Stress concentration at the bottom of a borehole and its effect on borehole breakout formation

T. Ito, K. Kurosawa, Kazuo Hayashi

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Stress concentration at the bottom of a borehole due to the corners with small radius of curvature in an axial section and its effect on the azimuth of breakout was studied. To this end, a 3-D finite element analysis was conducted and the stress around the borehole was examined for boreholes arbitrarily oriented to three principal axes of remote stress. Results show that, in the case of high strength rock, compressive failure resulting in spalling of a borehole may occur only at the bottom of the borehole. The spalling can occur continuously with drilling, and results in continuous spalling with depth, i.e., a breakout. This type of breakout tends to form on one side of the borehole and its orientation is approximately perpendicular to the orientation of standard breakouts, inferred from the stress concentration due to the cylindrical shape of the borehole.

Original languageEnglish
Pages (from-to)153-168
Number of pages16
JournalRock Mechanics and Rock Engineering
Volume31
Issue number3
DOIs
Publication statusPublished - 1998 Jan 1

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Geotechnical Engineering and Engineering Geology
  • Geology

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