ANALYSIS OF FILTER REQUIREMENTS FOR COMPACTED CLAYS

IT IS RECOGNIZED THAT CONVENTIONAL FILTER DESIGN CRITERIA, BASED ON GRAIN SIZE, WHEN APPLIED TO COHESIVE SOILS, MAY RESULT IN UNECONOMICAL DESIGN. THEORETICAL AND EXPERIMENTAL STUDIES ON THE SELECTION OF SUITABLE FILTER MATERIALS FOR FAT CLAY HAVE BEEN CONDUCTED IN ISRAEL DURING THE LAST DECADE. THE PAPER REPORTS RECENT STUDIES MADE ON MODELS OF COMPACTED CLAY PLACED IN CONTACT WITH ACTUAL FILTER MATERIAL, AS WELL AS WITH BASES WITH HOLES SIMULATING FILTER MATERIAL, AND SUBJECTED TO CONTROLLED FLOW OF WATER. TESTING CONDITIONS INCLUDED VARIATION OF PRESSURE ON THE CLAY, AND OF THE SIZE OF HOLES WITHIN THE BASES AND GRADIENTS. WHEN FAILURE TOOK PLACE THE GRADIENT WAS NOTED AND THE SHEAR STRENGTH OF THE CLAY WAS DETERMINED. THE EXPERIMENTAL RESULTS SHOW THAT A FAT CLAY MAY BE PROTECTED BY A FAIRLY COARSE FILTER MATERIAL. RELATIVELY HIGH AVERAGE GRADIENTS WERE REQUIRED TO CAUSE FAILURE EVEN WHEN THE CLAY WAS ALLOWED TO SWELL UNDER ZERO PRESSURE. A FAIRLY REASONABLE AGREEMENT WAS FOUND BETWEEN THE EXPERIMENTAL RESULTS AND A THEORY CORRELATING THE SIZE OF CLAY AGGREGATE WASHED OUT, THE EXIT GRADIENTS, AND THE TENSILE STRENGTH OF THE CLAY AT FAILURE. /LCPC/RRL/A/

Subject/Index Terms

Filing Info

  • Accession Number: 00234573
  • Record Type: Publication
  • Source Agency: Road Research Laboratory /UK
  • Files: TRIS
  • Created Date: Oct 7 1994 12:00AM