To solve the problem of safety bearing load for the
curved middle wall during construction of the doublearch
tunnel, the mechanical evolution law and bias mechanism of the curved middle
wall during the construction of a composite doublearch
tunnel in Zhejiang province, China, are analyzed using numerical calculation
and field monitoring methods. Furthermore, the influence laws of the curved
middle wall thickness and the main tunnel excavation distance on the stress and
bias effect of the curved middle wall are investigated from the design and
construction perspectives. The results reveal the following: (1) Excavation of
the top heading of the main tunnel has a significant influence on the stress
distribution of the curved middle wall. The stress increase accounts for
roughly half of the total stress value. The curved middle wall bears the
majority of the vertical stress, and the smallest crosssection is the least favorable position. (2) Unsymmetrical
excavation of the multiarch tunnel causes the bias
load on the curved middle wall, leading to deflection to the side of the first
tunnel. The transition from the first tunnel excavation to the later tunnel
excavation has a significant deflection effect. (3) Thickness of the curved
middle wall has a significant influence on its stress distribution and
deflection effect. The reduction in thickness of the middle wall reduces the
structure′s bearing capacity. When the thickness is 1.3
m, the stress in the curved middle wall increases dramatically, potentially
resulting in collapse instability. (4) The main tunnel excavation distance has
a greater influence on the stress distribution of the curved middle wall, but
has no effect on the final stress of the curved middle wall. The deflection
moment of the curved middle wall increases as the excavation distance of the
main tunnel increases, and the deflection effect lasts longer.
XU Qing
,
ZHANG Sulei
,
LIU Chang
,
ZHANG Guodong
,
CHEN Degang
.
Spatial and Temporal Evolution Characteristics of
Mechanical Behavior of Curved
Middle Wall of Composite DoubleArch Tunnel
[J]. Tunnel Construction, 2022
, 42(6)
: 1022
-1032
.
DOI: 10.3973/j.issn.2096-4498.2022.06.010
