Based on the shallowburied
mined doublearch tunnel project applied in parking lot
of Xi′an Metro Line No. 5, the deformation characteristics of doublearch
metro tunnel in loess area are studied. The variation rules of surface
settlement, lining deformation of new tunnel and hance convergence of superadjacent existing tunnel are analyzed through field monitoring data.
The results show that: (1) In the construction, the maximum surface settlement
is 19.66 mm and the maximum settlement rate is 2.31 mm/d, both of which are
less than the construction control limit. (2) For ultrashallow buried tunnels, influencing factors such as construction
uncertainty, soil heterogeneity, soil anisotropy, surface random load, etc.
will obviously affect the shape of the surface settlement curves, which may
make the Peck formula have a large deviation from the predicted results of the
surface settlement. (3) When the surface settlement reaches a stable state, the
distance between the tunnel surface and the monitored section is obviously more
than 5 times of the tunnel diameter, while the primary support deformation rate
is faster, and the corresponding distance is basically 3~5 times of the tunnel
diameter when the surface settlement reaches a stable state. (4) Due to the
barrier effect of the middle pilot hole, the effect of the construction of the
back tunnel on the stress variation and convergent deformation of the primary
support of the first tunnel is not obvious. (5) When the distance between the
tunnel face and the monitored section is more than 2 times of the tunnel
diameter, the convergence of the hance of the existing tunnel basically tends
to be stable, and the final convergence value of the hance at all monitored
sections is basically within 4 mm.
GUO Hongtao
,
MA Jiakuan
,
DAI Jiabao
,
REN Xiang
,
LIU Jiaqi
. Research on Deformation Characteristics of Shallowburied
MinedDoublearch Metro Tunnel
in Loess Area: a Case Study on Parking Lot Entrance
and Exit Line Project of Xi′an Metro Line No. 5[J]. Tunnel Construction, 2020
, 40(10)
: 1417
-1425
.
DOI: 10.3973/j.issn.2096-4498.2020.10.004
