| In Japan, it is common for road tunnels to be constructed
using conventional tunnelling method. According to
technical standard of road tunnel and its explanation (for
structure) (2008) and Standard Specification for Tunnelling
(2016), in sections with an inner width of approximately 10
meters and where no external forces other than self-weight
are expected, cast-in-place unreinforced concrete with a
design thickness of 30 cm is commonly applied. These
specifications are not determined through performance
assessments but have become assumed standards for
standard sections based on past construction records and the
cost-effectiveness and consistent quality of unreinforced
concrete. In tunnels where construction satisfying the above
specifications has been conducted in standard sections,
instances of significant deterioration in structural stability
during the operational period are extremely rare. Therefore,
despite not being determined through performance
assessments, it can be considered that the specifications for
conventional lining work ensure load-bearing capacity and
other performance criteria.
In recent years, in Japan, there have been cases where the
adoption of precast lining work has been considered for the
purpose of improving the speed of construction, among
other reasons. However, the adoption of precast lining work
in mountain tunnels in Japan is very rare, and there are still
aspects where the impact of joint structures, joint positions,
and the number of joints between precast sections on the
failure mechanism and structural strength of the lining has
not been elucidated.
In this research, we conducted large-scale loading tests usingtwo types of precast lining work with different joint
structures, aiming to understand the mechanical properties
of precast lining work, including load-bearing capacity and
failure mechanisms, in comparison to conventional lining
work. |
