Abstract: In this paper the impact tests of soft clay have been done by using staticdynamictrue triaxial test system of modified SPAX2000. With the help of scanning electron microscope(SEM) technology, the microstructural images of the soft clay, and eight microstructural parameters including the number of pore, total area, the classification of area, total perimeter, the average diameter, the roundness, the shape coefficient and the anisotropy have been obtained. And the changes of microstructural parameters before and after impact load have been analyzed. The results show that the microstructural parameters under impact load have certain rules of change. The study can provide microscopic theory basis for dynamic drainage consolidation method of soft ground engineering design.

Key words: soft clay; triaxial test; impact load; microstructure