Research on damage characteristics and contact interface evolution behavior of double-block ballastless track considering tunnel floor heave

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Excessive railway tunnel floor heave (TFH) will reduce the durability of the track structure and jeopardize train operation safety. The TFH characteristics were fitted into cosine and bilinear curves according to the monitoring data. A nonlinear failure analysis model of double-block ballastless track under TFH was established. The deformation transfer law, structural damage mechanism and the interlayer bonding interface failure evolution of the track structure under different TFH characteristics were explored. The results show that the deformation of TFH can be well mapped to the track. The amplitude transfer ratio is less than 100 %. The maximum wavelength transfer ratio under the cosine and bilinear TFH is 129.3 % and 127.5 %, respectively. To avoid the damage of track structure, when the wavelength is 10 m, the amplitude of cosine and bilinear TFH should be controlled at 2.5 mm and 0.5 mm respectively. When the wavelength is greater than 10 m, the amplitude can be appropriately increased. To avoid interlayer bonding cracking, the cosine and bilinear amplitudes with a wavelength of 10 m should be controlled at 5 mm and 1.5 mm, respectively. The track-tunnel interlayer debonding failure under the cosine curve occurs at the edge of the TFH, while the bilinear curve occurs at the center and edge of the TFH. The gaps under the cosine and bilinear TFH exhibit double-peak and multi-peak shapes, respectively. This study can provide theoretical guidance for controlling the performance degradation of track structure caused by TFH.