水泥混凝土路面板硬化翘曲时程变化实测分析

Experimental Investigation of Built-in Curling Evolution in Full Scale Concrete Pavement

通过铺筑足尺水泥混凝土路面,在连续观测混凝土板不同深度早龄期温度场的同时,基于自主开发的竖向变形观测装置观测了端部自由板和内部约束板在整个早龄期的竖向翘曲变形历史。在此基础上推导了基于五测点的等效线性温度梯度计算公式,提出了基于板的翘曲变形时程和温、湿度时程的水泥混凝土路面板硬化翘曲直接量测方法,为硬化翘曲存在形态的试验量测提供了一种新的分析方法。分析表明:端部自由板翘曲变形幅值(-0.3~1 mm)远高于内侧完全约束板的相应位置(-0.2~0.3 mm)。受约束程度、湿度梯度、温度梯度等因素的影响,板的翘曲呈现显著的非对称性。约束稳定区域等效线性温度梯度随龄期逐渐衰减和稳定至1℃/m,自由板边与自由板角等效内嵌温度梯度时变规律多样。水泥混凝土路面板等效内嵌温度梯度主要集中在-25~25℃/m范围内,约占水泥混凝土路面设计所采用温度梯度的25%,不可忽略,但具体幅值需依据具体路面结构、板块尺寸、早龄期温湿度历史以及混凝土材料性能等因素通过计算或现场实测进行评估。

Based on the constructed full scale cement concrete pavement,during continuous observation of the early age temperature field of concrete slab in different depths,the histories of vertical curling in the ending slabs and internal slabs during the whole early-age are measured by the self-developed vertical deformation measuring device. In addition,the calculation formula of equivalent linear temperature gradient（ EBITG） based on five-position temperature data is derived. A kind of approach of directly measuring the built-in curling in cement concrete pavement slab based on the curling,temperature and moisture histories of the slabs is proposed,which provided an innovative approach for measurement the built-in curling in the slab by test. The analysis result show that（ 1） the values of the curling at the slabs in the end（-0. 3-1 mm）are far higher than that in the internal completely restrained slab（-0. 2-0. 3 mm）;（ 2） the curling shapes of the slabs display obvious asymmetry due to the effects of restraint degree,moisture gradient and thermal gradient;（ 3） the EBITG in the slab with fixed restraint reduces and stabilizes at the level of 1 ℃/m with the age,the EBITGs in the edges and angles of ending slabs always demonstrate diversity but focus in the range of-25-25 ℃/m,it makes up a relatively 25% of the design value adopting in the cement concretepavement design,which is not negligible,while the specific values should be evaluated according to the details of pavement structure,slab geometry,temperature and moisture history during early-age and material property of concrete.