To determine the stress release rate of shield
tunneling face in uppersoft and lowerhard strata, the variation rules of the stress release rate of
surrounding rock under various proportions of hard and soft rocks on the tunnel
face and buried depths are studied via numerical simulations using an existing
stress release rate calculation method by volume loss rate iteration. The
results are compared with the field data collected for Guangzhou metro line 21.
The results indicate the following: (1) For shield tunneling in the interface
between hard and soft rocks, the initial stress release rate of surrounding
rock ranges from 24% to 36%, and it linearly increases with the proportion of hard rocks on tunnel face.
(2) Compared with the strata condition, the influence of the buried depth on
the stress release rate is less. In addition, in the simulation of shield
tunnel passing through uppersoft and lowerhard strata, dynamically adjusting the stress release rate under
different excavation steps according to the changes in surrounding rocks is
feasible.
WANG Shimin
,
PENG Xiaoyu
,
CHEN Bing
,
WANG Xianming
,
RUAN Lei
. Surrounding Rock Stress Release Rate of Shield Tunnel
in UpperSoft and LowerHard Strata[J]. Tunnel Construction, 2022
, 42(4)
: 594
-601
.
DOI: 10.3973/j.issn.2096-4498.2022.04.007
