Abstract: The dynamic deflection was calculated with the spectral element method, and the results were compared with the static deflection that was obtained from the layered elastic theory. The acceptance deflections of 5 engineering sections were computed using dynamic, static methods and the specification method of JTG D50—2017, respectively, and the results were compared with the field measured deflections. The results show that under the effect of falling weight deflectometer (FWD) load, the static deflections of pavement structures are greater than the dynamic deflections; the gap between the dynamic and static deflections increases with the increase of asphalt layer thickness, the decrease of subgrade modulus and the increase of distances between the sensors and the loading center, and asphalt pavements dynamic effects are more obvious. The ignorance of the effects of FWD load will lead to a larger acceptance deflection. The static acceptance deflection can be nearly 4 times of the measured deflection, which extends the acceptance criteria to a certain extent. While the dynamic deflection is only about 1.5 times of the measured deflection, and the dynamic method can more effectively control the pavement construction quality. The adjustment coefficient of the subgrade modulus in JTG D50—2017 unexpectedly increases the differences between the theoretical and measured deflections, so its validity remains to be discussed.

Key words: road engineering, falling weight deflectometer, acceptance deflection, dynamic effect