To find a solution for large deformation of soft
swelling rock with extremely high insitu stress in the Ningchan
tunnel in Qinghai province, laboratory test in conducted on the physicomechanical properties of rock samples. The realtime monitoring results of the tunnel are compared with those of the
Muzhailing tunnel, showing that the surrounding rock conditions of Ningchan
tunnel is worse and the construction difficulty is much higher. Phenomena such
as tunnel face collapse, large convergent deformation of surrounding rock, and
cracking of supporting structure occurred. The maximum crown settlement reaches
451.2 mm and the maximum horizontal convergence reaches 549.6 mm. In the test
construction section, the temporary invert was increased, the length of the
anchor rod was increased, the support stiffness was increased, the advance
support was strengthened, the rigidflexibility support
was adopted, and reserved deformation was increased. The monitoring results
show that the settlement and horizontal convergence of the crown are reduced by
about 100 mm on average, and the horizontal control effect is 3%~4% more than
that of the crown settlement, which is good in line with the numerical
simulation results, indicating a good control effect of the recommended methods
for Ningchan tunnel
GONG Jun, TANG Shuaiyao, ZHANG Danfeng, LI Zengyin, CHEN Zhimin, SUN Shengqi
. Construction Technology for Large Deformation Tunnel
in Soft Rock and Swelling Rock Interbedded Strata
with ExtremelyHigh Insitu
Stress[J]. Tunnel Construction, 2021
, 41(S2)
: 485
-493
.
DOI: 10.3973/j.issn.2096-4498.2021.S2.062
