稳定围岩为隧道爆破提供了重要的环境保障。为探究长距离隧道在周期性爆炸荷载下的围岩损伤特征与破裂机理，以下穿高速引水隧洞原位围岩及岩样为研究对象，借助SHPB（分离式霍普金森压杆）试验系统开展冲击劈裂试验，揭示了岩体力学行为和能量演化特征，并引入矿井巷道4D超高清成像技术，进一步分析了周期性爆炸荷载下隧道围岩的原位裂隙扩展机理。结果表明：①冲击劈裂下花岗岩和凝灰岩的劈裂应力-压缩应变曲线不同于通常冲击压缩“应力屈服”特征，而是具有“应力残余”特征，峰值应力和动力增长因子均呈正线性增长趋势；应变-时间曲线未出现通常冲击压缩“后期减小”变形特征，而是作为弹脆性材料表现出“后期稳定”变形特征。②岩体冲击能量-时间曲线历经“初始缓慢增长-快速线性增长-后期稳定”演化阶段，且同一冲击能级下岩体能量转化比率满足：反射能比率>耗散能比率>透射能比率；岩体损伤破坏整体表现出“中部劈裂+加载端部破碎→中部劈裂+加载端部破碎+半圆断裂→整体破碎”状态特征。③提出以“少域多测”与“多域少测”结合的窥孔成像试验，原位围岩孔壁裂隙扩展特征主要表现为“微裂纹发育→裂隙扩展→扩展放缓→停止延伸”演变阶段，未显现对围岩影响较大的破碎片脱落现象和继续向内延伸迹象。④综合山下顶管隧洞D1观测孔、山茶检修隧洞D2观测孔结果验证了良好的控界爆破效果，对现场爆破施工起到了显著的实际指导作用，同时取自隧道原位的岩样冲击劈裂结果为爆前钻孔与爆破方案设计提供了有效的理论依据和参考。

Stabilizing the surrounding rock provides an important environmental safeguard for tunnel blasting. To investigate the damage characteristics and rupture mechanism of the surrounding rock in long-distance tunnels under cyclic explosive loading, it takes the in-situ surrounding rock and rock samples of diversion tunnel underneath the highway as the study object. The impact splitting test was carried out with the SHPB test system. It revealed the mechanical behaviors and energy evolution characteristics of the rock body. It is also introduced the 4D ultra-high-definition imaging technology of the mine roadway to further analyze the in-situ fissure expansion mechanism of the tunnel peripheral rock under the cyclic explosive loading. The results show that: ① The splitting stress-strain curves of granite and tuff under impact splitting are different from the “stress yield” characteristic of impact compression. But they have the “residual stress” characteristics. The peak stress and dynamic growth factor DIF show a positive linear growth trend; The strain time curve does not exhibit the characteristic of “later reduction” deformation during impact compression. It exhibits the characteristic of “later stability” deformation as an elastic brittle material. ② The rock mass impacting energy - time curve undergoes an evolutionary stage of “initial slow growth - fast linear growth - later stable”. The energy conversion ratio of the rock mass under the same impact energy level satisfies the following conditions: reflected energy ratio > dissipated energy ratio > transmitted energy ratio; The overall damage and failure of the rock mass exhibits a state characteristic of “central splitting + loading end crushing → central splitting + loading end crushing + semi circular fracture → overall crushing”. ③ A peephole imaging test combining “less domains and more tests” and “more domains and less tests” is proposed. The crack propagation characteristics of the in-situ surrounding rock hole wall are mainly manifested in following evolutionary stage: “microcrack development → crack propagation → slow propagation → stop extension”. There is no significant phenomenon of fragmentation detachment and further inward extension. ④ The observation results of the D1 hole of the top pipe tunnel at the foot of the mountain and the D2 hole of the Shancha maintenance tunnel have verified the good boundary control blasting effect; The impact splitting results of rock samples taken from the original site of the tunnel provide an effective theoretical basis and reference for the design of pre blasting drilling and blasting schemes.