STRESS-DEFORMATION AND STRENGTH CHARACTERISTICS OF A COMPACTED SHALE

When shales are encountered in road cuts, economic and environmental considerations usually dictate that they be used in adjoining embankments. However, unless special precautions are taken, the stability of a shale embankment can deteriorate with time on account of the nondurable nature of most shales. Previous investigators have developed various tests to classify shales with respect to their hardness, durability and degradability. This paper presents the results of a laboratory investigation to define the effective stress strength parameters of mechanically hard but nondurable shale pieces of a lower Mississippian age formation (new Providence) from the state of Indiana, USA. The initial gradation of crushed shale aggregate, the molding water content, the compaction pressure, and the pre-shear consolidation pressure were adopted as the independent test variables. Triaxial specimens formed by kneading compaction were back pressure saturated under a low effective confining pressure, consolidated to the desired isotropic effective stress, and sheared undrained at a constant rate of deformation. The compaction characteristics, the volume changes during saturation and consolidation, and the undrained shearing response including pore water pressure changes were studied. The effective stress strength parameters evaluated at maximum deviator stress were found to be essentially independent of the initial conditions, except for loose uncompacted aggregate. The compaction characteristics, the volume change characteristics, the induced pore water pressure changes, and the consolidated undrained strength were found to be greatly dependent on the initial conditions. (TRRL)

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 1-14

Subject/Index Terms

Filing Info

  • Accession Number: 00311812
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0-7277-0069-3
  • Files: ITRD, TRIS
  • Created Date: Nov 19 1980 12:00AM