Experimental research on optimum freezing temperature of sandy gravels in artificial ground freezing

• Published in: Environmental earth sciences 2024-03, Vol.83 (6), p.176, Article 176
• Main Authors: Wu, Wang, Yan, Qixiang, Qiu, Yunhui, Wang, Erli, Zhang, Chuan
• Format: Article
• Language: English
• Subjects: Biogeosciences; Building damage; Compression; Damage; Earth and Environmental Science; Earth Sciences; Energy efficiency; Environmental Science and Engineering; Experimental research; Freezing; Freezing temperatures; Frozen ground; Geochemistry; Geology; Gravel; Ground freezing; Ground ice; High temperature; Hydrology/Water Resources; Laboratory experimentation; Low temperature; Mechanical properties; Optimization; Original Article; Parameters; Principal components analysis; Shear tests; Soil; Soil freezing; Soil mechanics; Soil strength; Soil structure; Soil temperature; Temperature; Temperature distribution; Temperature fields; Terrestrial Pollution
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-023-11411-2

The control of freezing temperatures throughout the artificial ground freezing (AGF) process is always difficult. An overly high temperature of the circulating refrigerant may lead to insufficient frozen soil strength, while an overly low temperature may cause unnecessary energy waste, and even excessive pore ice may damage the soil structure and reduce the frozen soil strength. What's more, overly freezing may damage buildings on the surface. Therefore, it is of great significance to study the optimum freezing temperature (OFT), which is very important for better and more energy-efficient employment of the AGF method. In this paper, we use uniaxial compression and direct shear tests to obtain dynamic mechanical parameters in the soil freezing process. After the analysis of varying mechanical parameters by the entropy weight TOPSIS principal component analysis method, the results show that the interval range of OFT for saturated and unsaturated sandy gravel is [− 10 °C, − 15 °C] and [− 15 °C, − 20 °C], respectively. The findings indicate that, in the AGF method, a lower temperature is not always preferable. According to the results, constructive measures to optimize the temperature field distribution in the AGF method are proposed. The research results will contribute to the assessment of the safety and efficiency of AGF projects.