高速铁路预制轨道板合理水养方法研究

轨道板脱模水中养护期间水化反应还在激烈进行,此时板的温度很高,且混凝土强度尚未形成,板在进行水养时若水温控制不当,则会导致轨道板产生初始缺陷。因此,本文以CRTSⅢ型普通钢筋混凝土轨道板为研究对象,开展现场试验,对轨道板水养过程温度及水养池水温进行实时动态监测,明确轨道板在水养过程中所承受的温度荷载,并建立有限元模型,分析轨道板在水养过程中在温度、水压力等荷载作用下的应力应变,探讨水养过程水温的合适范围,研究冬季施工水养方法。结果表明:(1)水养时轨道板会承受约5℃～7℃的整体降温荷载及100℃/m的温度梯度荷载;(2)在相同的水养条件下,整体温降相对于温度梯度对轨道板拉应力影响更大;(3)当作用在轨道板上的整体温降(温差)超过10℃时,轨道板最大拉应大于此时龄期混凝土的抗拉强度,需要提高水养水温;(4)冬季施工时宜采用逐步降低水温方法进行养护。

Study on Appropriate Water Curing Method for Precast Track Slab of High-speed Railway

During the curing of the track slab after demoulding in the water, the hydration reaction is still intense. At this time the temperature of the slab is very high and the strength of the concrete has not yet formed. If the water temperature is not controlled properly, the initial defect of the track slab will occur. Therefore, taking the CRTS Ⅲ ordinary reinforced concrete track slab as the research object, the field test is carried out to monitor dynamically the temperature of the track slab during water curing and the water temperature in the water curing pond in real time, clearly define the temperature load of track slab during the water curing, establish a finite element model for analyzing the stress and strain under the action of temperature, water pressure and other loads during the water curing, discuss the suitable range of water temperature during the water curing and study the water curing method in winter construction. The suitable range of water temperature in the process of water maintenance is discussed, and the water maintenance method in winter is studied. The results show that:(1) the track slab will bear the overall cooling load of about 5℃~7℃ and the temperature gradient load of 100℃/m;(2) under the same water curing condition, the overall temperature drop has a greater influence on the tensile stress of the track slab than temperature gradient;(3) when the overall temperature drop (temperature difference) is over 10℃, the maximum tensile strength of the track slab should be greater than that of the concrete at this age, therefore, the water curing temperature shall be improved;(4) the water temperature for curing of track slab should be gradually reduced in winter construction.