Characterization of Asphalt Concrete Mixtures in Flexible Pavements

柔性鋪面之瀝青混凝土材料特性分析與應用

李永鍵(Yung-Chien Lee)

《鋪面工程》 1卷2期 (2002/04) Pp. 18-38

摘要

在落重撓度儀成為探測柔性鋪面結構強度之主要儀器之際，鋪面層E值之回算則成為決定鋪面維修策略的最主要之工作項目之一，而回算之E值準確性是亟需要被重視的。本文首先敘述了在實驗室中所測得之典型的瀝青混凝土之特性與特徵，再進一步探討瀝青混凝土性質之時間－溫度、頻率－溫度重疊原理之應用。結果顯示，在實驗室量測瀝青混凝土性質時之力的加載時間，應該與落重撓度儀試驗時所施加之力的加載時間相接近，才能使回算的E值具有實用性與代表性。本研究進一步使用黏彈性之材料模式及有限元素方法作鋪面結構分析與驗證，瀝青混凝土材料之黏彈特性參數首先由實驗室取得，並試驗一系列的不同載重的重覆荷重試驗，這些試驗數據與試驗條件則被導入ABAQUS有限元數程式作分析與模擬。結果顯示，應用黏彈性材料模式之計算結果可以準確的描述瀝青混凝土在受不同程度重覆荷重之行為模式。更進一步的驗證則使用取自於落重撓度儀對實地柔性鋪面試驗之時間與變位的記錄數據，在鋪面結構中之瀝青混凝土材料則應用了彈性及黏彈性二種材料模式以為比較，分析結果顯示，使用黏彈性理論模式可以更精確的描述出柔性鋪面在受落重撓度儀試驗荷重的行為，有利於提昇回算值之正確性

關鍵字

黏彈性 ； 柔性鋪面 ； 瀝青混凝土 ； 落重撓度儀 ； 回算 ； 有限元素分析

並列摘要

With FWD being one of the major devices in determining the structural capacity of flexible pavement, backcalculation of pavement layer moduli has become the key task for making rehabilitation strategy. Typical material properties measured in the laboratory describing the characteristics of asphalt concrete are presented in this paper. Applications of time-temperature superposition principle and the frequency-temperature superposition principle are discussed. It was suggested that the loading frequency for which the moduli obtained in the laboratory should close to the frequency under the field loading conditions in order to meaningfully evaluate the computed moduli from FWD data. Investigation was further carried out using the viscoelastic material model in pavement structural analysis by finite element method. Relaxation moduli of asphalt concrete mixtures were obtained from the laboratory and a series of cyclic controlled-load/deformation tests were performed. These cyclic loading tests were further modeled using the laboratory data and analyzed by the ABAQUS finite element program. Good agreements were found between the laboratory measured responses and the computed values. A flexible pavement structure with actual FWD history measurements was analyzed using both the elastic and the viscoelastic material models. The result shows that the viscoelastic model can describe the actual behavior of a flexible pavement more closely than those of the elastic model.

並列關鍵字

viscoelastic ； flexible pavement ； asphalt concrete ； FWD ； backcalculation ； finite element analysis