In order to
study the weak position of local freezing area for Tjoint
of connection gallery bored by shield, and explore the influences of main
tunnel segments material, thermal conductivity of grouting body in the gap of
the tunnel opening, whether the soil is improved by grouting and the number of
frozen pipe ring on partial freezing. Based on a partial freezing strengthening
project of Tjoint of the connection gallery of the
Tianjin metro line 10, the distribution law of temperature field in the partial
freezing is analyzed by numerical simulation. The results reveal the following:
(1) At the tunnel opening, the freezing effect is better on the side of the
connection gallery than on the top and bottom. The steel segments extend further
toward the bottom of the main tunnel than toward the top, indicating a slightly
inferior freezing effect on the bottom half ring of the connection gallery
compared to the top half ring. (2) The primary factors affecting partial
freezing time are the material of the main tunnel segments and the thermal
conductivity of the grouting body in the gap of the tunnel opening. (3) When
the grouting body in the gap has a low thermal conductivity (0.93 W/(m·K)), the cooling energy cannot be transferred timely through the
grouting body to the main tunnel steel segments. Consequently, the cooling
energy in the soil behind the connection gallery transfers to distant soil
along the steel segments, resulting in a higher temperature of the soil near
the connection gallery, leading to a significantly longer freezing time
compared to cases with all reinforced concrete segments. (4) Increasing the
thermal conductivity of the grouting body in the gap improves the cooling
transfer efficiency, enhancing the freezing effect of the soil near the main
tunnel and reducing the freezing time. Elevating the thermal conductivity of
the grouting body in the gap from 0.93 to 1.8 W/(m·K) reduces the freezing time from 17
to 12 days under the condition that steel segments are partially used in the
main tunnel, and the required freezing time is 1 day shorter than that under
the condition that all reinforced concrete segments are used in the main
tunnel. It is concluded that the thermal conductivity of the grouting body in
the gap significantly affects the freezing time when steel segments are
partially used in the main tunnel.
CHENG Xuesong
,
XU Liankun
,
GENG Jia
,
LI Xiaofan
,
SONG Yanjie
,
LU Jiandong
,
WANG Shuxiong
. Partial Freezing Reinforcement Effect and Influencing
Factors of TJunction of Connection Gallery Bored by
Shield[J]. Tunnel Construction, 2024
, 44(1)
: 90
-99
.
DOI: 10.3973/j.issn.2096-4498.2024.01.007
