Technical Reports

Rock Fracture Research- Surfactants

  • 01
  • Jan
  • 1973
AUTHOR: F.J. McGarry, F. Maovenzadeh
OFFICE: RPD
REPORT NUMBER: FRA-RT-73-22
SUBJECT: Evaluation
KEYWORDS: Tunneling, Rock Fracture, Sufactants
ABSTRACT: In order to reduce the resistance of hard rocks to excavation by available cutters, and in order to reduce wear on cutters and thus to increase the efficiency of conventional tunneling machines and thus improve their rate of advance in hard rocks, surface active agents have been studied in controlled laboratory environments and have been experimented with in the field in actual tunneling operations. The laboratory study utilized a notched beam test to measure the effectiveness of thirty different surface active agents on the amount of surface energy required to cause stable fracture in rock specimens. In addition to the type of rocks, geometry of the specimens, type of surface active agents, the effect of environment such as temperature and degree of saturations were studied. The principal mechanism responsible for weakening of rocks in the presence of surface active agents was believed to be that of stress activated corrosion. The application of surfactants in the laboratory resulted in a reduction of up to fifty percent in rock strength, while limited experiments in the field have shown a 10 to 20 percent increase in the rate of advance. Substantial efforts both in the laboratory and in the field are needed to fully understand the mechanisms involved and to utilize the effectiveness of surfactants as weakening agents for hard rocks.

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