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在深部开挖工程中,深部岩石往往经历“三轴高应力+开挖卸荷+动力扰动”的全应力过程.为了研究围压卸荷对深部预应力岩石的动态破坏特征的影响,采用改进的分离式霍普金森压杆对红砂岩进行了一系列三轴卸荷动态压缩试验,还进行了单轴预应力冲击压缩试验(不考虑围压卸荷效应).结果表明,红砂岩的动态抗压强度表现出明显的应变率效应.在应变率近似相等的情况下,三轴卸荷动态压缩试验中岩石的动态强度小于单轴预应力冲击压缩试验中岩石的动态强度.围压卸荷造成明显的强度弱化效应,并采用动态强度弱化因子(DSWF)量化强度弱化程度.在同一个应力路径下,岩石的应变率和入射能呈对数关系;而在入射能相同时,卸荷会导致预应力岩石有着更高的应变率.分析了试样的破坏模式,发现卸荷对试样破坏模式的影响并不显著.此外,讨论了围压卸荷对剪切强度参数(内聚力和摩擦角)的影响.在入射能相同时,发生卸荷后的预应力岩石更容易发生破坏.因此,在深部岩石工程开挖设计中应考虑卸荷对岩石力学特性的影响.“,”In the process of deep projects excavation, deep rock often experiences a full stress process from high stress to unloading and then to impact disturbance failure. To study the dynamic characteristics of three-dimensional high stressed red sandstone subjected to unloading and impact loads, impact compression tests were conducted on red sandstone under confining pressure unloading conditions using a modified split Hopkinson pressure bar. Impact disturbance tests of uniaxial pre-stressed rock were also conducted (without considering confining pressure unloading effect). The results demonstrate that the impact compression strength of red sandstone shows an obvious strain rate effect. With an approximately equal strain rate, the dynamic strength of red sandstone under confining unloading conditions is less than that in the uniaxial pre-stressed impact compression test. Confining pressure unloading produces a strength-weakening effect, and the dynamic strength weakening factor (DSWF) is also defined. The results also indicate that the strain rate of the rock and the incident energy change in a logarithmic relation. With similar incident energies, unloading results in a higher strain rate in pre-stressed rock. According to the experimental analysis, unloading does not affect the failure mode, but reduces the dynamic strength of pre-stressed rock. The influence of confining pressure unloading on the shear strength parameters (cohesion and friction angle) is discussed. Under the same external energy impact compression, pre-stressed rock subjected to unloading is more likely to be destroyed. Thus, the effect of unloading on the rock mechanical characteristics should be considered in deep rock project excavation design.