Abstract:

According to the continuous observation of longitudinal temperature distribution of ballastless tracks and roadbed slabs in the high-speed railway bridge-tunnel transition section in China's central complex mountainous area,the corresponding temperature distribution laws were obtained,and a suitable spring longitudinal temperature gradi- ent load model was established.Analytical results show that (1) from the outside to the inside of the tunnel,the temperature variation amplitude of the rail gradually decreases,and the temperature peak time of 75 meters inside the tunnel lag for 4h than that of 22 meters outside the tunnel; (2) the longitudinal temperature of the rail increa- ses with the increase of the tunnel's diameter and the maximum position range locates at 0 ～8m; when the tunnel depth is more than 75m,the temperature variation amplitude of the rail obviously becomes small and remains stable at 0.2℃; (3) the longitudinal temperature of the roadbed slab increases with the increase of the tunnel's diameter and the maximum position range locates at 0 ～8m; when the tunnel depth is more than 25m,the temperature vari- ation amplitude of the slab obviously becomes small and remains stable at 1.7℃; (4) the maximum longitudinal temperature variation amplitudes of both the rail and the slab in a day appear in the duration of 14:00 ～ 16:00; and (5) the longitudinal temperature gradient mode can be divided into two types: one is the rail type and the other the slab type,and the longitudinal temperature gradients of both the rail and the slab can be fitted by the piecewise function.

Key words: bridge-tunnel transition section, track structure, temperature field, central mountainous area, ex- perimental investigation