Influence of the initial state of the track structure on the track–interlayer interface under high-temperature load

CRTS Ⅲ slab ballastless track is a high-speed railway track structure with completely independent intellectual property rights in China. The use of this type of track structure reduces the risk of high-temperature seam disease at the weak position of the track–interlayer interface to a certain extent. Because of the objective difference between the initial state and the design theory state of the ballastless track structure after construction, the influence of the initial state difference change on the service performance of the interface between the layers of the track structure during the operating period needs to be investigated.

Based on the concrete rebound test, the mechanical state of each layer of the CRTS Ⅲ slab ballastless track was tested. Based on the measured values of the concrete strength of each component of the track structure, the initial difference deviation of the track structure is quantified. Based on the initial difference quantitative data of the track structure and the high-temperature monitoring data of the track slab surface, combined with the ANSYS general finite element software, the spatial simulation analysis model test of the CRTS Ⅲ slab ballastless track was designed. Moreover, the influence of the initial state difference change on the service performance of the track–interlayer interface of the track structure during the operating period was analyzed.

The sampling test results of the initial mechanical state of each layer of the track structure after construction showed that, on the new unoperated line, the measured values of the concrete strength of the track slab and the self-compacting concrete layer have an initial difference deviation of −1.30%–7.42% and −9.98%–2.79%, respectively, compared with the design values. Combined with the initial difference quantitative data, the spatial simulation analysis test model of the CRTS Ⅲ slab ballastless track is established. The analysis results showed a deviation from the original design intention, which will not be conducive to the bonding of the interface. Especially when the strength of the self-compacting concrete is high, the transfer of interlayer temperature force is limited, and the interface damage area increases by 95.65% under adverse load.

The deviation between the initial state of the track structure after construction and the original intention of the design cannot be avoided, which leads to the unfavorable bonding of the interface. The high strength of the self-compacting concrete should be avoided during construction, and different from other ballastless track structures, gap disease at the edge of the slab can be easily induced. For the maintenance and repair work of the CRTS Ⅲ slab ballastless track during the operating period, the idea should be adjusted to supplement and check the service status of the track–interlayer interface corresponding to the limit block.