Abstract: The deformation control standards for tunnel crossing underneath highspeed railway is of great significance. As a result, the interaction among highspeed railway tracks, fasteners and subgrade is studied by field investigation and statistical analysis, and the formulation method of subgrade settlement control standards for highspeed railway is proposed. The study results show that: (1) The maximum allowable deformation of the track is determined by the maximum adjustable amount of the track fastener, the current adjustment amount and the current smoothness, etc. (2) An appropriate safety factor for the control standards of track deformation should be selected according to the surrounding environment and the actual running speed of the train, reducing on the basis of the maximum allowable deformation. (3) The deformation control standard of subgrade shall be determined according to the correlation between subgrade and track deformation. The deformation control standards for the track is applicable to the ballastless track of highspeed railway, and the deformation control standard of the subgrade is applicable to the subgrade deformation caused by shield tunneling in soil stratum.

Key words: highspeed railway subgrade, undercrossing tunnel, settlement control standards, track deformation, subgrade deformation