A case study is conducted on a doubletrack
metro shield tunnel crossing underneath railway subgrade in sandypebble strata. The deformation law of the subgrade is studied using
FLAC 3D numerical simulation based on field monitoring data analysis. The
applicable results of ground grouting by steeltube
prove the effectiveness of grouting reinforcement in controlling the subgrade
settlement. The main conclusions are drawn as follows: (1) The greater the
train speed and the smaller the shield burial depth, the greater the subgrade
settlement, whereas the influence of train speed on subgrade settlement is far
less than that of burial depth. (2) The approximate relationship among the
subgrade settlement, the burial depth, and the train speed is S=-26.54+0.85z-0.01v when the doubletrack metro shield undrcrosses the railway subgrade in sandypebble strata in Chengdu with a conventional clear distance of
approximately 7 m. Due to the twice disturbance of the shield tunneling, the
subgrade has experienced twice sudden drops in displacement, the displacement
and settlement curve shows a step shape, and the sensitivity of strata response
caused by the second disturbance is faster than that of the first one, as a
result, attention should be paid to the displacement caused by the second
disturbance. (3) The steel tubegrouting, as a highly
operable method for ground reinforcement, has a good reinforcement effect in
sandycobble strata in Chengdu. The settlement of
subgrade after grouting reinforcement is reduced from over 11 mm to 7 mm, which
ensures the smooth and successful shield tunneling.
MA Xiangfeng, WANG Lichuan, GONG Lun, CHEN Libao
.
Deformation and Grouting Reinforcement for Railway
Subgrade Crossed by a
DoubleTrack Metro Shield Tunnel in SandyCobble
Strata
[J]. Tunnel Construction, 2021
, 41(S1)
: 181
.
DOI: 10.3973/j.issn.2096-4498.2021.S1.023
