Experimental study on blast wave propagation in coral reef limestone

Abstract

[Objective] The aim is to address the difficulties in conducting large-scale explosion impact tests on coral reef limestone due to the small core size and strong heterogeneity, as well as the challenges in obtaining the propagation patterns of blast waves. [Methods] Based on the small-scale explosion simulation technology using the fine electromagnetic measurement method for blast waves, a combined design of the center-detonated miniature spherical explosive and the circular electromagnetic particle velocimeter was adopted to precisely measure the time-history curves of blast wave particle velocity in reef limestone at scaled distances of $20 \sim 80 \mathrm{~m} / \mathrm{kt}^{\frac{1}{3}}$ The result showed that the blast waves in reef limestone progressively degraded from strong intermittent shock waves into continuous compression waves, with gradually increasing duration and decreasing peak particle velocity. Within the test range, the attenuation indices of the peak stress and peak particle specific displacement of the blast waves in reef limestone were 1.89 and 1.39, respectively. Explosion-induced cavity formation in the reef limestone was obvious, but the natural pore and fracture systems significantly attenuated blast waves, inhibiting the development and propagation of explosion-induced fractures. After the explosion, the reef limestone was mainly characterized by deformation and compaction of the pores and the extension of natural fractures. [Conclusion] The research findings reveal the explosion-induced damage effects and the propagation attenuation patterns of peak stress and peak specific displacement in reef limestone, and propose a calculation formula for blast wave attenuation, providing experimental support for the analysis of the explosion impact effects in reef limestone.

Keywords

reef limestone / electromagnetic method / miniature spherical explosive / blast wave / attenuation coefficient / damage effect / influencing factors / explosion impact effects