Study on Dynamic Feedback Analysis of Road Rater Measurement

• Main Authors: Horng-Yuan Chang, 張鴻源
• Other Authors: Der-Wen Chang
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/05438631710069088802

碩士 === 淡江大學 === 土木工程研究所 === 83 === Application of the Nondestructive deflection measurement becomes more pronounced in recent years for highway engineers to evaluate the structural capacity of pavements. This type of test including Road Rater, Dynaflect and Falling Weight Deflectometer is generally performed by locating a seismic source ( steady-state vibrator or transient implus ) on the pavement surface. With a series of receivers, the maximum surface deflection at various distances from receivers can be recorded. The so called deflection basin, which is an envelpoe connecting the surface displacement, is then analyzed to backcalculate structural capacity of the site; i.e., the stiffnesses of paving layers. For almost two decdes, the test was significantly improved with modern high tech in automation of data collection with high- speed electronic instruments. However, the analysis of backcalculating the layer''s stifnesses is crudely made with a static procedure ( i.e., Multilayer Elastic Theory ) inspite of its dynamic testing naturae. A number of studies showed that the wave interference in the paving systems can easily neglected by counting fully on conventional static calculation. Nevertheless, such effects on the surface deflection are somehow very significant. The object of this study is to develope a true dynamic interpretation for Road Rater test. The analysisis performed with a dynamic model based on Green''s flexibility functions and versatile iterative procedures with rational material boundaries to backfigure the pavement stiffness. The feedback algorithm as the result of this study is calibrated with both theoretical and experimental data to ensure its use in extensive cases. It is found that the dynamic backcalculation program UTAM developed in this study can provide more satisfactory results rather than the conventional programs.