Influence of Joint Angles on Stress Wave Propagation Behavior of Columnar Charges in Gradient Materials

The propagation of blast-induced stress waves in gradient-strength rock masses is strongly influenced by variations in material strength and the presence of jointed weak planes, resulting in highly heterogeneous responses that critically affect blasting efficiency and the stability of surrounding rock. To clarify these mechanisms, a physical model incorporating gradient materials and jointed weak planes was developed, and a series of experiments were conducted using a digital image correlation system to analyze stress wave transmission and reflection. Finite element simulations were subsequently performed to validate the experimental results, and the outcomes exhibited good consistency. The findings reveal that stress waves in gradient materials display distinct stratification effects: regions with higher elastic modulus exhibit weaker strain responses and more pronounced gradient distributions. In addition, jointed weak planes significantly modify transmission and reflection patterns, generating abrupt stress peaks and partially retarding peak attenuation. The close agreement between experimental observations and numerical simulations confirms the reliability of the proposed approach. Overall, this study provides robust experimental evidence and theoretical insights for optimizing blasting parameters and enhancing rock mass stability under complex geological conditions.