SEISMIC WAVE VELOCITY AS A MEANS OF IN-PLACE DENSITY MEASUREMENT, FINAL REPORT, PART I

VELOCITY-DENSITY TESTS CONDUCTED IN THE LABORATORY INVOLVED SMALL 4-INCH DIAMETER BY 4.58-INCH-LONG COMPACTED SOIL CYLINDERS MADE UP OF 3 DIFFERING SOIL TYPES AND FOR VARYING DEGREES OF DENSITY AND MOISTURE CONTENT, THE LATTER BEING VARIED WELL BEYOND OPTIMUM MOISTURE VALUES. SEVENTEEN SPECIMENS WERE TESTED, 9 WITH VELOCITY DETERMINATIONS MADE ALONG TWO ELEMENTS OF THE CYLINDER, 180 DEGREES APART, AND 8 ALONG THREE ELEMENTS, 120 DEGREES APART. SEISMIC ENERGY WAS DEVELOPED BY BLOWS OF A SMALL TACK HAMMER ON A 5/8-INCH DIAMETER STEEL BALL PLACED AT THE CENTER OF THE TOP OF THE CYLINDER, WITH THE DETECTOR PLACED SUCCESSIVELY AT FOUR POINTS SPACED 1/2-INCH APART ON THE SIDE OF THE SPECIMEN INVOLVING WAVE TRAVEL PATHS VARYING FROM 3.36 INCHES TO 4.66 INCHES IN LENGTH. TIME INTERVALS WERE MEASURED USING A MODEL 217 MICRO-SEISMIC TIMER IN BOTH LABOATORY AND FIELD MEASUREMENTS. FORTY BLOWS OF THE HAMMER WERE REQUIRED FOR EACH VELOCITY DETERMINATION, WHICH AMOUNTED TO 80 BLOWS ON 9 LABORATORY SPECIMENS AND 120 BLOWS ON THE REMAINING 8 CYLINDERS. THIRTY-FIVE FIELD TESTS WERE MADE OVER THE THREE SELECTED SOIL TYPES, ALL FINE-GRAINED, USING A 2-FOOT SEISMIC LINE WITH HAMMER-IMPACT POINTS AT 6-INCH INTERVALS. THE SMALL TACK HAMMER AND 5/8-INCH STEEL BALL WAS, AGAIN, USED TO DEVELOP SEISMIC WAVE ENERGY. GENERALLY, THE DENSITIES OBTAINED FROM THE VELOCITY MEASUREMENTS WERE LOWER THAN THOSE MEASURED IN THE CONVENTIONAL FIELD TESTING. CONCLUSIONS WERE REACHED THAT: (1) THE METHOD DOES NOT APPEAR TO BE USABLE FOR MEASUREMENT OF DENSITY OF ESSENTIALLY FINE-GRAINED SOILS WHEN THE MOISTURE CONTENT GREATLY EXCEEDS THE OPTIMUM FOR COMPACTION, AND (2) DUE TO A GRADUAL REDUCTION IN VELOCITY UPON AGING, APPARENTLY BECAUSE OF GRADUAL ABSORPTION OF PORE WATER INTO THE EXPANDABLE INTERLAYER REGION OF THE CLAY, THE SEISMIC TEST SHOULD BE CONDUCTED IMMEDIATELY AFTER SOIL COMPACTION TO OBTAIN A MEANINGFUL VELOCITY VALUE. /BPR/

  • Supplemental Notes:
    • Hpr-1(5), HR-114
  • Corporate Authors:

    Iowa State University, Ames

    2711 South Loop Drive
    Suite 4700
    Ames, IA  United States  50010-8664

    Iowa State Highway Commission

    800 Lincoln Way
    Ames, IA  United States  50010

    Bureau of Public Roads /US

    400 7th Street, SW
    Washington, DC  United States  20590
  • Authors:
    • Hogan, J M
    • Handy, R L
  • Publication Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 00228643
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS, STATEDOT
  • Created Date: Aug 15 2004 2:08AM