Precisely understanding the dynamic mechanical properties and failure modes of rocks subjected to true triaxial stress state (σ₁ > σ₂ > σ₃, where σ₁, σ₂, and σ₃ are the major principal stress, intermediate principal stress, and minor principal stress, respectively) is essential to the safety of underground engineering. However, in the laboratory, it is difficult to maintain the constant true triaxial stress state of rocks during the dynamic testing process. Herein, a numerical servo triaxial Hopkinson bar (NSTHB) was developed to study the dynamic responses of rocks confronted with a true triaxial stress state, in which lateral stresses can maintain constant. The results indicate that the dynamic strength and elastic modulus of rocks increase with the rise of intermediate principal stress σ₂, while the dynamic elastic modulus is independent of the dynamic strain rate. Simulated acoustic emission distributions indicate that the intermediate principal stress σ₂ dramatically affects dynamic failure modes of triaxial confined rocks. As σ₂ increases, the failure pattern switches from a single diagonal shear zone into two parallel shear zones with a small slant. Moreover, a recent triaxial Hopkinson bar experimental system using three bar pairs is also numerically established, and the measuring discrepancies are identified between the two numerical bar systems. The proposed NSTHB system provides a controllable tool for studying the dynamic triaxial behavior of rocks.

准确理解岩石在真三轴应力状态下的动态力学特性和破坏模式（σ ₁  >  σ ₂  >  σ ₃，其中σ ₁、σ ₂和σ ₃分别是大主应力、中间主应力和小主应力）对地下工程的安全至关重要。然而，在实验室中，动态测试过程中很难保持岩石的真三轴应力状态不变。在此，开发了数值伺服三轴霍普金森杆 (NSTHB) 来研究岩石在真实三轴应力状态下的动态响应，其中侧应力可以保持恒定。结果表明，岩石的动态强度和弹性模量随着中间主应力σ _{2 的}增加而增加，而动态弹性模量与动态应变率无关。模拟的声发射分布表明，中间主应力σ ₂显着影响三轴约束岩石的动态破坏模式。随着σ _{2 的}增加，破坏模式从单个对角剪切区切换到两个具有小倾斜度的平行剪切区。此外，最近还建立了一个使用三个杆对的三轴霍普金森杆实验系统，并确定了两个数字杆系统之间的测量差异。所提出的 NSTHB 系统为研究岩石的动态三轴行为提供了一个可控的工具。