In order to improve the efficiency of EPB shield
tunneling, nonfull chamber tunneling mode is often used in tunnel construction.
While the nonfull chamber tunneling mode in waterrich strata often encounters problems such as large overexcavation due to instability of excavation face. Aiming at the
seepage stability of excavation face during nonfull
chamber tunneling, the study is carried out combined with an instability
phenomenon of excavation surface at a bid section of Jinan metro line R2.
First, the selfmade excavation surface seepage failure
test apparatus are used to study the seepage failure conditions and types under
seepage condition and nonfull chamber tunneling.
Second, the sand production rules for different seepage failure types are
analysed. Last, six types of strata with different gradation are set according
to the content of movable fine particles in soil, and the relationship between
soil gradations and critical hydraulic gradient is investigated. The results
show that: （1）Seepage failure
occurs in the formation under the action of seepage, and the critical hydraulic
gradients of seepage failure for nondevelopment type
and development type are 0.5 and 0.8 respectively. （2）The sand quality of nondevelopment seepage
failure increases first and then becomes stable gradually, while the sand
quality of development seepage failure continues to increase, which is
characterized by gradual failure. （3）The relation between movable filling content Pf and its critical hydraulic gradient is
established.
HU Jiannan, ZHU Wei QIAN Yongjin, XING Huitang, WANG Lu, LU Kaijun, WEI Bin
.
Study on Seepage Failure of Excavation Face of EPB
Shield Tunneling with
NonFull Chamber
[J]. Tunnel Construction, 2021
, 41(S1)
: 240
.
DOI: 10.3973/j.issn.2096-4498.2021.S1.030
