剛性鋪面堅硬層與反算動力修正係數之分析

The Analysis of Stiff Layer and Dynamic Correction Factor of Backcalculation for Rigid Pavement

周家蓓(Chia-Pei Chou) ； 陳靖翔(Ching-Hsiang Chen)

《中國土木水利工程學刊》 20卷4期 (2008/12) Pp. 573-583

https://doi.org/10.6652/JoCICHE.200812_20(4).0009

摘要

鋪面下方之堅硬層及動力效應，對落重撓度儀(falling weight deflectometer, FWD)試驗與反算結果有相當之影響，若充分掌握其特性，甚至可用於推算堅硬層或地下水位所在深度。本研究於台灣大學實驗道路之剛性鋪面進行FWD試驗，並利用有限元素法建構實驗道路剛性鋪面之軸對稱動力數值模型，以試誤法調整鋪面各層彈性模數與路基厚度等參數，使其模擬之感測器撓度歷時曲線回彈時間與FWD之撓度歷時相符，獲得各層之動力反算彈性模數，並同時判定淺層之地下水位與堅硬層所在深度。本研究亦利用此數值模型，探討剛性鋪面下方堅硬層對鋪面受FWD衝擊荷重產生之動力效應，並配合一般靜力反算程式，建立剛性鋪面反算之動力修正係數（面層約介於0.8~0.9，而路基則約為0.5），可有效改善一般靜力線性反算成效。

關鍵字

落重撓度儀 ； 鋪面反算 ； 堅硬層 ； 動力修正係數

並列摘要

Stiff layer beneath pavements and dynamic effects may affect falling weight deflectometer (FWD) tests obviously. It is possible to estimate the depth to stiff layer or water table, if the effects are recognized thoroughly. The FWD tests are conducted on rigid pavements of experimental pavement sections at National Taiwan University. The axisymmetric dynamic numerical models of the two rigid pavement sections are established through finite element method. If the simulated and measured deflection time histories are fitted by varying parameters such as the layer moduli and thickness of subgrade, the dynamic backcalculated layer moduli and the depth to stiff layer (or water table) could be determined simultaneously. The models are also adopted to analyze the dynamic effects of rigid pavements due to the stiff layer when subjected to FWD impulse loads. In addition, the dynamic correction factors are derived by statically backcalculating the deflections computed by dynamic finite element models to improve the traditional statically backcalculated results.

並列關鍵字

falling weight deflectometer FWD ； pavement moduli backcalculation ； stiff layer ； dynamic correction factor