DISCUSSION OF FUNDAMENTAL ASPECTS OF ELECTO-OSMOSIS IN SOILS

CASAGRANDE IS OF THE OPINION THAT THE AUTHORS MADE AN IMPORTANT CONTRIBUTION TO THEORETICAL KNOWLEDGE OF ELECTRO-OSMOTIC WATER TRANSPORT IN SOILS. HE POINTS OUT THAT THE COEFFICIENT OF ELECTRO-OSMOTIC PERMEABILITY CHANGES DIRECTLY WITH THE POROSITY OF THE SOIL AND SINCE THE POROSITY IN WHICH THE VOID RATIO RANGES WITHIN RELATIVELY NARROW LIMITS EVEN FOR EXTREME SOILS, THE VARIATION OF THE OSMOTIC PERMEABILITY FOR SOILS HAVING LOW TO MEDIUM PLASTICITY SHOULD BE RATHER SMALL. FROM HELMHOLTZ' EQUATION IT IS OBVIOUS THAT THE COEFFICIENT OF ELECTRO-OSMOTIC PERMEABILITY IS ALSO AFFECTED BY VARIATIONS IN THE ZETA-POTENTIAL. HOWEVER, IN THE NUMEROUS NATURAL SOILS INVESTIGATED BY THE WRITER, THERE HAS SO FAR BEEN NO SINGLE CASE IN WHICH THE COEFFICIENT OF ELECTRO-OSMOTIC PERMEABILITY APPEARS TO HAVE BEEN GREATLY INFLUENCED BY THE ZETA-POTENTIAL. WHILE IN A RIGID CAPILLARY BODY ELECTRO-OSMOTIC DISCHARGE CAN OCCUR IN AN OPEN SYSTEM WITH UNINHIBITED PORE WATER REPLENISHMENT, IN COMPRESSIBLE SOILS ELECTRO-OSMOSIS IS EFFECTIVE IN BOTH OPEN AND CLOSED SYSTEMS. ELECTRO-OSMOSIS IN A CLOSED SYSTEM SIMPLY REMOVES PART OF THE PORE WATER, CAUSING THE SOIL TO SHRINK. LABORATORY TESTS CONDUCTED IN CONNECTION WITH PRACTICAL APPLICATIONS OF ELECTRO-OSMOSIS SHOULD BE ARRANGED AS CLOSED SYSTEMS. THE IMPORTANCE IS STRESSED BY THE AUTHORS OF THE ELECTRO-OSMOTIC TRANSPORT WHICH BASICALLY DETERMINES THE EFFICIENCY OF THE SYSTEM. THE WRITER'S EXPERIENCE IN ELECTRO-OSMOTIC STABILIZATION PROJECTS INDICATES THE ORDER OF MAGNITUDE OF THE ELECTRO-OSMOTIC TRANSPORT IS ONLY OF SECONDARY IMPORTANCE. THE WRITER BELIEVES THAT GRAPHICAL REPRESENTATIONS OF ELECTRO-OSMOTIC PERMEABILITY VERSUS POROSITY ARE MORE SIGNIFICANT THAN PLOTS OF PERMEABILITY VERSUS WATER CONTENT. REFERENCES: FUNDAMENTAL ASPECTS OF ELECTRO-OSMOSIS IN SOILS, D. H. GRAY, J. K. MITCHELL, JOURNAL OF THE SOIL MECHANICS AND FOUNDATIONS DIVISION, PROCEEDINGS OF THE AMERICAN SOCIETY OF CIVIL ENGINEERS, PROCEEDINGS PAPER 5580, NOVEMBER 1967.

  • Supplemental Notes:
    • Vol 94, No SM 6, PP 1385-1393, 2 TAB, 15 REF
  • Authors:
    • Casagrande, L
    • Bally, R L
    • Antonescu, I P
    • Esrig, M I
    • Long, R P
  • Publication Date: 1968-11

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  • Accession Number: 00237733
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 26 1994 12:00AM