 MPa. Rock samples with smaller fissure angle which equals 30° are taken on tensile mode, however, the rock samples with the longer fissure angle of 60° take on shear mode.