CRACK INITIATION AND PROPAGATION IN ROCK

Theories of crack initiation, propagation and bifurcation in perfect solids based on energy equilibrium criteria, elasticity theory considerations and particulate body mechanics are reviewed. Modifications of these and their applicability to rock are discussed. Different testing methods used to study the fracture characteristics of rock are reviewed; a bending method was chosen as most suitable for the purpose. A literature review on the effect of heat treatments on rock weakening are discussed. The principles of a continuous duty, high powered gas laser as a heat source are described. The values of the fracture surface energy were determined for four different geometries of a granite specimen; the results show that if a stable fracture is obtained, the value is independent of geometry. Results of the heat treatment and laser treatment studies on marble and granite show the thermal exposure causes a decrease in the value of ultimate flexural strength because of intergranular and transgranular cracks induced in the specimen. (Author)

• Corporate Authors:

  Massachusetts Institute of Technology

  Department of Civil Engineering, 77 Massachusetts Avenue
  Cambridge, MA  United States  02139
• Authors:
  • Forootan-Rad, P
  • Moavenzadeh, F
• Publication Date: 1968-5

Media Info

• Pagination: 127 p.

Subject/Index Terms

• TRT Terms: Excavating equipment; Intelligent transportation systems; Mining; Tunnels
• Old TRIS Terms: Advanced systems
• Subject Areas: Bridges and other structures; Operations and Traffic Management; Railroads;

Filing Info

• Accession Number: 00039108
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: R68-29 Res Rpt
• Contract Numbers: C-85-65t
• Files: TRIS
• Created Date: Nov 24 1973 12:00AM