Repair Technology for Deformed Freezing Pipes in Cross Passages Through Confined Water-Rich Sand StrataRepair Technology for Deformed Freezing Pipes in Cross Passages Through Confined Water-Rich Sand Strata

To address the risk of secondary water and sand inrush induced by pipe-cutting repair of deformed freezing pipes in cross passages through confined water-rich sand strata, a repair method integrating structural tie restraint, locally reinforced artificial ground freezing, and grouped pipe cutting with sealing was proposed based on a sudden water and sand inrush case during freezing-hole construction in an intercity railway cross passage. The repair effect was verified through analytical calculation and field monitoring. The results show that based on back-analysis of field temperature measurements, the radius of the 0 °C isotherm after 21 days of active freezing was estimated at 0.52 m~0.56 m, with the brine supply temperature stabilized at approximately −28.5 °C and a supply-to-return temperature difference of 1.2 °C~1.8 °C satisfying the control requirements prior to pipe cutting. During pipe cutting, the maximum cumulative segment convergence, joint opening, and ground settlement were 2.8 mm, 0.8 mm, and 4.6 mm, respectively, all within the allowable limits; the pore pressure remained stable and controlled, and no blowout occurred. The proposed method can effectively reduce the secondary blowout risk during deformed freezing-pipe repair in confined water-rich sand strata using the existing freezing system.