Minimum safety distance of adjacent explosive storage caves in class IV wall rocks

Abstract

To determine the minimum safety distance between explosive storage caves in Class IV wall rocks, a developed refined finite element (FE) model was established on the basis of fully verifying a constitutive model for high strain rate materials. The FE model was subsequently validated by comparing the calculated minimum safety distances with those specified by the relevant codes for Class I, II, and III wall rocks. Based on the validated model, the propagation process of shockwaves and blast-induced stress waves in the explosive storage cave interior, cave lining, and surrounding rocks were analyzed, and the damage characteristics of the adjacent storage in different surrounding rock grades were obtained. In addition, a method for calculating the minimum safety distance of adjacent explosive storage caves based on the residual bearing capacity factor of the lining structure was developed. The calculation results indicated that when an explosion occurred inside a cave, the detonation products and shockwaves could not be completely separated before reaching the lining structure. The blast load on the surface of the structure was significantly higher than that calculated from the ground explosion. Moreover, the critical scaled distance of an explosion between caves was approximately equal to that for wall rocks of the same class. The residual lining bearing capacity, which characterizes the damage and destruction of the adjacent cave structure, was recognized as a crucial indicator of the inter-cave minimum safety distance. Analytical results indicated that the critical scaled distance for explosive storage caves in Class IV wall rocks was approximately 0.993 m/kg^1/3 and that the minimum safety distance between two caves was 49 m.