VIBRATORY AND SLOW REPETITIONAL LOADING OF SOILS

CONTROLLED STRESS SMALL SCALE PLUNGER TESTS ON TWO TYPES OF CLAY AND UNCONFINED COMPRESSIVE STRENGTH TESTS PERFORMED ON ONE CLAY UNDER BOTH STATIC AND VIBRATORY CONDITIONS INDICATED THAT FOR THE SOILS TESTED THE DEFORMATION PRODUCING CAPACITY OF A VIBRATORY FORCE WAS NO GREATER THAN THAT OF AN EQUIVALENT STATIC FORCE SO LONG AS THERE WAS NO RESONANCE OF THE VIBRATOR-SOIL SYSTEM. COMPARISON OF STATIC AND VIBRATORY CONSOLIDATION TEST RESULTS ON THREE TYPES OF CLAY SUPPORTED THIS FINDING. PREVIOUSLY REPORTED PLUNGER TESTS ON A WELL GRADED SAND HAD SHOWN THAT THE SAND WAS VERY SENSITIVE TO THE ACTION OF VIBRATORY FORCES. FURTHER TEST RESULTS OBTAINED ON A UNIFORM POORLY GRADED BEACH SAND ARE NOW PRESENTED. THIS SAND WAS FOUND TO BE EVEN MORE SENSITIVE TO VIBRATORY FORCES WHICH PRODUCED UP TO 140 TIMES GREATER PLUNGER PENETRATIONS THAN THE PENETRATIONS PRODUCED BY EQUIVALENT STATIC FORCES. THIS WAS STILL THE CASE WHEN THE VIBRATORY FORCE WAS VERY SMALL AND DID NOT EXCEED PLUS OR MINUS 2.0 PERCENT OF THE ORIGINAL STATIC LOAD, EVEN THOUGH THIS LOAD WAS FIRST REDUCED BY SOME 15 PERCENT TO SIMULATE LOAD REDISTRIBUTION BETWEEN WHEELS SUCH AS TAKES PLACE DURING ENGINE WARM-UP OF AIRPLANES IN THE FIELD. TESTS WITH SAND-CLAY MIXTURES INDICATED THAT THE RESISTANCE TO VIBRATORY FORCES OF SANDS COULD WELL BE IMPROVED BY THE ADDITION OF CLAY. A SERIES OF SLOW REPETITIONAL PLUNGER LOAD TESTS WAS PERFORMED ON SANDS AND ON A CLAY WITH A SPECIALLY DESIGNED MACHINE. THE RESULTS SHOWED THAT, SO LONG AS NO RESONANCE OF THE VIBRATOR-SOIL SYSTEM OCCURRED, THE FREQUENCY OF LOAD REPETITION WAS OF NO IMPORTANCE. IDENTICAL PLUNGER PENETRATIONS WERE OBTAINED FOR THE SAME NUMBER OF LOAD REPETITIONS IRRESPECTIVE OF WHETHER THE TEST WAS PERFORMED AT ONE CYCLE PER MIN OR AT 1500 CYCLES PER MIN. FOR THE SAME NUMBER OF LOAD REPETITIONS ON SAND, PLUNGER PENETRATIONS INCREASED WITH THE INTENSITY OF THE SLOW REPETITIONAL OR VIBRATORY LOAD. FOR THE SAME FRACTIONAL VALUE OF THE SLOW REPETITIONAL OR VIBRATORY FORCE EXPRESSED AS A FRACTION OF THE ORIGINAL LOAD, THE PLUNGER PENETRATIONS NATURALLY INCREASED ALSO WITH THE VALUE OF THE ORIGINAL LOAD. HOWEVER, A SLOW REPETITIONAL FORCE OF THE SAME INTENSITY WAS FOUND TO PRODUCE SOMEWHAT HIGHER PENETRATIONS WITH A DECREASE OF THE INTENSITY OF THE ORIGINAL STATIC LOAD. A PREVIOUSLY OBSERVED RAPID INCREASE OF BOTH STATIC AND DYNAMIC PLUNGER PENETRATIONS WHEN THE SAND WAS BELOW A CERTAIN DENSITY, WAS NOW RELATED BY MEANS OF TRIAXIAL SHEAR TESTS TO THE SO-CALLED "CRITICAL DENSITY." MENTION IS MADE OF THE RESULTS OF TWO SUPPLEMENTARY INVESTIGATIONS PERFORMED FOR THE PROJECT. /AUTHOR/

  • Supplemental Notes:
    • Vol 26, pp 551-562, 31 FIG, 9 REF
  • Authors:
    • Tschebotarioff, G P
    • Mcalpin, G W
  • Publication Date: 1947

Media Info

  • Monograph Title: Proceedings of the Twenty-Sixth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 5-8, 1946
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00233096
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 22 1972 12:00AM