Abstract: During the mechanized construction of a connecting passage in a metro shield tunnel section, severe segment dislocation and sand-water gushing occurred. Rehabilitation work in small-section connecting passages is challenging. To address this, artificial freezing rehabilitation technology is proposed. First, the circular structure of the dislocated connecting passage is optimized into a straight wall crown structure. Second, a sealing wall is installed after backfilling the completed passage, and a freezing scheme using radial holes on one side is adopted. Third, drilling technology is improved using a high-precision inclinometer, and high-accuracy holes are created through azimuthal tracking and compensation. Shield segments and artificial structures are repaired and reinforced with densified planting bars and high-strength concrete pouring. Finally, temperature variations and deformation displacements during the freezing process are analyzed. The results indicate the following: (1) The development speed of the radial freezing curtain at the outer freezing wall is approximately 0.5 times that of a conventional connecting passage, whereas the inner side develops at a rate similar to that of a conventional passage. The inner side′s development speed is approximately twice that of the outer side. (2) Surface settlement is primarily concentrated around the freezing zone. Due to early grouting during drilling for sand and water control, the surface is raised by 3.7 mm; after withdrawing the shield from the jammed connecting passage, the induced surface settlement reaches 8 mm. (3) During the excavation and thaw settlement grouting periods, significant deformation occurs at the top of the connecting passage, with an uplift of 15 mm. This is attributed to reinforced soil above the passage, the continuous development of the freezing wall, and the influence of excavation structures.

Key words: connecting passage by mechanized construction, severe segment dislocation control, rehabilitation works, artificial freezing method