To guarantee the safe shield tunneling of overlapping
tunnel with ultrasmall clear distance in waterrich sandy stratum, a case study is conducted on the tunnel between
Taikang road station to Erqi square station of Zhengzhou metro line No. 3.
Then, the safety control techniques for overlapping tunnel are proposed
according to complex and severe conditions such as the limited site conditions,
waterrich siltyfine sandy
stratum, ultrasmall clear distance, and the
superposition of secondary settlement. The results show the following: (1) The
horizontal platetype freezing wall for freezing
reinforcement and short steel sleeve launching technology are adopted to
improve the stability of the end soil and to reduce the risk of water leakage
of shield launching. (2) To ensure strength of the soil layer and reduce the
secondary settlement, the middle layer in the lower tunnel is grouted first,
and the middle layer in the upper tunnel is grouted after tunneling. (3) Shield
driving parameters are reasonably controlled, and synchronous grouting and
monitoring inside and outside the tunnel are strengthened. (4) The lower tunnel
is supported by roller trolley when tunneling in the upper tunnel, and the
trolley is moved synchronously with the upper tunnel shield tunneling to ensure
the continuous support force. (5) The analytical results of monitoring data of
the tunneling of the lower tunnel and the superimposed tunneling of the upper
tunnel show that the maximum ground settlement, pipeline settlement, and tunnel
deformation are 14.74 mm, 2.44 mm and 3.14 mm respectively, which can control
the ground, pipeline, and tunnel deformation within the safe range and achieve
good results.
AN Jianyong, LEI Haibo, YIN Hongwei, LIU Zeliang, JIN Xin, YANG Ning, GUAN Xiaoming
. Safety Control Technology for UltraSmall
Clear Distance Overlapping Shield Tunnel Construction
in WaterRich Sandy Stratum[J]. Tunnel Construction, 2021
, 41(S2)
: 503
-511
.
DOI: 10.3973/j.issn.2096-4498.2021.S2.064
