During the main
tunnel construction at the inclined shaft site Nos. 8, 9, and 10 of the New
Wushaoling tunnel in phyllite and slate soft and broken rocks, many challenges
were faced, such as the frequent collapse of the tunnel face, primary support
cracking, and rock mass deformation and distortion. Accordingly, the data
analysis of geological prediction, monitoring measurement, surrounding rock
loose circle, construction stage, and support problems in drillandblast construction of the threebench method
is studied. The field test method is used to study advance reinforcement using
glass fiber anchor rods, advance large pipe shed support, twobench mechanical excavation method for reserving core soil by
cantilever excavator, reasonably reserved deformation, foot locking anchorage
enhancing the primary support, truss structure strengthening the primary
support longitudinal connection, radial grouting, and surrounding rock
consolidation. The fieldrelevant results show the
following. (1) The reserved core soil twobench largesection mechanical construction using a cantilever excavator is
feasible in soft rock tunnels with high ground stress. After using the advance
reinforcement and support structure methods, the stabilizing period of support
convergence is reduced by over a month.
The support structure′s accumulative deformation
is reduced by approximately half compared to the early phase, showing a
controllable deformation trend. (2) The
average linear overexcavation using a cantilever
excavator can be controlled within 15 cm, reducing the average overexcavation by approximately half of that by drillandblast methods (from 120% to 60%),
reducing the construction cycling time by 3 h, and improving the construction
efficiency from 25~35 m per month to 50~60 m per month. (3) Large deformation
control of soft rock with high ground stress should balance reasonable
construction methods, equipment, reserved deformation, and support structures
with specific deformation resistance.
CHEN Shanmin
,
WANG Quansheng
,
XIN Weike
,
JIA Dapeng
. Control Technology of Soft Rock Large Deformation in
New Wushaoling Tunnel Induced by Cantilever Excavator Construction[J]. Tunnel Construction, 2022
, 42(4)
: 720
-729
.
DOI: 10.3973/j.issn.2096-4498.2022.04.022
