Structural Strength Evaluation For Highway Asphalt Pavement Based On Dynamic Deflection Testing

Pavement deflection test is the basis of evaluating the carrying capacity of pavement, and is of vital importance for engineering control and inspection. The international pavement inspection and evaluating technologies have developed very fast over the past two decades, and the overall trend is:from technology of manual testing to automated testing; from damage to non-destructive technology and from general to advanced technology. The latest domestic research of LDD in Laser Dynamic Deflection Test has reached the world advanced level. While, at the same time, high technology usually requires high cost, thus it’s not been applicated into many actual engineering projects. Research concentrated on this part, therefore, is relatively less. As deflection test conducted under smart, fast, damage-free and the actual standard axle of load driving can be more superior to the traditional testing equipment, Laser Dynamic Deflectograph is the most ideal tool for deflection test. The rapid development of asphalt pavement of expressways in China in recent years, as well as the growing emphasis on road maintenance and road reconstruction have played a very good role in promoting the use and study of the laser dynamic deflectograph.As a research object as LDD is in this chapter, it first analyzed the composition and collecting principle of the LDD system, and then demonstrated the theory and method of Doppler Velocimeter, core technology of LDD, in testing the dynamic deflection of road. By presenting examples, the book showed us the calculating process of pavement deflection. At the same time, it also compared the actual use of Laser Dynamic Deflectograph and Benkelman Deflectograph, under the condition of different speed and different road structures. Then, according to characteristics of samples and data distribution of new machine, it came into conclusion that there are drawbacks to evaluate the equipment by using the existing deflection model and can hardly be able to meet the requirements. Then, according to the new testing technology and decay theory of deflection, it brought about the idea of the assessment model based on the structural level of dynamic deflection test of expressway asphalt pavement. Finally, on the basis of highway inspection projects in Hunan, that is, the Changde-Zhangjiajie highway conservation design, to make deflection assessment by using the newly advocated dynamic deflection evaluating model.