In a groundbreaking study that could reshape the future of underground construction, researchers have uncovered new insights into the behavior of pressurized frozen sand, offering a promising path toward more sustainable and efficient artificial ground freezing (AGF) techniques. The study, led by Zejin Lai from the School of Resources and Civil Engineering at Gannan Normal University, provides a fresh perspective on how pressurized freezing can enhance the stability of water-rich soils, a common challenge in geotechnical engineering.
The construction industry is under increasing pressure to reduce its carbon footprint, and conventional methods often fall short due to their reliance on high-emission materials. Artificial Ground Freezing presents a sustainable alternative, but its effectiveness hinges on a precise understanding of how frozen soil behaves under real-world conditions. Lai’s research delves into this very issue, focusing on the directional shear behavior of pressurized frozen saturated medium sand at -10°C.
Using a novel hollow cylinder apparatus, Lai and his team conducted systematic tests under varying mean principal stresses, with a fixed intermediate principal stress coefficient and principal stress direction. Their findings reveal that pressurized freezing creates a fundamentally different soil-ice composite compared to conventional unpressurized freezing. “We observed a linear strength increase described by the failure criterion qf = 1.17p + 3.77, which suggests that pressurized freezing can significantly enhance the stability of frozen soil without the pressure melting effects within the tested range,” Lai explained.
One of the most intriguing discoveries was the distinct brittle-to-ductile transition at a mean principal stress of approximately 4 MPa. Below this threshold, the soil exhibited localized shear bands, but above it, the failure mode shifted to homogeneous plastic flow. This transition is crucial for understanding the mechanical behavior of frozen soil under high-pressure conditions.
The implications of this research are far-reaching, particularly for the energy sector. AGF is widely used in the construction of underground facilities, such as tunnels and shafts, where stable ground conditions are paramount. By providing a more reliable and potentially less conservative frozen wall design, this study could lead to reduced energy consumption in AGF operations, making the process more cost-effective and environmentally friendly.
“Our findings enable more accurate predictions of frozen soil behavior, which can directly contribute to the design of safer and more efficient underground structures,” Lai noted. This enhanced understanding could pave the way for broader adoption of AGF in various geotechnical applications, supporting the construction industry’s transition toward sustainable underground development.
Published in the journal ‘Buildings’ (translated to English as ‘Buildings’), this research offers a compelling case for the integration of pressurized freezing techniques in modern construction practices. As the industry continues to seek innovative solutions to reduce its carbon footprint, Lai’s work provides valuable insights that could shape the future of underground engineering.
The study not only advances our mechanical understanding of frozen soil but also highlights the potential for pressurized freezing to become a cornerstone of low-carbon construction. By embracing these findings, the energy sector can move closer to achieving its sustainability goals, ensuring a more resilient and environmentally conscious approach to underground development.