The research on
determining the stability of the circumferential excavation face of a tunnel in
the nonhomogeneous clay layers primarily focuses on circular cross-section
tunnels, and the action law of different cross-section
shapes has important significance. Therefore, the stability of the
circumferential excavation face of a tunnel in a clay layer is investigated as
a function of the factors influencing the stability, such as various cross-section shapes, buried depth ratios, soil weights, and heterogeneous
strength that increases linearly with depth. The upper limit finite element
method of rigid translational motion element is used to investigate the
relationship between the critical load ratio and potential failure mode. The
results show the following. (1) For the case of the same height of tunnel, the
critical load ratio under the failure limit state for the straight wall of the
horseshoeshaped tunnel is slightly lower than that of
the circular tunnel. However, the upper limit solution obtained for the elliptical
tunnel decreases with increasing span. The critical load ratio of tunnel
failure is positively related to the soil heterogeneous strength and negatively
correlated to the depth of soil. (2) The tunnel′s
buried depth is affected by the strength of soil heterogeneity and the soil
weight. Moreover, it is noted that failure range is determined by the shape of
cross-section and buried depth, and it is considerably
less sensitive to other factors from the failure mode of the sliding line
obtained using the upper limit finite element method. Therefore, the upper
limit solution with the critical load ratio agrees well with the centrifuge
test results. This demonstrates that the upper limit method of the moving
element and the fitting formula of the upper limit solution can be used to
evaluate the stability in the circumferential excavation face of tunnels in the
nonhomogeneous clay layer.
LIU Guoliang
,
HUANG Feiheng
,
LUO Jingjing
,
YANG Feng
.
Upper Limit Analysis of Translational Rigid Finite
Elements for Determining Circumferential
Excavation Stability of Tunnels in Nonhomogeneous Clays
[J]. Tunnel Construction, 2021
, 41(12)
: 2073
-2082
.
DOI: 10.3973/j.issn.2096-4498.2021.12.007
