水泥混凝土路面早龄期应力行为试验研究

EXPERIMENTAL STUDY ON THE EARLY-AGE STRESS BEHAVIOR OF CEMENT CONCRETE PAVEMENT

  • 摘要: 为了解路面板早龄期应力性状与行为特征,基于福建夏季高温、冬季低温、隧道恒温进行了3种典型环境条件的路面板早龄期行为现场试验。采用无应力圆筒装置去除路面板温湿度无应力应变,基于应变历史结合步进法考虑徐变松弛获得路面板典型监测位置应力性状和时程。同步监测路面板早龄期温度场和整板翘曲,比较路面板早龄期应力与温度梯度、翘曲变形的相互关系。研究显示,路面板早龄期应力一般存在压应力、拉应力、应力波动循环3个阶段,应力波动循环初期存在一个松弛阶段。路面早龄期应力主动影响因素有水化放热、环境场温湿度变化、翘曲变形和重力的联合作用,初期水化热升降温效应显著,后期温度翘曲效应显著。被动影响因素有水泥混凝土早龄期行为、结构约束、边界条件等。夏季施工面板早龄期应力和翘曲量级显著高于冬季,隧道恒温条件下面板由于湿度收缩会形成板角始终向上的凹形固化翘曲。早龄期应力波动和松弛过程的存在,造成路面板初期运营的一段时间的应力与后期正常服役期并不相同,需要规避可能与设计状态不符的初期不利工况。

     

    Abstract: To understand the behavior and characteristics of the early-age stress of cement concrete pavement, field monitoring tests were carried out at the early age of slabs constructed under typical environmental conditions in Fujian such as high temperature in summer, low temperature in winter and constant temperature in tunnel. Non-stress strain of temperature and humidity was removed by a nonstress cylinder device. Based on the strain histories and considering the creep relaxation, the stress state and histories at typical positions of the slabs were obtained by a step-by-step numerical method. The early-age temperature field and curling deformation were monitored. The relationship between early-age stress, temperature and curling was compared. The results show that the early-age stress of pavement has three stages, namely, compressive stress, tensile stress and stress fluctuating cycle. Stress relaxation stage exists in the initial stage of stress fluctuating cycle. Active factors effecting the early-age stress include hydration heat release, environmental temperature, curling deformation and gravity, and their combined action. The effect of hydration heat is significant in the preliminary stage, while the effect of temperature curling is significant in the later stages. Passive factors effecting the early-age stress include the early-age concrete behavior, structural constraints and boundary conditions. The early-age stress and the curling of pavement constructed in summer are higher than that constructed in winter. Under the condition of stable temperature in tunnel, there is a concave built-in curling in the slab with the corners being always upward due to humidity shrinkage. The existence of stress fluctuation and relaxation process in the early age causes the stress in the initial service period to be different from the stress in later service period. It is necessary to avoid the initial adverse conditions that may be inconsistent with the design state.

     

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