To study the dynamic response characteristics of soil under impact load

flat dynamic load tests (FDLT) with different load levels and loading rates were carried out on two typical soils (sand and clay) in Guangzhou University Town by using the self-developed additional excitation force-type FDLT system

obtaining three characteristic curves of load-time curve

displacement-time curve

and load-displacement curve

establishing the empirical formula of dynamic deformation modulus and loading rate

and comparing the effects of loading rate of the two soils under impact load. It shows that: (1) There is a threshold of charging voltage in the FDLT test of sand. During the impact test on this threshold

the loading rate has a great effect on the dynamic strength and deformation of sand

while it has no obvious effect on clay under the same conditions. (2) The same point of the loading rate on the displacement response of clay and sand is that the maximum load and maximum displacement of the two soils both increase with the increase of loading rate. The difference is that the time for clay to reach the peak displacement increases with the increase of loading rate while the time for sand to reach the peak displacement shows a pattern of increasing and then decreasing with the increase of loading rate. (3) The dynamic deformation modulus varies logarithmically with the loading rate. The results can provide a reference for soil dynamic characteristics study

dynamic and static parameter conversion and engineering design.