The discusser emphasized that the determination of stress history of the deposit is important and that most deposits have shown some degree of overconsolidation. It is observed that making unload-reload cycles in odometer tests help to better define the maximum past consolidation pressure. It is suggested that for the determination of the shear strength where desiccation of the surface of the clay stratum has occurred at least 2 tentative values covering the probable range be used and the effects of the stability be checked for each value before selecting a design value. Often a small change in the assumed value of shear strength of the crust can have a major effect on the safety factor and therefore should be chosen with great care. Rational alternate choices of shear test methods to be used for design are discussed. Shear anisotropy is discussed and experience is described where the indications were that the average shear strength rather than the shear strength of the weaker lamina controlled stability. The importance is noted of the rate of strain in shear testing in stability analysis, and data are quoted that would indicate using a higher factor of safety for normal rate of strain shear tests. Comments are made on the stability design of embankments on soft clay deposits. Experience is described where the desicated stratum underlying deposits exhibit an overconsolidation resulting from a temporary lowering of the water table. The opinion is expressed that the soft Blue clay below El-70 is overconsolidated probably by 1 kip/sq ft - 2 kips/sq. ft.

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Filing Info

  • Accession Number: 00081412
  • Record Type: Publication
  • Report/Paper Numbers: Proc. Paper 11037
  • Files: TRIS
  • Created Date: Mar 26 1975 12:00AM