ROCK BREAKAGE BY PELLET IMPACT

A PREVIOUS STUDY HAD BEEN CONDUCTED IN WHICH TWO ROCK TYPES WERE SUBJECTED TO HYPERVELOCITY IMPACT BY SOLID ZELUX PELLETS AS WELL AS HOLLOW, WATER-FILLED CAPSULES. IN ADDITION SIX ROCK TYPES, VIZ. FRENCH CREEK GABBRO, MILFORD PINK GRANITE, CONNECTICUT BROWNSTONE, MINNESOTA DOLOMITE, INDIANA LIMESTONE, AND MASSILLON SANDSTONE, WERE INVESTIGATED. THE COMPRESSIVE STRENGTHS OF THESE ROCKS RANGE FROM 390 MN/M SQUARE TO 30 MN/M SQUARE (56,900 PSI TO 4,400 PSI). OTHER PROPERTIES OF THE ROCKS WERE ALSO DETERMINED. THE PELLETS USED WERE SOLID CYLINDERS 5.6 MM (0.22 IN.) IN DIAMETER AND 6 CM (0.4 IN.) LONG, WEIGHTING NEARLY 0.25 GM (0.56 X 10-3 LB). IMPACT VELOCITIES OF 1 TO 7 KM/SEC (3,300 TO 23,000 FPS) WERE GENERATED BY MEANS OF A RIFLE AND A LIGHT-GAS GUN. CRATERS WITH VOLUMES RANGING FROM ALMOST NEGLIGIBLE VALUES TO 52 CC (3.2 CU IN.) WERE OBTAINED. REGRESSION EQUATIONS FOR CRATER VOLUME AND CRATER DEPTH IN TERMS OF THE IMPACT PARAMETERS AND ROCK PROPERTIES WERE DETERMINED. IMPACT PRESSURES/COMPRESSIVE STRENGTH RATIOS OF UP TO NEARLY 1000, WITH THE WEAKER ROCKS, WERE OBTAINED. IT WAS FOUND THAT SPECIFIC ENERGY CONSUMPTIONS OF THE ORDER OF 200 JOULES/CC (2,400 FT-LB /CU IN.) WERE OBTAINED WHEN THESE RATIOS WERE NEAR 100. FOR THE STRONGER ROCKS THIS IMPLIED IMPACT VELOCITIES ABOVE 5 KM/SEC (16,500 FPS). THE DOMINANT ROCK FAILURE MECHANISM APPEARS TO BE SPALLING. /AUTHOR/

  • Supplemental Notes:
    • Final Rpt NO D6000-10, RPT NO FRA-RT-70-29, 85 PP, 58 FIG, 4
  • Corporate Authors:

    IIT Research Institute

    10 West 35th Street
    Chicago, IL  USA  60616
  • Authors:
    • Singh, M M
  • Publication Date: 1969-12-24

Subject/Index Terms

Filing Info

  • Accession Number: 00215450
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Dec 6 1971 12:00AM