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为研究含双裂纹试件力学破坏特性,为评价底板突水危险性提供理论依据.通过在真实岩石试件中预制双裂纹,基于MTS伺服控制试验机进行单轴、三轴压缩试验,并结合RFPA数值模拟,研究含双裂纹试件损伤演化和裂纹扩展过程.结果表明:1含双裂纹试件破坏模式具有明显的围压效应,随围压增加,裂纹贯通模式由拉破坏模式向剪破坏模式过渡.当围压为0时,试件在预制的两条裂纹端部分别生成外端翼裂纹和内端翼裂纹,内端翼裂纹与另一条预制裂纹搭接,导致岩桥贯通.在有围压条件下,试件出现反翼裂纹和次生共面裂纹,翼裂纹与另一条裂纹的次生共面裂纹搭接是岩桥贯通破坏的主要形式.2当岩桥倾角为135°时,原始裂纹尖端同时产生损伤,内外尖端翼裂纹同时起裂,随加载应力增加,翼裂纹不断向另一条原始裂纹方向扩展,最终扩展至另一条原始裂纹尖端,而两条外尖端翼型裂纹则扩展至试件端面,贯通整个试件后,最终导致岩石失稳破坏.
In order to study the mechanical failure characteristics of specimens with double cracks and provide a theoretical basis for evaluating the risk of water inrush from the floor, uniaxial and triaxial compression tests based on the MTS servo controlled testing machine were carried out by prefabricating double cracks in real rock specimens. RFPA numerical simulation was used to study the damage evolution and crack growth process of specimens with double cracks.The results show that the failure modes of specimens with double cracks have a significant confining pressure effect.With the increase of confining pressure, Mode transition.When the confining pressure is 0, the test specimen respectively produces the outer end flaw and the inner end flaw at the two prefabricated crack ends, and the inner end flaw overlaps with another prefabricated crack, resulting in the rock bridge going through. Under confining pressure, anti-wing cracks and secondary coplanar cracks appeared in the specimen, and the secondary coplanar crack overlapped with the other crack was the main form of rock-through failure.2 When the rockfill angle was 135 ° At the same time, the tip of the original crack is damaged at the same time and the tip and inner and outer tip flaws are simultaneously cracked. With the increase of the loading stress, the crack propagates in the direction of the other primary crack and finally extends to the tip of the other primary crack. Cracks extended to the end surface of the specimen, the specimen through the whole, resulting in unstable rock destruction.