Abstract
The lining of operating high-speed-railway tunnels suffers from cracks, the peeling of material, and other deteriorations and defects, all of which seriously affect driving safety. However, the trajectory of a falling block from the tunnel lining in a tunnel train wind environment and its impact on driving safety are unknown. To study the movement of falling blocks under a coupling effect of tunnel train wind and the local flow field of the falling blocks, a three-dimensional gas–solid-coupling numerical calculation model of spalling blocks–train–tunnel–air was established using FLUENT software The aerodynamic evolution mechanism governing the spalling blocks of the lining was analyzed, and we found that the falling process of a spalling block is affected by the coupling of its own characteristics and transient train wind. Train wind directly induced the horizontal motion of falling blocks, generated curves and eddy currents, and changed the motion state of spalled blocks. Furthermore, by comprehensively considering the motion trajectories of flaky and blocky blocks at different positions, the impact of spalling blocks on driving safety was obtained. The dangerous area of spalling blocks was approximately 5.5 m above the ground, which must be paid attention to. Our results provide guidance for the operation and maintenance of high-speed-railway tunnels.
Highlights
Two main forms of tunnel lining spalling blocks are encountered: cement mortar, flaky blocks located at the lining surface layer and blocky, concrete blocks located at the construction joint or joint of the tunnel lining [4]
Gas–solid-coupling calculation model of spalling blocks, a train, In three-dimensional this work, a three-dimensional gas–solid-coupling calculation model of spalling a tunnel, and air was established on theon basis theoffinite element calculation software, blocks–train–tunnel–air was established the of basis the basic theory of gas–solid interFLUENT
A three-dimensional gas–solid-coupling calculation model of spalling blocks, a train, The modified out-of-body vortex turbulence model (DDES) that is based on the two a tunnel, and air was established on the basis of the finite element calculation software, equations of SST k–ω was selected to simulate an unsteady, incompressible transient
Summary
High-speed-railway tunnels are prone to various problems such as lining cracks and falling blocks [1–3] owing to many factors such as a complex geological environment and construction defects. On 12 January 2016, lining blocks comprising the construction joint of the vault associated with a tunnel in Pingshan in China spalled off (cement block size: length: 10 cm, width: 5.5 cm, and thickness: 1.8 cm). This resulted in a train speed limit of 120 km/h and affected the normal running of the train for more than 2 h [5]. Several studies have used the real vehicle test [15,16], the model test [17], numerical simulations [18], and other methods These works considered the distribution characteristics of the train surface, tunnel wall, train wind in the tunnel, and micropressure wave at the entrance of the tunnel.
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