Abstract: In order to investigate the dynamic properties and energy dissipation of loess under passive confining pressure condition, a Φ100 mm split Hopkinson pressure bar (SHPB) apparatus was used to conduct dynamic compression tests on loess samples with different initial densities at different impact speeds. The validity of the experiment was verified by considering the stress equilibrium and constant strain rate, the dynamic stress-strain curve and absorbed energy time history curve of the loess sample were obtained. Experimental results show that when the strain rate is in the range of 330～620 s?1, the yield strength of the loess sample with the initial density of 1.7 g/cm3 and the moisture content of 4.45% is less affected by the strain rate, and the strain rate effect is not obvious. When the strain rate is about 445 s?1, the yield strength, dynamic peak stress and specific energy absorption of the loess sample with a moisture content of 3.77% increase with the increase of the initial density of the sample. In the incident energy range of 1 700～5 500 J, the energy dissipation rate of the loess sample with the initial density of 1.7 g/cm3 and the moisture content of 4.45% is about 27%, and the specific energy absorption increases with the increase of incident energy. The test results can provide technical reference for the construction and protection of military and civil engineering construction related to loess.

Key words: loess, SHPB, dynamic mechanical properties, energy dissipation, strain rate, density