Scientific Quarterly Journal of Iranian Association of Engineering Geology

Scientific Quarterly Journal of Iranian Association of Engineering Geology

Assessing effect of mode of failure on uniaxial compressive strength of rock samples

Document Type : Original Article

Authors
Mohammad Bashir Gonbadi 1
Ali Oromiehei 2
Mohammad Reza Nikudel 3
Gholam Reza Lashkaripour 4
1 Ph.D Student of Engineering geology, Tarbiat Modares Univ.
2 P{rof. of Engineering geology Tarbiat Modares University
3 Member of Scientific board of Shahrod Univ of Tarbiat Modares Univ.
4 Member of Scientific board of Shahrod Univ of Ferdousi Univ.
Abstract
Determining the UCS of rock samples as one of the most important parameters of rock engineering is so difficult because of occurrence of so many problems. One of the most important problems  in this regard  is  the scattering  of  the  results of USC tests  and lack of  specific  criteria for  choosing  the data which represents  the strength of intact rock. Investigating the form and  the mechanism of  samples failure  through the  USC tests shows the significant  impact of  micro-fractures and microscopic discontinuities  on  the failure mode  and  also on test results.  According to the research results, that the maximum ratio of  UCS to tensile strength  and consequently  maximum  rate of USC occurs in  the simple extension failure which indicates no impact or  so weak impact  of micro-fractures on  the sample failure of this type unlike other types. In case of other extreme,  the minimum USC  ratio  to tensile  strength  and the USC belongs to  the samples  with  simple shearing failure and in this case  the failures is totally impacted by  micro-fractures. So regarding the ratio of USC to tensile strength and also considering the samples fracture mode, the real data representing the USC of intact rock could be chosen. The suitable criteria for choosing the correct data of the UCS tests is submitted in this research
Keywords
Uniaxial compressive strength
Sandstone
Mode of Failure
Micro Cracks
Shemshak Formation
Subjects
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Scientific Quarterly Journal of Iranian Association of Engineering Geology
Volume 2, Number 1 & 2
September 2009
Pages 59-72

  • Receive Date 23 September 2008
  • Revise Date 19 March 2009
  • Accept Date 26 August 2009