Fractal analysis for the blast-induced damage in rock masses with one free boundary

Abstract

The research on blasting damage of medium has important engineering significance, wherein one of the main factors affecting the blasting effect of the medium is the free boundary of the medium. In this article, the blasting damage of media with one free boundary is studied and the damage evaluation based on fractal theory is carried out. Firstly, an experimental device is designed to simulate the state of the medium’s one free boundary. The distance between blasthole and the free boundary is the only variable considered in the experimental investigation. The fractal theory is used to analyze the fractal damage of the medium caused by the explosion, and MATLAB is used to extract three characteristic parameters (damage depth, damage width, and damage zone) of the binary image after the explosion. Finally, LS-DYNA is used to build a 2D plane strain model with the same size and boundary conditions, which simulates the damage evolution process of medium under a single free boundary blasting pattern. The fractal theory is then used to evaluate the fractal damage observed in the numerical simulation results. The experimental results and numerical simulation results of blasting fractal damage of one free boundary medium are in good agreement. The blasting fractal damage grows initially and subsequently decreases as the distance between the blasthole and the free boundary increases. Thus, the distance between blasthole and free boundary affects the efficiency of blasting energy destroying medium and the blasting failure pattern.