The CRREL Instrumented Vehicle (CIV), shear annulus, direct shear, and triaxial compression devices were used to characterize the strength of thawed and thawing soil. These strength values can be used in simple traction models to predict the tractive performance of vehicles. Strength was evaluated in terms of the parameters cohesion (c') and internal angle of friction (phi') based on the Mohr-Coulomb failure criterion. It is proposed here that an instrumented vehicle is best suited for terrain characterization for mobility studies because the conditions created by a tire slipping on a soil surface are exactly duplicated. The c' and phi' values from the shear annulus were found to overpredict traction because of the low normal stress applied by the annulus and the curved nature of the failure envelope. Of all the tests, the direct shear test yielded the highest phi' value, most likely because the test was run at a slow deformation rate under drained conditions. The triaxial test results were the most similar to those from the vehicle. All test methods show phi' increasing with soil moisture up to the liquid limit of the soil and then decreasing. As measured with the vehicle, phi' was also found to be strongly influenced by the thaw depth.


  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 17 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00625395
  • Record Type: Publication
  • Report/Paper Numbers: CRREL Report 92-17
  • Files: TRIS
  • Created Date: Nov 24 1993 12:00AM