In the relentless pursuit of efficient and cost-effective tunneling solutions, a groundbreaking study led by Anxin Wang from the College of Energy Science and Engineering at Henan Polytechnic University has shed new light on the optimal use of high-pressure water jets to assist in rock breaking. Published in the journal ‘Meitan kexue jishu’ (which translates to ‘Coal Science and Technology’), this research promises to revolutionize the way we approach hard rock tunneling, particularly in the energy sector.
Tunneling through ultra-high strength rock has long been a formidable challenge, plagued by difficulties in penetration, significant tool loss, and low efficiency. Traditional methods often fall short, but Wang’s research introduces a promising alternative: high-pressure water jets. “The arrangement of water jet and cutter would directly affect the force of cutter and the specific energy of rock breaking,” Wang explains, highlighting the critical nature of this study.
Using a discrete element model based on the Thiessen polygon algorithm, Wang and his team employed Particle Flow Code (PFC) to simulate the rock-breaking process. Their findings reveal that the bottom of the notch is a stress concentration area, and the presence of a pre-cut slit influences crack expansion, directing it towards the slit’s bottom. “The increase of pre-cut slit length can reduce the hob load,” Wang notes, “but the effect is gradually weakened with the increase in length of the pre-cut slit.”
One of the most significant discoveries is the optimal impact angle of the water jet. The study found that the specific energy of rock breaking follows a “V” shaped curve as the impact angle increases, with the best rock-breaking effect achieved at a 75° angle. This finding is crucial for improving the tool life of Tunnel Boring Machines (TBMs), a critical piece of equipment in the energy sector.
The commercial implications of this research are substantial. By optimizing the water jet impact angle, energy companies can enhance the efficiency and longevity of their tunneling equipment, leading to significant cost savings and improved project timelines. “The reasonable selection of water jet impact angle can contribute to improving the TBM tool life,” Wang states, underscoring the practical applications of this research.
As the energy sector continues to push the boundaries of exploration and extraction, innovations like those presented in Wang’s study will be instrumental in overcoming the technical challenges of hard rock tunneling. This research not only provides a theoretical reference for the arrangement of water jet systems and nozzle angles in TBM cutter heads but also paves the way for future advancements in the field.
In an industry where every percentage point of efficiency gain translates to substantial financial benefits, Wang’s work stands as a testament to the power of scientific inquiry and its potential to drive commercial success. As we look to the future, the insights gleaned from this study will undoubtedly shape the development of more effective and efficient tunneling technologies, ensuring that the energy sector can meet the demands of an ever-growing global population.