To address the shortcomings of the current research
and simulation accuracy of superlong pipe sheds, the
structural stress characteristics and deformation patterns of "longitudinal
and transverse support" system consisting of superlong pipe sheds and temporary inverted arches are investigated. This
system is specifically employed in highspeed railway
tunnels that cross operational railways in cohesive loess strata. First, a detailed
modeling of the superlong pipe shed is conducted using
solid elements to analyze the deformation of the strata and stress distribution
in the pipe shed. Next, realtime monitoring of the
longitudinal stress in the pipe shed is performed using grating optical fiber
test technology to reveal the influence range of tunnel excavation on the
longitudinal stress of the superlong pipe shed.
Finally, the mechanism of the "longitudinal and transverse support"
system is analyzed. The results are summarized as follows: (1) A wellintegrated superlong pipe shed transfers
vertical stress over a large longitudinal range to reduce stress on the steel
frame near the tunnel face. (2) The temporary arch forms a closedloop structure with the supporting structure after excavation, which
enhances the overall loadbearing capacity of the steel
frame and effectively controls the deformation of the loess tunnel. (3) The
minimum distance between the pipe sheds in the longitudinal and transverse
support system formed by pipe sheds and supporting structures should be greater
than twice the closing distance between the tunnel face and the supporting
structure. (4) The influence range of tunnel excavation on the longitudinal
stress of the superlong pipe shed is between 30 m in
front of the tunnel face and 20 m behind it. The strongly affected range is
from 10 m in front of the tunnel face to 5 m behind it. Moreover, the longer
the length of the pipe shed, the better its loadbearing
effect.
FENG Jimeng
,
TAN Yumei
,
YAO Shiyu
,
YAN Zhijian
,
ZHANG Junru
,
WANG Shengtao
. Deformation Control Mechanism of ShallowBuried
Cohesive Loess Tunnel and Related Countermeasures[J]. Tunnel Construction, 2023
, 43(10)
: 1712
-1722
.
DOI: 10.3973/j.issn.2096-4498.2023.10.007
