### Abstract

Investigation of mechanical behavior in intact rock can help to better understand the stressstrain correlation in accordance with yielding. Attention to the formulation of yield criteria can direct the research into two areas, developing the criteria based on interpolation of experimental data and detailed study of micromechanics. The aim in the mathematical theory of yielding is to describe the theoretical respects in relation to stress and strain and recognition of the limit between elastic and plastic behavior. The authors consider studying of yielding in intact rock at different scales. From Weibull theory it is believed that the increase in scale causes a decrease in the strength. This has been quantified by the Hoek-Brown equation for Uniaxial Compressive Strength (UCS). However, the confinement can change this strength and subsequently yielding. Thus, from experimental observations the change of yielding at different scales is investigated. The experiments are conducted on cylindrical samples of sandstone with diameters of 50 and 96 mm. Every specimen was tested at different confining pressures. The distinctions of the initial yield points at different scales are extracted and the yield surfaces are depicted. Finally a simple mathematical yield criterion is developed.

Original language | English |
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Title of host publication | Rock Stress and Earthquakes - Proceedings of the 5th International Symposium on In-Situ Rock Stress |

Pages | 769-776 |

Number of pages | 8 |

Publication status | Published - 2010 |

Externally published | Yes |

Event | International Symposium on In-Situ Rock Stress 2010 - Beijing, China Duration: 25 Aug 2010 → 27 Aug 2010 Conference number: 5th |

### Conference

Conference | International Symposium on In-Situ Rock Stress 2010 |
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Abbreviated title | ISRSV 2010 |

Country | China |

City | Beijing |

Period | 25/08/10 → 27/08/10 |

## Cite this

*Rock Stress and Earthquakes - Proceedings of the 5th International Symposium on In-Situ Rock Stress*(pp. 769-776)