Shear strength of cement-grout borehole plug


Akgun H.

IN SITU, vol.24, pp.107-137, 2000 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 24
  • Publication Date: 2000
  • Title of Journal : IN SITU
  • Page Numbers: pp.107-137

Abstract

The theoretical normal stress and shear strength distributions along the plug-rock interfaces of axially loaded expansive cement-grout borehole plugs cast in rock cylinders, determination of interfacial shear strength parameters, and experimental analyses of plug-rock mechanical interactions are presented as a function of uniform curing and testing temperature and of borehole size. The results of the back analysis show that the angle of internal friction along the plug-rock interface remains almost constant with increasing temperature. The cohesion slightly decreases going from ambient temperature to 70 degrees C. A pronounced reduction in cohesion occurs at 90 degrees C, which is attributed to high pore pressures and deterioration of the structural properties of the cement gel and of the cement plug-rock interface at high temperatures. In-situ experiments on larger radius plugs are recommended to assess the validity of the laboratory-scale shear strength determined in this study.