ROCK BREAKAGE BY PELLET IMPACT

This report discusses a study of rock breakage effected by the use of high-speed pellets. A previous study had been conducted at IITRI in which two rock types were subjected to hypervelocity impact by solid Zelux pellets as well as hollow, water-filled capsules. In this extension to the above study 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/square meter to 30 MN/square meter (56,900 psi to 4,400 psi). Other mechanical properties of the rocks were also determined. The pellets used in this study were solid cylinders 5.6 mm in diameter and 1 cm long, weighing nearly 0.25 gm. Impact velocities of 1 to 7 km/sec were generated by means of a rifle and a light-gas gun. Craters with volumes ranging from almost negligible values to 52 cc 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 were obtained when these ratios were near 100. For the stronger rocks this implied impact velocities above 5 km/sec. The dominant rock failure mechanism appears to be spalling. (Author)

• Corporate Authors:

  IIT Research Institute

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

Media Info

• Pagination: 92 p.

Subject/Index Terms

• TRT Terms: Dolomite; Gabbro; Granite; Limestone; Physical properties; Rock mechanics; Rocks; Sandstones; Tests
• Old TRIS Terms: Dolomite (Rock); Rock properties; Rock tests
• Subject Areas: Geotechnology; Railroads;

Filing Info

• Accession Number: 00039188
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: Final Rpt
• Contract Numbers: DOT-3-0171
• Files: TRIS
• Created Date: Nov 24 1973 12:00AM