A multilayer mechanical
model comprising a surface-mounted
optical fiber sensing element with a core layer, protective layer, substrate
layer, and measured layer is constructed using optical fiber sensing
technology. The strain transfer mechanism of the optical fiber is analyzed, and
a strain transfer rate formula for a surface-mounted
optical fiber sensing element is derived. The accuracy of the sensing element
in detecting the structural shape of tunnel segments is verified. A 1∶20 scale model is employed to perform experimental investigations by
measuring the strain variations in the segments under different water and earth
pressures. Numerical simulations using ANSYS are conducted to compare the
strain responses of the tunnel segment structure under two load scenarios: with
and without water pressure. The results also reveal the influence mechanism of
water-soil coupling pressure on tunnel segment
deformation. The findings are summarized as follows: (1) The average strain
transfer rate of the optical fiber sensing element reaches 95.1 % at a grating
length of 10 mm. (2) Uniform water pressure stabilizes the deformation of the
tunnel segment structure to a certain extent. (3) Under water-soil coupling pressure, the tensile and compressive strain changes
are unsynchronized. The compressive strain change at the arch waist precedes
the tensile strain change at the crown, indicating a higher sensitivity of the
arch waist to water-soil coupling pressure. (4) In a
water-pressure stratum environment, the displacement of
the tunnel segment structure exhibits a fluctuating trend as the stratum load
increases from 0 to 1.6 MPa.
(5) When the load further increases from 1.6 to 2.4 MPa, the displacement of
the tunnel segment structure follows a linear trend.
SONG Ming
,
LIU Jiguo
,
SHU Heng
,
PENG Wenbo
,
XING Rongjun
,
LI Zheng
. Experimental and Numerical
Simulation of Structural Shape Perception of Tunnel Segments Based on Optical Fiber Sensing[J]. Tunnel Construction, 2024
, 44(10)
: 1993
-2004
.
DOI: 10.3973/j.issn.2096-4498.2024.10.008
