Mechanical Properties of the Combination of Surrounding Rock and Primary Support under Impacting Load.

The SHPB experimental device was adopted to carry out the uniaxial impact tests in studying the failure characteristics of the combination of surrounding rocks and primary support for the tunnel, so as to explore the key factors affecting its dynamic strength and deforming properties. To simplify the practice model of the tunnel construction, the specimens combined by the surrounding rock and primary support were simulated by the concentric annular sandstone and cement mortar in this paper. The results indicate that the thickness of the primary support, the thickness of the surrounding rock and the proportion of the thickness of the primary support are the key factors affecting the dynamic strength of the combination of the surrounding rock and the primary support. The influence of dynamic loads on tunnel construction can be weakened by adjusting the above three factors, so that to improve the supporting capacity. The research has a significant reference for the designing of tunnel engineering under complex loads. [ABSTRACT FROM AUTHOR]