Primary support deformation, inverted arch uplift, and
secondary lining collapse often occur during soft rock tunnel construction with
high ground stress. Therefore, countermeasures for large deformation of the
Daliangshan tunnel of the YunxianLincang expressway are
discussed. The deformation is characterized by follows: (1) large cumulative
deformation amount, high deformation rate, and long duration of primary support
deformation; (2) long section of uplift, and large uplift difference of
inverted arch greatly affected by water; (3) sudden crushing crack damage on
arch shoulder and crown after several months of secondary lining. The
geological conditions, failure characteristics, deformation characteristics,
and supplementary survey conclusions of the soft rock large deformation section
of the Daliangshan tunnel are comprehensively analyzed using theoretical
analysis, engineering analogy, numerical simulation, and onsite measurement methods. A plan for large deformation treatment,
including optimization of inverted arch curvature, primary support of doublelayer steel frame, secondary lining reinforcement, and limiting
anchor bolts around the tunnel, is designed, and construction and research on
the experimental section are conducted. The experimental results reveal the
following: (1) The cumulative construction of the experimental section is 323 m
with an average monthly footage of approximately 43 m. (2) Compared with the
original design, the support scheme for the experimental section reduces the
maximum peripheral convergence of the primary support from 1.4 to 0.30 m, the
maximum arch settlement from 0.80 to 0.52 m, and the daily average deformation
amount from 7 to 1－2 cm. (3) The large deformation of
the tunnel has been effectively controlled, with no cracking or falling of the
primary support, and no damage to the inverted arch and secondary lining. (4)
Based on monitoring data and onsite conditions, the
comprehensive support system scheme for the experimental section is analyzed
and summarized to be reasonable, and the key technologies for large deformation
treatment are generally successful.
ZHENG Yong, GUO Ping, WANG Lijun, CHEN Xingyu, DUAN Xiaobin, WANG Anmin
.
Countermeasures for Soft Rock Large Deformation of
Daliangshan Tunnel of YunxianLincang
Expressway With High Ground Stress
[J]. Tunnel Construction, 2023
, 43(S2)
: 437
-450
.
DOI: 10.3973/j.issn.2096-4498.2023.S2.048
