In order to solve the
problem for safe implementation of C-shaped
connecting gallery in the overlapping section of metro shield tunneling in
complex environments and rich water sand layers, a segmented hidden excavation
method with "first lower, then upper, and finally middle" as the
construction process and a matching time-based and
regional freezing auxiliary method is adopted. First, the thickness of the
frozen wall and other main freezing parameters for each part are determined,
and tests are conducted on the frozen soil to obtain the strength indicators
for each layer of frozen soil. Strength verification is conducted on the frozen
wall, and the verification results meet the safety factor requirements. Second,
the ground vertical and horizontal freezing pipes inside the tunnel are
reasonably arranged, and technical measures are used to reduce the impact of
cross freezing and frost heave, ensuring the freezing effect. Then, preembedded grouting pipes are used in various parts of the connecting
channel and thawing and settlement grouting are carried out from bottom to top,
using the way of "multi-point, small amount,
multiple times, and even" according to the thawing process, to control
structural and geological settlement. Finally, the status of frozen walls,
structures, ground, and surrounding environment during construction is
monitored, providing guidance for construction correction. The results show
that: by using the proposed method to construct the C-shaped
connecting gallery, high strength of the frozen wall, good water sealing
performance, small frost heave and thaw settlement, minimal structural
deformation and impact on the surrounding environment can be achieved.
WANG Qingli
. Design and Engineering
Practice of C-Shaped Connecting Gallery for
Frozen Excavation Method in Rich Water Sand Layer[J]. Tunnel Construction, 2024
, 44(S1)
: 387
-395
.
DOI: 10.3973/j.issn.2096-4498.2024.S1.042
