Application of Liquid-Oxygen Phase Change Gas Expansion Technology in Tunnel Excavation

This study aims to address the challenge of rapid tunnel excavation without the use of explosive. A new oxygen expansion rock breaking technology suitable for general tunnel excavation such as cutting, expanding, auxiliary and peripheral holes is explored, researched, and summarized. The drilling and blasting parameters optimized for tunnel excavation are also provided in detail. The experimental study section consists of granite with a compressive strength ranging from 90 to 100 MPa, developed cleavage cracks, and average blastability. Through field tests and continuous improvement, an average cycle footage of 2.5 m per two-day cycle is achieved for a tunnel area of approximately 65 m², meeting the requirements for rapid excavation when explosives cannot be used. The research demonstrates that the new gas expansion rock-breaking technology can effectively excavate tunnels in hard rock masses. It offers advantages such as safe operation, high efficiency in rock breaking, no involvement with civil explosives or dangerous chemicals used in explosive production, absence of explosion shock waves and low vibration amplitude. This technology provides a solution to situations where civil explosives are prohibited due to complex environmental conditions or slow progress using mechanical methods.