The Yujingshan tunnel of ChengduGuiyang
highspeed railway passes through a giant karst cave.
There is a largediameter unstable wedgeshaped body at the roof of the karst cave. To prevent the tunnel
roof from falling off and collapsing under this working condition, a joint
reinforcement of the roof with an expanded shell hollow grouting anchor rod and
a low prestressed fully bonded anchor cable is proposed. Furthermore, threedimensional numerical models of the surrounding rock with no roof
support, only bolt support, and combined support with bolts and anchor cables
are established using the finite element software. Meanwhile, the reinforcement
effect of the roof surrounding rock when the support is lagging is considered.
A comparative analysis is conducted on the variation rules of the anchor rod,
the axial force of the anchor cable, the displacement of the surrounding rock
and the plastic zone. Finally, an effective roof protection measure is found.
The results show the following: (1) The timely bolt and cable support can
effectively control the displacement of unstable surrounding rock and the
development of plastic zone, achieving good reinforcement effect. (2) The axial
force of anchor rod can be significantly reduced by applying anchor cable
structure in time, so as to avoid the failure of anchor rod due to overlarge axial force. (3) The application of expanded shell hollow
grouting anchor and low prestressed fully bonded anchor cable structure can
guarantee the safety of the Yujingshan tunnel.
ZHENG Jieyuan, WANG Yong, QING Weichen
. Roof Protection Technology for Giant Karst Cave in
Yujingshan Tunnel of ChengduGuiyang
HighSpeed Railway[J]. Tunnel Construction, 2021
, 41(S2)
: 413
-420
.
DOI: 10.3973/j.issn.2096-4498.2021.S2.053
