双块式无砟轨道温度荷载取值方法的试验研究

摘要

为研究双块式无砟轨道的温度荷载取值方法,对达坂城地区一段10 m 长双块式无砟轨道进行连续8个月的无砟轨道温度测试。测试结果表明：无砟轨道温度与近地表气温呈现出以日和年为周期的变化特征；道床板年温度极值可通过气温极值根据道床板厚度扣除相应的统计温差值得到；道床板和支承层日温差与日气温差基本成正比,可通过日气温差得到无砟轨道日温差荷载。不同深度处的无砟轨道温度存在着梯度和滞后现象,道床板温度约滞后于气温2 h,支承层温度约滞后10 h。道床板温度梯度分布较宽且不均匀,98.34%的时段在-30~60℃/m；支承层温度梯度分布较窄,99.73%出现在-10~20℃/m。每天的温度梯度幅值近似与日气温差成正比,夏季的温度梯度幅值高于冬季。%In order to study the value determination method of temperature load on ballastless track,an eight-month temperature field test was carried out on a 10 m long bi-block ballastless track in Dabancheng.The test results showed that the ballastless track temperature and the near-surface air temperature varied periodically with the daily and annual cycles.The annual temperature extremes of ballastless track can be obtained through the air temperature extremes after the corresponding statistical temperature difference was deducted based on track slab depth.The diurnal temperature range of track slab and base plate is approximately linear to that of the surface air temperature.The diurnal temperature load on slab track can be derived from the diurnal air tem-perature range and the corresponding scale factor.There were gradients and lags between temperatures in slab tracks at different depths.The temperature in track slab was 2 hours behind the surface air temperature while the temperature of the base plate was about 10 hours behind every day.The temperature gradient distribution in track slab was relatively wide but extremely uneven,with 98.34% of the temperature gradient falling in -30~60 ℃/m range for track slab.The temperature gradient distribution in base plate was relatively narrow with 99.73% falling in the -10~20 ℃/m range.The temperature gradient amplitude was approximately pro-portional to the daily surface air temperature variation.The temperature gradient amplitude in summer was lar-ger than in winter.