The coupling effect between high geostress state and
low strength surrounding rock increases the risk of tunnel instability. In
order to effectively control the large deformation of soft rock tunnels with
high geostress, the construction experience of nearly ten tunnels in soft rock
with high geostress in LijiangShangriLa,
YuxiMohan, and ChengduLanzhou
railways are summarized, the deformation characteristics and key control
technologies of these large deformation tunnels are expounded, and the effectiveness
of relevant technologies with monitoring data is rerified. The following
conclusions are made. (1)The reserved deformation is an important basis to
avoid the primary support from intruding into the structural limit of the
tunnel after a large surrounding rock deformation. (2) For the singletrack tunnel with a dominant horizontal tectonic stress, increasing
the curvature of the sidewall can effectively control the convergence of the
sidewall. (3) The doublelayer primary support together
with mixlength bolts can increase the stiffness of the
primary support and reduce the surrounding rock deformation. (4) The large
deformation can be controlled effectively and the cracking of secondary lining
can be reduced by installing the second lining at a proper time. (5) Quick
closing of the invert of the primary lining and keeping the distance between
the invert and the tunnel face at less than 20 m can play an effective role in
inhibiting convergence.
MA Dong
,
SUN Yi
,
WANG Wuxian
,
JIN Liujie
.
Key Technologies for Controlling Large Deformation of
Soft Rock Tunnels with High Geostress
[J]. Tunnel Construction, 2021
, 41(10)
: 1634
-1643
.
DOI: 10.3973/j.issn.2096-4498.2021.10.002
