The pipe curtain method applied in shallowburied
underground structures has many disadvantages, such as failure coordination of
pipe curtain segments and lowsupport efficiency.
Therefore, a novel structure called the underground bundled integrated tunnel
(UBIT) based on transverse prestress is proposed. This
structure uses rectangular pipes as the supporting structures; the pipes are
connected using a lock catch and concrete by applying tensioning transverse
prestress, thus forming an integrated stress body. To further investigate the
influence of the arrangement of unbonded tendons on the mechanical properties
of the UBIT, bending and shear tests were conducted,
and the quadratic and doublelinear arrangements of the unbonded tendons are
comparatively analyzed. The following results were obtained. (1) The crack load
and failure mechanism of the bond interface are not affected by the linear
arrangement of the unbonded tendons. (2) The ultimate bending moment bearing
capacity of the joints under the quadratic arrangement is 1.4~1.6 times that of
the double linear arrangement when the joints are opened and under the same
prestress. (3) In the shear test, when there is no opening or dislocation of
the joint, the application of prestress can be regarded as an external
horizontal force. The shear stiffness of the joint increases with the
horizontal force, and the quadratic arrangement is 7%~9% more in shear
stiffness than that of the joint in the doublelinear arrangement under the same
horizontal force. (4) The actual stress of the structure possesses a composite
state of bending and shearing, and joint cracking causes a significant decline
in the shear capacity of the structure.
BI Xiangli
,
WANG Xiuzhi
,
ZHANG Zhongjie
,
PAN Weiqiang
,
JIAO Bochang
,
LIU Xian
. Analysis of Influence of Bundled Integrate Structure
of an Unbonded Prestressed TendonLine
in Saturated SoftSoil Area[J]. Tunnel Construction, 2023
, 43(8)
: 1299
-1307
.
DOI: 10.3973/j.issn.2096-4498.2023.08.004
