通过对我国中部山区复杂地形地质条件下高速铁路桥隧过渡段无砟轨道钢轨和 道床板纵向温度分布的连续观测，得到桥隧过渡段钢轨和道床板的纵向温度分布规律，并 提出适用于春季的桥隧过渡段钢轨和道床板纵向温度梯度荷载模式． 结果表明:从隧道外 到隧道内，钢轨温度变化幅值不断减小，隧道内 75 m 处的钢轨温度峰值出现时刻比隧道 外 22m 处的滞后 4h;钢轨纵向温度随隧道径深增加变化最大的位置位于 0 ～8m 区间，隧 道深 75m 以后，钢轨的温度变化幅度明显变小，基本稳定在 0． 2 ℃;道床板纵向温度随隧 道径深增加变化最大的位置位于 0 ～8m 区间，隧道深 25m 以后，道床板的温度变化幅度 明显变小，基本稳定在 1． 7℃;一天中钢轨和道床板温度沿纵向变化幅度最大的时刻出现 在 14:00 ～16:00;纵向温度梯度模式可分为钢轨和道床板两类，钢轨和道床板纵向温度 梯度均可采用分段函数进行拟合．

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.