PERMEABILITY OF COHESIONLESS SOILS

Experimental work is described which was designed to bring out the effects of the uniformity coefficient, U, and the grain effective diameter, D10, on the permeability of the porous matrix. The concept of tortuosity can be explained best in terms of factors U, D10, void ratio e, and a shape factor. An equation representing permeability that is given in textbooks is presented, and an attempt is made to modify this by taking into account the effective diameter, D10, as proposed by Terzaghi and others. Details are given of the preparation of 36 samples (divided into 4 groups) taken from the matrix of natural sand and gravelly sand soils to study the effect of U and E on permeability. The hydraulic conductivity, K, was measured experimentally for the prepared samples at different degrees of compaction. The measured values of K do not yield to direct analysis and adjustments were inevitable. The experimental results are presented and analyzed. The conclusions drawn from the study emphasizes the dependability of hydraulic conductivity on U, D10 and void ratio E. The factor alpha, which includes the shape effect, is related to the effective diameter, D10, and is found to be independent of void ratio for cohesionless soils. An empirical equation is presented which includes available factors affecting permeability and it is recommended that it be applied for determining permeability for cohesionless soils. An expression for tortuosity is also obtained in terms of U and D10.

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  • Accession Number: 00080831
  • Record Type: Publication
  • Report/Paper Numbers: Proc. Paper 10981 Tech. Note
  • Files: TRIS
  • Created Date: Mar 6 1975 12:00AM