Comparison of strain-rate dependent stress-strain behavior from Ko-consolidated compression and extension tests on natural Hong Kong Marine deposits

Jianhua Yin, Chun Man Cheng

Research output: Journal article publicationJournal articleAcademic researchpeer-review

29 Citations (Scopus)

Abstract

This article presents results from a series of Ko-consolidated compression and extension triaxial tests on specimens from undisturbed samples of Hong Kong Marine Deposits (HKMD). To investigate the strain-rate effects, a total of seven Ko-consolidated triaxial tests were conducted including four compression tests and three extension tests. After Ko-consolidation, the triaxial test specimens were sheared at step-changed axial strain rates under three different confining pressures of 50 kPa, 150 kPa, and 400 kPa, respectively. The step-changed strain rates were applied in the following order: +2%/h, +0.2%/h, +20%/h, -2%/h (unloading) and +2%/h (reloading) for the four compression tests and -2%/h, -0.2%/h, -20%/h, +2%/h (unloading) and -2%/h (reloading) for the three extension tests. The results are reported and analyzed in the paper. The results show that the strain rate effects, the stress-strain characteristics, and the effective stress paths of the specimens for tests in a compression state are different from those for tests in an extension stage. One order of magnitude increase in axial strain rate causes an average 8.6% increase in undrained shear strength for compression tests and a 12.1% increase for extension tests. It is also found that the failure mode of the specimens in compression is different from that in extension. The stress-strain behavior of specimens shows strain-softening and a clear shear band in compression tests, but strain-hardening without any clear shear band in extension tests for the same absolute value of axial strain.
Original languageEnglish
Pages (from-to)119-147
Number of pages29
JournalMarine Georesources and Geotechnology
Volume24
Issue number2
DOIs
Publication statusPublished - 1 Apr 2006

Keywords

  • K -consolidation o
  • Marine deposits
  • Shear banding
  • Strain-rate effects
  • Triaxial compression
  • Triaxial extension

ASJC Scopus subject areas

  • Oceanography
  • Geotechnical Engineering and Engineering Geology
  • Ocean Engineering

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