Study on Vertical Freezing Technology Applied in the Emergency Remediation of Foshan Metro Line 2 Project

Based on the emergency remediation case of applying the vertical freezing technology in the right line of Huyong station - Lvdaohu station section of Foshan metro line 2, the numerical modeling and monitoring data analysis methods are used to systematically research the development law and application effects of the vertical frozen wall in the water-rich sand layer. The results show that it is completely feasible to isolate the hydraulic connection between undamaged and damaged tunnel sections with the vertical freezing technology. When the target ground are frozen with multiple rows of freeze pipes, the temperature of surrounding ground will influence the development of frozen walls, and the peripheral cooling rate of the frozen wall is obviously slower than that of inside the frozen wall.During freezing construction, to improve the peripheral development speed of the frozen wall, the refrigerating powers of the peripheral refrigerators should be increased and the refrigerator numbers of peripheral freezing holes can be added when necessary. It is recommended that temperature monitoring holes should be installed between the adjacent freezing pipes of the outmost row of frozen wall (the weakest point), to accurately determine the development quality and closure time of the frozen body.