ABSTRACT

Pavement temperature is one of the most important factors influencing the performance of flexible pavements. The major components of the Earth's heat balance system are downwelling shortwave radiation (D-SWR) from the sun, downwelling longwave radiation (D-LWR) from the atmosphere, and upwelling longwave radiation (U-LWR) emitted by the warm pavement surface. The Pavement ME Design (PMED) software (AASHTO, 2015 AASHTO, 2015. Mechanistic-empirical pavement design guide–a manual of practice. Washington, DC: AASHTO. [Google Scholar]. Mechanistic-empirical pavement design guide–a manual of practice. Washington, DC: AASHTO) computes temperature distributions in the pavement over depth and time using algorithms originally proposed by Dempsey et al. (1985 Dempsey, B.J., Herlache, W.A., and Patel, A.J., 1985. Environmental effects on pavements: theory manual. FHWA/RD-84-115, Federal Highway Administration, US Department of Transportation, vol. 3. [Google Scholar]. Environmental effects on pavements: theory manual. US Department of Transportation, Federal Highway Administration). These algorithms are largely empirical, depend heavily on imprecise corrections for cloud cover, and in some parts contradict atmospheric physics. Improved models for the major radiation components proposed here include: (1) D-SWR values modelled by the MERRA-2 climate re-analysis product from NASA (Rienecker et al., 2011. MERRA: NASA’s modern-era retrospective analysis for research and applications. Journal of Climate, 24, 3624–3648); (2) D-LWR modelled using the Idso (1981 Idso, S.B., 1981. A set of equations for full spectrum and 8-to 14-μm and 10.5-to 12.5-μm thermal radiation from cloudless skies. Water Resources Research, 17, 295–304.[Crossref], [Web of Science ®] , [Google Scholar]. A set of equations for full spectrum and 8-to 14-μm and 10.5-to 12.5-μm thermal radiation from cloudless skies. Water Resources Research, 17, 295–304) empirical parameterisation with a physics-consistent adjustment for cloud cover; and (3) U-LWR calculations without the physics-inconsistent cloud cover adjustment embedded in PMED. The D-SWR and D-LWR radiation models were evaluated via comparisons against ground-based radiation observations at 21 locations in the Solar Infrared Radiations Stations (SIRS) database. The MERRA-2 estimates of D-SWR, although not perfect, were found to agree substantially better than the current PMED models with the ground truth SIRS. The D-LWR fluxes from the Idso (1981 Idso, S.B., 1981. A set of equations for full spectrum and 8-to 14-μm and 10.5-to 12.5-μm thermal radiation from cloudless skies. Water Resources Research, 17, 295–304.[Crossref], [Web of Science ®] , [Google Scholar]. A set of equations for full spectrum and 8-to 14-μm and 10.5-to 12.5-μm thermal radiation from cloudless skies. Water Resources Research, 17, 295–304) parameterisation were also found to agree substantially better than the current PMED with the ground truth SIRS, with particularly striking improvements for the all-sky (i.e. including clouds) condition. A limited series of flexible pavement performance analyses were conducted to illustrate the potential practical impact of these radiation model changes. The new radiation models produced significantly higher pavement temperatures that lead to substantially higher total rutting, asphalt rutting, and bottom up fatigue cracking. These changes in distress magnitudes must be evaluated in qualitative terms only, as all analyses used the same field calibration coefficients for the distress models. The primary conclusion from this work is that the current radiation models incorporated in PMED are inaccurate and, in some cases, inconsistent with fundamental atmospheric physics. This can have significant impacts on predicted pavement performance. It is recommended that the current PMED radiation models be replaced by the new D-SWR, D-LWR, and U-LWR. New field calibration of the empirical distress models would be required after incorporating the new radiation models.

摘要

路面温度是影响柔性路面性能的最重要因素之一。地球热平衡系统的主要组成部分是来自太阳的下行短波辐射（D-SWR）、来自大气的下行长波辐射（D-LWR）和温暖路面发射的上行长波辐射（U-LWR）。路面 ME 设计 (PMED) 软件 (AASHTO, 2015AASHTO，2015 年。机械经验路面设计指南——实践手册。华盛顿特区：AASHTO。 [谷歌学术]。机械经验路面设计指南——实践手册。华盛顿特区：AASHTO）使用最初由 Dempsey 等人提出的算法计算路面深度和时间的温度分布。(1985 年 Dempsey，BJ，Herlache，WA和Patel，AJ，1985 年。对路面的环境影响：理论手册。FHWA/RD-84-115，美国交通部联邦公路管理局，第一卷。3 . [谷歌学术]。对路面的环境影响：理论手册。美国交通部、联邦公路管理局）。这些算法在很大程度上是经验性的，严重依赖于对云量的不精确校正，并且在某些部分与大气物理学相矛盾。这里提出的主要辐射成分的改进模型包括：（1）由 NASA 的 MERRA-2 气候再分析产品建模的 D-SWR 值（Rienecker 等人，2011 年。MERRA：NASA 对研究和应用.气候杂志, 24, 3624–3648); (2) 使用 Idso (1981 伊索，SB，1981 年。一组来自无云天空的全光谱和 8 至 14 微米和 10.5 至 12.5 微米热辐射的方程。水资源研究，17, 295 – 304。[交叉引用]、[Web of Science®]、 [谷歌学术]。无云天空的全光谱和 8 至 14 微米和 10.5 至 12.5 微米热辐射的一组方程。水资源研究, 17, 295–304) 经验参数化，对云量进行物理一致的调整；(3) U-LWR 计算没有嵌入 PMED 中的物理不一致云量调整。D-SWR 和 D-LWR 辐射模型是通过与太阳红外辐射站 (SIRS) 数据库中 21 个地点的地面辐射观测结果进行比较来评估的。MERRA-2 对 D-SWR 的估计虽然不完美，但被发现比当前 PMED 模型与地面实况 SIRS 的一致性要好得多。来自 Idso 的 D-LWR 通量（1981 伊索，SB，1981 年。一组来自无云天空的全光谱和 8 至 14 微米和 10.5 至 12.5 微米热辐射的方程。水资源研究，17, 295 – 304。[交叉引用]、[Web of Science®]、 [谷歌学术]。无云天空的全光谱和 8 至 14 微米和 10.5 至 12.5 微米热辐射的一组方程。水资源研究, 17, 295–304) 参数化也被发现比当前的 PMED 与地面实况 SIRS 的一致性要好得多，特别是对全天空（即包括云）条件有显着的改进。进行了一系列有限的柔性路面性能分析，以说明这些辐射模型变化的潜在实际影响。新的辐射模型产生了显着更高的路面温度，从而导致明显更高的总车辙、沥青车辙和自下而上的疲劳开裂。遇险幅度的这些变化必须仅在定性方面进行评估，因为所有分析都对遇险模型使用相同的现场校准系数。这项工作的主要结论是，当前纳入 PMED 的辐射模型是不准确的，并且在某些情况下，与基本大气物理学不符。这会对预测的路面性能产生重大影响。建议将当前的 PMED 辐射模型替换为新的 D-SWR、D-LWR 和 U-LWR。在合并新的辐射模型后，将需要对经验遇险模型进行新的现场校准。