CRTSⅡ型板式无砟轨道结构层间早期离缝研究

Analysis of Early Gap between Layers of CRTSⅡ Slab Ballastless Track Structure

在不同气候条件下现场观测CA砂浆灌注施工时的轨道板温度,得到实测的轨道板温度梯度。建立轨道结构力学计算模型,计算轨道板在实测温度梯度作用下的温度翘曲变形及应力。研究表明:气温和太阳辐射是影响轨道板温度梯度的主要因素;板面温度对温度梯度起控制作用;CA砂浆水化热对温度梯度有一定影响;在1d中,轨道板正、负温度梯度的交替变化引起温度翘曲压、拉应力的交替变化,是产生轨道结构层间早期离缝的最主要原因。因此,在早期温度场控制中,可采用有效的隔热或保温措施控制轨道板板面温度,避免出现较大的轨道板温度梯度,导致产生较大的温度翘曲应力,并根据CA砂浆强度增长规律,尽量延长扣压装置和精调千斤顶的拆除时间,从而有效地减少轨道结构层间早期离缝。

Slab temperature gradient is obtained by observing the temperature field of slab under which CA mortar is grouting in different climate conditions. The warping deformation and stress of track structure under the action of measured temperature gradient is analyzed by building its mechanical calculation model. The results show that air temperature and solar radiation are the main influence factors on temperature gradient. Slab surface temperature plays the control effect on temperature gradient on which the hydration heat of CA mortar has some effects. The alternative variations of the warping compressive and tensile stress which can easily lead to the emergence of early gap between layers of track structure are caused by daily alternative variations of the positive and negative temperature gradient. There are two effective ways to reduce the early gap between the layers of track structure. Firstly, using effective heat insulation measures to control the slab surface temperature so that the early temperature field can be controlled to avoid large temperature warping stress which is due to large temperature gradient of slab. Secondly, prolonging as possible the demolish time for compaction device and fine adjustment jack according to strength increasing law of CA mortar.