Based on analyzing the mechanical environment of tunnels with different causes of upper arch deformation,a deformation transmission model of the tunnel bottom heave of ballasted and ballastless tracks under tunnel bottom loads is constructed to obtain the transmission law from this deformation to the rail surface,and a functional relationship between tunnel bottom load and deformation transmission ratio is established.The results show that when the upper arch deformation is transmitted at the bottom surface of the primary lining-the surface of the infill layer,the amplitude decreases and the wavelength increases;when the deformation is transmitted at the ballast bed surface-rail surface,both amplitude and wavelength decrease;when it is transmitted in the ballast bed,the wavelength and amplitude of the ballasted bed decrease,while the wavelength of the ballastless bed increases and the amplitude of it is basically unchanged.Changes of tunnel bottom load magnitude and longitudinal distribution length shift the amplitude transmission curve as a whole,in which the load magnitude mainly changes the change rate of the wavelength,while the load longitudinal length mainly changes the initial wavelength.It is easier to control the rail surface amplitude and wavelength under the tunnel bottom loads of less than 250 kPa and more than 27.8 m in length when the ballasted track is selected.When the load exceeds 250 kPa or the length is less than 27.8 m,it is easier to control the rail surface amplitude and wavelength by choosing the ballastless track.
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