Compared to conventionalconnecting
galleries, overlappingconnecting galleries present
unique challenges. These include larger frozen volumes, longer excavation and construction
times, and more complex freezing hole layouts. To safely and efficiently
construct overlappingconnecting galleries in waterrich sandy strata, a freezing scheme is designed based on their
structural forms. First, soil samples are collected from the Hesongjie station
site of phase II of the Harbin metro line 3. Physicomechanical
tests are then conducted at the temperature of －10 ℃. The results reveal a uniaxial compressive strength of 3.53 MPa for
silty clay. Then, the thickness of the frozen walls at an average temperature
of －10 ℃ is determined. The top
and sidewalls are found to be 3.0 m thick, while the collecting well is
estimated to be 4.0 m thick. Numerical calculation results illustrate that both
the strength and displacement indicators of the frozen walls meet the safety
requirements. Moreover, freezing holes are arranged according to the thickness
of the frozen walls. A reinforcement method of "vertical freezing on
ground and horizontal freezing in the tunnel" is also proposed. The implementation
of pressurerelief holes on the ground and horizontal
pressurerelief holes in the tunnel effectively control
frost heave, limiting it to a maximum of 8.59 mm. This reduces the impact on
the surrounding environment. In conclusion, the proposed method ensures the
stability of the excavation face and controls frost heave within the allowable
range.
SHI Limin
,
YE Yuxi
,
DU Youchao
,
DONG Shizhuo
. Freezing Method Design for OverlappingConnecting Galleries in WaterRich Sandy
Stratum[J]. Tunnel Construction, 2024
, 44(1)
: 148
-154
.
DOI: 10.3973/j.issn.2096-4498.2024.01.013
