Directional fracturing of granite cylinder via nitromethane-based energetic materials driven by electrical wire explosion

Abstract

The combination of electrical wire explosion and low sensitivity energetic materials is an efficient and practical method to generate controllable strong pressure waves, which is a potential alternative to explosives in directional fracturing applications. In this paper, a new configuration of hybrid load is proposed to generate synchronized pressure waves for directional fracturing, with the advantages of lower energy storage and smaller blast-hole diameters. The pressure wave of hybrid load explosion is measured, and the explosion synchronicity of the two loads at the microsecond level is verified by self-illumination images. Then, two-hole granite cylinders are used to verify the feasibility of directional fracturing, and the results show that the double loads explosion formed directional fractures connecting the two holes and a horizontal failure plane. The fracturing process, including fracture initiation, propagation, and connection, is recorded with a high-speed camera and is reproduced in numerical simulation. Based on the experimental and numerical results, the fracture morphology is characterized as four areas, and the fracturing mechanism is analyzed.