INFULENCE MECHANISM OF HIGH-FREQUENCY VIBRATION ON CONCRETE ANTIFREEZE AND APPLICATION IN CONSTRUCTION OF TUNNELS IN COLD REGIONS

To explore new technology and new methods in tunnel secondary lining construction in cold region， according to the second double of the Lanzhou-Xinjiang Ｒailway，it was carried out experimental study of the structural reliability and the performance stability of frequency vibration system for tunnel secondary lining construction，the construction technology was determined and the matters needing atteation as well as the insulation measures were also summarized． By field trials study，it was found that 20 ～ 40 s of continuous vibration of C35 concrete whose slump was 16. 8 cm and water-binder ratio was 0. 37，could achieve the desired surface quality and strength of the concrete． Meanwhile frost resistance test showed that the concrete mass loss rates were maintained at 3% or less，the relative dynamic elastic modulus in the range of 80% to 90%，after 300 cycles of freeze-thaw，thus reaching the frost resistance grade of F300． The vibration test and the detection results showed that the high frequency vibrator technology could be used for tunnel secondary lining construction in cold region．