The invention provides a high-speed-railway 
karst roadbed structure with a pre-warning function and a repairing method thereof so as to effectively solve the technical difficult problems that as for atraditional high-speed-railway single 
karst roadbed, the collapse risk is high, the reinforcing effect is poor, 
karst caves cannot be accurately positioned, the 
engineering cost is high, and secondary repairing is difficult. The roadbed structure comprises a high-strength 
geotextile insulation layer, a light concrete filled-up body and a foundation 
bed, the first high-strength 
geotextile insulation layer is laid on a foundation, and the light concrete filled-up body is arranged on the first high-strength 
geotextile insulation layer in a filled-up mode. The foundation 
bed is arranged on the light concrete filled-up body in a filled-up mode, a first multi-point settlement 
observation system and a second multi-point settlement 
observation system are arranged on the bottom face and the top face of the light concrete filled-up body correspondingly, and a roadbed collapse pre-
warning system is arranged nearby a roadbed basal slope and used for collecting and 
processing roadbed settlement data observed by the first multi-point settlement 
observation system and the second multi-point settlement observation 
system and conducting automatic pre-warning when deformation of a roadbed tends toexceed the limit. A reserved post grouting repairing 
system is arranged in the light concrete filled-up body.