Considering the effect of discontinuities in prediction of end bearing capacity of rock socketed shafts

Research output: Contribution to conferencePaperpeer-review

Abstract

For optimal design of rock-socketed shafts used to support axial loading, the end bearing resistance should be considered. The existing empirical methods for determining the end bearing capacity qmax of rock-socketed shafts use empirical relations between qmax and the unconfined compressive strength of intact rock, σc. Since rock-socketed shafts are supported by the rock mass (both intact rock blocks and discontinuities separating them) not just by the intact rock, one should consider not only the intact rock properties but also the influence of discontinuities when determining qmax. In this paper, a database consisting of 25 test shafts with RQD (rock quality designation) value available is developed. Using the developed database, a new empirical relation between qmax and the unconfined compressive strength of rock mass, σcm, is derived. The new empirical relation explicitly considers the effect of discontinuities by using σcm, which is directly related to RQD. Finally, an example is presented to show the application of the newly derived empirical relation. The results indicate that the new empirical relation between qmax and σcm provides more accurate prediction of qmax than the old empirical relations between qmax and σc.

Original languageEnglish (US)
StatePublished - 2009
EventISRM International Symposium on Rock Mechanics 2009, SINOROCK 2009 - Hong Kong, China
Duration: May 19 2009May 22 2009

Conference

ConferenceISRM International Symposium on Rock Mechanics 2009, SINOROCK 2009
Country/TerritoryChina
CityHong Kong
Period5/19/095/22/09

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

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