Job Well Done
DISCUSSIONS AND CLOSURES
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Discussion of “Bearing Capacity of Shallow Foundations in Anisotropic Non-Hoek-Brown Rock Masses” by Mahendra Singh and K. Seshagiri Rao
August 2005, Vol. 131, No. 8, pp. 1014–1023.
DOI: 10.1061/ ASCE 1090-0241 2005 131:8 1014
Brian C. Burman, M.ASCE1
1
Principal, Burman Consulting Pty. Ltd., 21 Telegraph Road, Pymble, Sydney NSW 2073, Australia. E-mail: brian.burman@optusnet. com.au
The discusser, having a long and abiding interest in the engineering of jointed rock masses and a particular interest in shallow foundations on rock, welcomes the paper by Singh and Rao for its explicit recognition of rock mass as a discontinuum that requires treatment as such. There are many appealing aspects of the authors’ bearing capacity analysis compared to more conventional approaches. However, the discusser is not able to accept the fourfold failure mode hypothesis, which is fundamental to their concept of bearing capacity for jointed masses. The authors have described failure modes associated with splitting, shearing, sliding, and rotation based on the results of Singh’s testing of a jointed block mass in uniaxial compression and published literature. The discusser does not have access to Singh’s data Singh 1997 but is familiar with Brown’s triaxial tests on block jointed models Brown 1970 and accepts the four failure modes under those test conditions. These failure modes would have wide acceptance throughout rock mechanics circles under general conditions. The point of difference here is that shallow foundations represent particular boundary conditions associated with a half space and, as a consequence, certain failure modes are inhibited. Just as with jointed rock slopes the more likely failure modes are slip by sliding along joints, shearing and toppling by rotation and failure by
Downloaded from ascelibrary.org by INDIAN INST OF TECHNOLOGY - ROORKEE on 03/07/13. Copyright ASCE. For personal use only; all rights reserved.
Discussion of “Bearing Capacity of Shallow Foundations in Anisotropic Non-Hoek-Brown Rock Masses” by Mahendra Singh and K. Seshagiri Rao
August 2005, Vol. 131, No. 8, pp. 1014–1023.
DOI: 10.1061/ ASCE 1090-0241 2005 131:8 1014
Brian C. Burman, M.ASCE1
1
Principal, Burman Consulting Pty. Ltd., 21 Telegraph Road, Pymble, Sydney NSW 2073, Australia. E-mail: brian.burman@optusnet. com.au
The discusser, having a long and abiding interest in the engineering of jointed rock masses and a particular interest in shallow foundations on rock, welcomes the paper by Singh and Rao for its explicit recognition of rock mass as a discontinuum that requires treatment as such. There are many appealing aspects of the authors’ bearing capacity analysis compared to more conventional approaches. However, the discusser is not able to accept the fourfold failure mode hypothesis, which is fundamental to their concept of bearing capacity for jointed masses. The authors have described failure modes associated with splitting, shearing, sliding, and rotation based on the results of Singh’s testing of a jointed block mass in uniaxial compression and published literature. The discusser does not have access to Singh’s data Singh 1997 but is familiar with Brown’s triaxial tests on block jointed models Brown 1970 and accepts the four failure modes under those test conditions. These failure modes would have wide acceptance throughout rock mechanics circles under general conditions. The point of difference here is that shallow foundations represent particular boundary conditions associated with a half space and, as a consequence, certain failure modes are inhibited. Just as with jointed rock slopes the more likely failure modes are slip by sliding along joints, shearing and toppling by rotation and failure by
References: Parkin, A. K. 1978 . “Coefficient of consolidation by the velocity method.” Geotechnique, 28 4 , 472–474. JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING © ASCE / FEBRUARY 2007 / 243 J. Geotech. Geoenviron. Eng. 2007.133:240-242.