To better understand the rock fragmentation mechanism and optimize cutter design and selection for rock excavation by TBM, a set of three-dimensional indentation tests was conducted with different rock and cutter types. Acoustic emission (AE) monitoring technique was employed to capture the information of the rock damage evolution real-timely. It is found that the penetration by using the constant cross section (CCS) cutter tends to induce inconspicuous rock chips formation before the sudden occurrence of the macrocrack, but that by using the V-type cutter tends to induce gradual rock fragmentation accompanied by the multiple local rock chips formation and the sawtooth force-penetration curve. Meanwhile, rock fragmentation models for CCS and V-type cutters were compared, and the spatio-temporal evolution of AE events was quantitatively analyzed to reflect the rock damage zone development process. Results indicate that the V-type cutter has greater penetration ability and the CCS cutter can cause larger unit damage zone radius. Microscopic observation by using the scanning electron microscope (SEM) reveals that the fracture mechanism for the crushed zone of rock is mainly shear type and that for the major crack is tensile type. It does not matter with rock types or cutter types.

中文翻译：

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圆盘刀具穿透作用下岩石破碎的力学和声发射响应

为了更好地了解碎石机理，并优化TBM开挖岩石的刀具设计和选择，对不同类型的岩石和刀具进行了一套三维压痕测试。采用声发射（AE）监测技术实时捕获岩石损伤演化信息。结果发现，使用等截面刀具（CCS）进行的钻进趋向于在大裂纹突然发生之前引起不明显的碎屑形成，但是使用V型刀具趋于引起岩石的碎裂并伴有多次破裂。局部岩屑形成及锯齿力穿透曲线。同时，比较了CCS和V型刀具的岩石破碎模型，定量分析了声发射事件的时空演化，以反映岩石破坏带的发育过程。结果表明，V型刀具具有更大的穿透能力，而CCS刀具可引起较大的单元损坏区域半径。扫描电镜观察表明，岩石破碎区的断裂机理主要为剪切型，主要裂纹的断裂机理为拉伸型。与岩石类型或切割器类型无关。扫描电镜观察表明，岩石破碎区的断裂机理主要为剪切型，主要裂纹的断裂机理为拉伸型。与岩石类型或切割器类型无关。扫描电镜观察表明，岩石破碎区的断裂机理主要为剪切型，主要裂纹的断裂机理为拉伸型。与岩石类型或切割器类型无关。