Critical state behaviour of weakly bonded soil in drained state

ABSTRACT

A series of consolidated drained triaxial test was performed on weakly bonded soils that were artificially prepared by mixing sand (87%) and kaolin (13%). To create weakly bond strength, samples were fired at 500°C for 5 h. A critical state (CS) concept was used to interpret the results in order to describe the behaviour of the studied soil. Defining the CS is not always straightforward. Several tests showed changing in deviator stress q and volumetric strain ε_v up to the end of tests. Hence, defining the CS requires careful assessments on q–ε_a, Δu–ε_a, q–p′ and v–ln p′ spaces which were performed. A ‘discontinuity’ approach was applied to position the CS on dilatant path in v–ln p′ spaces after considering stress-strain and volumetric strain curves. The critical state line in a v–ln pʹ space from bonded samples exhibited differences to the destructured samples. This suggests that the influence of cementation bond is substantially clear at lower stresses but as stresses increase beyond the stress yield, cementation degradation becomes more significant. The effect of bonding can be clearly visualised from the normalisation of the stress paths of destructured and bonded samples.

KEYWORDS:

• Critical state
• bonded soil
• stress path
• normalisation

Acknowledgements

I would like to thank to Public Service Department of Malaysia and National University of Malaysia (UKM) for granting the author while studying at Durham University, England. This work also supported by Durham University in terms of providing facilities regarding to sample preparations and testing facilities.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

I would like to thank to Public Service Department of Malaysia and National University of Malaysia (UKM) for granting the author while studying at Durham University, England.