Experimental study on static and dynamic mechanical properties of cracked rock after grouting reinforcement

The static and dynamic mechanical responses of rock mass after grouting reinforcement are important for evaluating the safety and stability of rock engineering. In order to study the mechanical characteristics of grouting-reinforced rock under static and cyclic impact loads,the failure mechanism and damage evolution model of red sandstone samples of different grouting types were studied using the drop hammer impact test device. The test results show that specimens grouted by cement show poor reinforcement effect due to the low bonding performance and strength of the cement,while that resin grouting material can effectively improve the stress concentration caused by cracks and obtain a good reinforcement effect due to its high strength,toughness and good coordination with the rock. The maximum tension strain at the middle position of the cement grouting sample first increases rapidly and suddenly changes when the load reaches the peak value of the cement cracking load,while the strain changes of the specimens grouted by resin are smooth and there is no obvious mutation. All specimens,whether or not they are grouted,will be destroyed immediately when the impact energy is large enough. For both resin grouting specimens and un-cracked specimens,there is a clear double logarithmic linear relationship between the impact energy and the impact life,and the specimen will be damaged when the impact cumulative residual strain reaches the difference between the static peak strain and the dynamic peak strain. The damage evolution curve presenting an obvious three-stage change was obtained and verified by experiments of different grouting types and different impact energy. The damage evolution can better simulate the damage accumulation during the impact process. © 2020, Science Press. All right reserved.