Abstract The instability of shotcreted structures, e.g., the underground tunnels after shotcreting, often results from the tensile failure of the rock-concrete interface. However, the understanding of the properties, e.g., the failure mode and the failure mechanism, of the rock-concrete interface against tension, in particular dynamic tension, is still at its infancy. In this study, static and dynamic Brazilian disc tests were conducted to investigate the effect of rock type, concrete strength, concrete admixture and interface roughness on the adhesive properties of rock-concrete specimens from macro and micro views with the combination of high-speed photography, digital image correlation, laser scanning and SEM techniques. The results showed that rock type, concrete strength and admixture determine the nominal tensile strength of rock-concrete interface through changing the adhesive force between rock and concrete. Interfacial adhesive properties are not dependent on rock strength but on rock physical properties, e.g., constituent grains. Increasing concrete strength as well as adding concrete admixture could improve the adhesive force between rock and concrete except for adding basalt fibre under dynamic tension. Interface roughness determines the bearing capacity of rock-concrete specimen through influencing the mechanical interaction of the interface. The nominal tensile strength of rock-concrete specimen increases with interface roughness degree. The failure mode of rock-concrete specimen depends on the interface type and sawtooth dip angle, and the bearing capacity of rock-concrete specimens varies with failure mode. In addition, from a micro-view, the compactness degree of the failure surface and the content of adhesive materials such as calcium silicate hydrate and hydroxide carbon determine the adhesive behaviour between rock and concrete. The findings in this study could facilitate better understanding of the adhesive behaviour of rock-concrete structures and are of great engineering significance to the maintenance and reinforcement of shotcreted structures, in particular tunnels after shotcreting.

中文翻译：

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基体性质和界面粗糙度对岩石-喷射混凝土界面静态和动态拉伸行为的宏观和微观影响

摘要 喷射混凝土结构的失稳，例如喷射混凝土后的地下隧道，往往是由岩石-混凝土界面的拉伸破坏引起的。然而，对岩石-混凝土界面抗拉力，特别是动态拉力的破坏模式和破坏机制等特性的理解仍处于起步阶段。本研究通过静态和动态巴西圆盘试验，结合高速摄影，从宏观和微观角度研究岩石类型、混凝土强度、混凝土外加剂和界面粗糙度对岩-混凝土试件粘结性能的影响。 、数字图像相关、激光扫描和 SEM 技术。结果表明，岩石类型，混凝土强度和外加剂通过改变岩石与混凝土之间的粘附力来决定岩石-混凝土界面的标称抗拉强度。界面粘合特性不依赖于岩石强度，而是依赖于岩石物理特性，例如组成颗粒。增加混凝土强度和添加混凝土外加剂可以提高岩石与混凝土之间的粘附力，除了在动态张力下添加玄武岩纤维。界面粗糙度通过影响界面的力学相互作用来决定岩石-混凝土试件的承载能力。岩石-混凝土试件的名义抗拉强度随界面粗糙度的增加而增加。岩石混凝土试件的破坏模式取决于界面类型和锯齿倾角，岩石混凝土试件的承载力随破坏模式而变化。此外，从微观上看，破坏面的密实程度和水合硅酸钙、氢氧化碳等胶粘材料的含量决定了岩石与混凝土的胶粘行为。本研究的发现有助于更好地理解岩石-混凝土结构的粘附行为，对喷射混凝土结构的维护和加固，特别是喷射混凝土后的隧道具有重要的工程意义。