The complicated working procedure and frequent stress
transformation at the intersection between main and auxiliary tunnels are big
challenges in the traditional roof-lifting method. To improve the
safety of the roof-lifting construction of the
auxiliary tunnel entering the main tunnel in soft stratum and to effectively
control the primary supporting deformation at the stress concentration
position, a case study is conducted on the construction of Zhaotong tunnel
inclined shaft No. 2 entering the main tunnel of Chongqing-Kunming high-speed railway. The roof-lifting technology of the upper connecting hole + portal frame
method is studied based on the full analysis of the geological characteristics
of expansive soil in the inclined shaft section. An independent upper guide
tunnel is set behind the intersection between the auxiliary and main tunnels to
excavate the main tunnel crown. Meanwhile, multiple working faces are performed
synchronously with the roof of the main hole and the lining of the inclined
shaft. Additionally, the application of the close-row
gantry roof-lifting technology can effectively fit the
excavation contour of the main tunnel, realizing a safe and fast roof-lifting operation. The construction results show that the
interaction effect of the auxiliary and main tunnels can be minimized,
obtaining a synchronous, safe, and fast construction.
ZHANG Hongda
. Construction Technology of Roof Lifting Using Portal
Frame Method of Auxiliary Tunnel Entering Main Tunnel in Soft Stratum[J]. Tunnel Construction, 2021
, 41(12)
: 2150
-2156
.
DOI: 10.3973/j.issn.2096-4498.2021.12.016
