THEORY FOR SHEAR STRENGTH OF GRANULAR MATERIALS--DISCUSSION

The authors rightly observed that there are different empirical correlations available between the average number of contacts per particle, N and void ratio e, or the porosity, n, of the collection of particles. However, other investigators have noted the relationship Nn equals 3.1. or the relationship Nn equals 3 (the latter applying to the packing of glass spheres) rather than that porosed by the authors, which is in considerable error for material with low porosity. If the equation given by the authors is used, the limiting angle is more realistic. The behavior of glass spheres in the triaxial test has been investigated to study the types of motion that the particles undergo during shearing. The results indicated that sliding predominates at the upper and lower surfaces of the specimen (against the end plates) and in these regions rotation is at a minimum. Also rotation was found to be far more likely to occur at the curved surface of the specimen than within its interior. These results may point to the inadequacy of the triaxial test to separate the components of the shear strength of particulate media as was done by the authors. The difference in the mode of the particles in the different parts of the sample in the triaxial test may mask the true mechanical behavior completely.

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  • Accession Number: 00178883
  • Record Type: Publication
  • Report/Paper Numbers: ASCE 13838 Proceeding
  • Files: TRIS
  • Created Date: Sep 27 1978 12:00AM