Investigating the role of the structural and mechanical properties of rock in dynamic design of caverns using Split Hopkinson Pressure Bar device

The importance of caverns makes it necessary to create underground structures in the rocky environment. However, in designing these structures the depth of the overburden is mostly considered, and the dynamic mechanical behavior of rocks in dynamic loading is less taken into account. This is while the mechanical properties of rocks such as compressive strengths is also changed due to the strain rate and confining stress. In this paper, the role of rock dynamics in the framework of the safe design of caverns was considered. In the following, the effect of microstructure properties on the mechanical behavior of rock in quasi-static and dynamic loading was studied, and experiments suggested by ISRM were conducted. The rate of compressive strength increase by changing the loading type, strain rate and confining stress in two marble samples with different microstructures was investigated. The rock strength increase factor with confining stress for marbles at a depth of 85 m was also determined being 1.15 in a quasi-static loading, and 1.65 in dynamic loading, which clarifies that there is a direct relationship between rock strength increase factor and the depth of deployment when strain rate is applied.