When constructing a tunnel in expansive salt rock
strata, problems such as extensive lining cracking and inverted arch cracking
will be encountered. To ensure rapid construction and longterm
effective service of such a tunnel, the field investigation, numerical
simulation, and field measurement of the tunnel structure and construction
technology in an expansive salt rock stratum are analyzed. The following
results are obtained. (1) The expansion pressure caused by erosion of the
concrete by saline groundwater is the root cause of the original lining
cracking in the horseshoeshaped tunnel. (2) An
expansion pressure of 250 kPa significantly increases the deformation of the
surrounding rock but has a negligible effect on the longitudinal deformation of
the tunnel face. This reduces the maximum principal stress at the crown but
significantly increases the minimum principal stress at the inverted arch. (3)
Multilayer supports can play a positive role in restraining
the deformation of the surrounding rock and can significantly reduce the
longitudinal deformation of the tunnel face. However, it has no effect on the
maximum principal stress of the primary support. The absence of expansion
pressure causes the minimum principal stress to concentrate at the wall foot,
whereas the presence of this pressure reduces the minimum principal stress in
other parts. Considering the stability of the surrounding rock, supporting
force, and construction cost, a twobench method is
recommended for installing multilayer supports in
tunnels constructed in expansive salt rock strata. The field measurement shows
that the deformation degree of the surrounding rock is small and that the
lining is not cracked after installing three layers of concrete, two layers of
waterproof material, fullring grout, and water
blocking tenons in the bottom of the tunnel. Fitting the deformation of the
surrounding rock with the exponential function proves the accuracy of the
numerical calculation.
WANG Zhijie
,
LI Jinyi
,
ZHOU Feicong
,
JIANG Yifan
,
ZHOU Ping
,
DENG Yuhang
,
LIN Jiayong
. Structural System Optimization and Construction
Technology of Tunnel in Expansive Salt Rock Stratum for
ChinaLaos Railway[J]. Tunnel Construction, 2021
, 41(1)
: 16
-27
.
DOI: 10.3973/j.issn.2096-4498.2021.01.002
