Dynamic Characteristics of Hard-soft Interbedded Rock Mass under Impact Loading

The soft-hard interbedded structure represents a key contributor to rock mass anisotropy. This study examines the dynamic response of such formations under blasting loading through impact tests on six soft-hard interbedded configurations and four groups of rock-like specimens with varying hard rock ratios. Systematic analysis was conducted on dynamic mechanical properties, energy dissipation characteristics, and failure mechanisms in these composite rock systems. Results demonstrate that: (1) Specimen peak stress exhibits progressive enhancement with increasing hard rock content ratio, while displaying a marginal declining trend as layer quantity increases. (2) Increasing hard rock content reduces the energy reflection coefficient while enhancing both the energy transmission coefficient and absorption rate. Conversely, greater layer thickness increases energy reflection but diminishes the transmission and absorption coefficients. Notably, specimens impacted from the hard rock side demonstrate lower reflection coefficients but higher transmission coefficients and absorption rates compared to those impacted from the soft rock side. (3) As the hard rock content increases, the specimens exhibit progressively reduced overall damage severity, with the predominant failure mode transitioning from multi-directional conjugate shear fractures to tensile splitting. Conversely, increasing the number of layers markedly amplifies the intensity of specimen damage.