WATERWAYS EXPERIMENT STATION LARGE TRIAXIAL APPARATUS

A LARGE TRIAXIAL APPARATUS WAS DEVELOPED IN CONNECTION WITH STUDIES OF THE DISTRIBUTION OF STRESSES AND STRAINS IN SOIL MASSES. THE APPARATUS WAS BUILT TO PROVIDE A SUBSTANTIALLY KNOWN STRESS CONDITION IN A MASS OF SAND. THIS WAS NEEDED IN CONNECTION WITH THE STUDY OF PRESSURE CELL ACTION. DETAILS OF THE LARGE TRIAXIAL APPARATUS AND ITS OPERATION AND USE ARE DESCRIBED. IT WAS FOUND THAT CONSIDERABLE VARIATION EXISTS BETWEEN MAGNITUDES OF STRESSES AT VARIOUS POINTS WITHIN A TRIAXIALLY LOADED SAND MASS: (1) AT MID-HEIGHT, VERTICAL STRESSES NEAR THE CENTER ARE APPRECIABLY GREATER THAN THOSE AT THE EDGE OF THE SPECIMEN, AND (2) NEAR THE HEAD AND BASE PLATES, VERTICAL STRESSES NEAR THE CENTER ARE APPRECIABLY LOWER THAN THOSE AT THE EDGE OF THE SPECIMEN. CONSIDERABLE VARIATION EXISTS BETWEEN MAGNITUDES OF STRAINS AT VARIOUS POINTS WITHIN A TRIAXIALLY LOADED SAND MASS. VERTICAL STRAINS IN THE CENTER OF THE SPECIMEN MAY BE SEVERAL TIMES AS LARGE AT MID-HEIGHT AS NEAR THE TOP AND BOTTOM. THE PRESSURE CELL RESULTS INDICATE NO EFFECT OF DENSITY ON THE DISTRIBUTION OF STRESSES THROUGHOUT THE SPECIMEN. SINCE THE PRESSURE CELLS WERE STIFFER THAN THE SURROUNDING SOIL, THEY MIGHT BE EXPECTED TO YIELD READINGS SOMEWHAT TOO LARGE. IN COMPARING RESULTS FROM THE LARGE APPARATUS AND EQUIVALENT SMALL TESTS, THE FOLLOWING TRENDS WERE NOTED: (1) LARGE SPECIMENS SHOWED AVERAGE VERTICAL STRAINS LESS THAN THOSE FOR THE SMALL LABORATORY SPECIMENS WHEN SUBJECTED TO THE SAME EXTERNAL STRESSES, (2) THE SLOPES OF STRESS-STRAIN CURVES WERE GREATER FOR THE LARGE SPECIMENS, AND (3) THE ANGLE OF INTERNAL FRICTION FOR THE DRY SAND WHEN DETERMINED FROM LARGE TRIAXIAL SPECIMENS WAS GENERALLY ABOUT A DEGREE LARGER THAN WHEN DETERMINED FROM THE SMALL LABORATORY SPECIMENS.

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  • English

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  • Accession Number: 00229625
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 15 2004 2:39AM