Vibration velocity and frequency characteristics of surrounding rock of adjacent tunnel under blasting excavation.

The aim of this study is to improve the accuracy of response prediction and safety evaluation of blasting vibration of a deeply-buried tunnel group. For this purpose, the expression of frequency-domain and blasting vibration velocity spectra for the equivalent blasting load in multiple holes was derived through theoretical analysis, and propagation and attenuation of the primary frequency of blasting vibration of multiple cutting holes and caving holes in the infinite rock mass were explored. Response characteristics of vibration frequency spectra in rock surrounding of the adjacent tunnel induced by full-section blasting excavation of the tunnel under the high in situ stress were studied using the dynamic finite element method.

Distribution of cracks in an anchored cavern under blast load based on cohesive elements.

To explore the distribution of cracks in anchored caverns under the blast load, cohesive elements with zero thickness were employed to simulate crack propagation through numerical analysis based on a similar model test. Furthermore, the crack propagation process in anchored caverns under top explosion was analyzed. The crack propagation modes and distributions in anchored caverns with different dip angles fractures in the vault were thoroughly discussed.