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.
YAN Chao
,
YANG Ping
,
ZHANG Ting
.
Freezing Rehabilitation Technology for Severe Segment Dislocation in Connecting Passages by Mechanized Methods
[J]. Tunnel Construction, 2025
, 45(2)
: 392
-401
.
DOI: 10.3973/j.issn.2096-4498.2025.02.015
