Triaxial tests under high loading rates and different confining pressures simulate the multi-pass effect of a tractor wheel loading on the soil. A volume measuring technique was developed to be used in triaxial tests conducted under high loading rates.

A sandy clay agricultural soil was tested under predetermined conditions using an INSTRON loading frame, a differential pressure transducer and an APPLE Il + microcomputer. A preliminary analysis indicated that the measuring technique that was developed, was capable of recording volume changes under high loading rates. Stress-density plots were created using the obtained data and a mathematical model was developed relating stress to density. Stress-strain data was used to evaluate the soil parameters under the Mohr-Coulomb failure criteria. Furthermore, the influence of the initial soil density on the soil behavior was evaluated and subsequently compared to the results of a similar study conducted under a different initial density.