On the role of grain shape in static liquefaction of sand–fines mixtures

Abstract

This technical note presents new experimental evidence for the role of grain shape in the static liquefaction behaviour of sand–fines mixtures. The laboratory experiments comprise a series of strain-controlled triaxial tests on several types of sand–fines mixtures that are intended to clarify a concern remaining in a previous study by the same authors: whether the observed effect of grain shape was due to the differences in hardness of the added fines. The comparison of new test results with the previous ones confirms that it is grain shape rather than grain hardness that is responsible for the observed differences in overall behaviour. Adding fines of rounded shape into a clean sand indeed results in a marked increase of liquefaction potential compared with adding fines of more angular shape into the same sand. It is also shown that the concept of the combined roundness is effective and useful for quantifying in an integrated manner the influence of grain shape and fines content on the overall friction angle of sand–fines mixtures at critical state.