舖面落重式撓度儀之校正與成效評估研究

A Study on the Significance of Calibration and Performance from Pavement Falling Weight Deflectometer

周明輝(Min-Hui Chou)

指導教授 ： 張達德

中原大學/工學院/土木工程研究所/碩士(2001年)

https://doi.org/10.6840/cycu200100100

摘要

由於歐美各國在路面工程上的主導性研究，皆以路面各層材料的回彈模數做為路面結構強度及績效評估之指標，而落重撓度儀(Falling Weight Deflectometer,簡稱FWD)可以直接量測路面撓度值再加以回算鋪面結構各層材料的回彈模數，具有維持鋪面完整及量測迅速之特性，目前已逐漸取代傳統直接鑽孔取樣的實驗方式，而被廣泛地應用來評估現有路面的結構強度，對於路面工程的完工驗收、維護策略修定及加鋪設計有極大之幫助。
國內由國道高速公路局首先引進一部落重撓度儀（型號為Dynatest 8000），自民國84年至今，並未對儀器之個別感應子以及系統整體進行相關的校正評估研究，因此對儀器目前所量測數據之可靠性並無法加以確認。故本研究將針對儀器本身之各感應子進行相關的校正與檢測工作；並將動態回算程式DBFWD與傳統靜態回算程式WESDEF之回算結果與現地各層鑽心或重模試體之回彈模數MR進行比對，以作為落重式撓度儀之功能性校正，並使儀器對路面成效評估分析之可靠性可以獲得確保。
研究結果顯示，在依據ASTM D4694-96規範與原廠校正程序進行校正，以及速度規之絕對校正後可知，儀器各感應器仍維持穩定與準確；而DBFWD與WESDEF兩套回算程式則以DBFWD所回算之結果較為準確且合理，且DBFWD對於瀝青混凝土(AC)面層及瀝青處理底層(BTB)承載性(有效彈性模數)的掌握性極佳；整體來說，以落重式撓度儀試驗來了解路面強度，並預估其壽年，乃是一個有效而快速的方法，且其可行性應是可被認同的。

關鍵字

回彈模數 ； 靜態回算 ； 落重式撓度儀 ； 動態回算

並列摘要

The main researches in pavement engineering field in the European and American countries all take resilient modulus, MR as an index on evaluating the structure strength of the pavement and the performance. And the Falling Weight Deflection, FWD instrument can measure the deflection of the pavement directly and recalculate the MR of each layer of the pavement structure. Because of the efficiency of this testing method and can also remain the oneness of the pavement, FWD instrument is now replacing the traditional coring sample method and been wildly used on evaluating the performance and structure strength of the pavement. And this test instrument and method is very helpful to the construction to check and accep, deciding maintain tactic, and overlay pavement design.
The first FWD instrument (Dynatest 8000) was involved into the domestic by Taiwan Area National Freeway Bureau 1995, the each sense cell and entire system haven’t been calibrated or evaluate studied until now, therefore the reliability and precision of the measurement result cannot be confirmed. In this study, the calibration work of the sense cells will be done, and compare the results of dynamic backcalculation program ( DBFWD ), static backcalculation program ( WESDEF ), and the MR of the in-situ coring samples and remolded samples, in order to calibrate the general system of the FWD instrument, and also provide a confidence on the reliability of the analysis of evaluating the performance of the pavement by this instrument.
According the study results, every sense cell of the instrument still remains stable and precision with a testing procedure recommended by the manufacturer and the standard test method of ASTM D4694-96, and the absolutely calibrate of the velocity gage. And DBFWD program showed a better result of higher reliability and reasonability than WESDEF program, this program is also more suitable for investigation of the open layer of the asphalt concrete and the capacity of the BTB. General speaking, using FWD instrument to investigate the strength of the pavement and predict the life time would be a efficiency, suitable, fast method and the workability is confirmed.

並列關鍵字

Resilient Modulus ； Falling Weight Deflectometer ； Dynamic Backcaculation ； Static Backcaculation

參考文獻

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【28】 Crovetti, J. A., M. Y. Shahin, and B. E. Touma, "Comparison of Two Falling Weight Deflectometer Devices, Dynatest 8000 and KUAB 2M-FWD,"Nondestructive Testing of Pavements and Backcalculation of Moduli, ASTM STP 1026,A. J. BushⅢ,and G.Y. Baladi,Eds.,American Society for Testing and Materials,Philadelphia,pp.59-69,1989.

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