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This paper investigates shear banding as a possible failure mode for silt–clay transition soils under general three-dimensional stress conditions. Drained and undrained true triaxial tests with constant b values were performed on tall prismatic specimens of such soils with systematically varying silt contents. Based on the values of critical plastic hardening modulus, shear banding does not govern the strength characteristics of the soils for b values less than 0.2. For larger b values, shear band formation is essentially critical as it takes place in the hardening regime of the stress–strain curves prior to the smooth peak failure points. An increase in silt content appears to move the onset of shear banding to lower levels of shear in the stress–strain relations of the silt–clay transition soils. It is also demonstrated that a non-associated constitutive model with a single hardening law is capable of accurately predicting the onset of shear banding in normally consolidated silt–clay transition soils based on bifurcation theory.

This paper investigates shear banding as a possible failure mode for silt–clay transition soils under general three-dimensional stress conditions. Drained and undrained true triaxial tests with constant b values were performed on tall prismatic specimens of such soils with systematically varying silt contents. Based on the values of critical plastic hardening modulus, shear banding does not govern the strength characteristics of the soils for b values less than 0.2. For larger b values, shear band formation is essentially critical as it takes place in the hardening regime of the stress–strain curves prior to the smooth peak failure points. An increase in silt content appears to move the onset of shear banding to lower levels of shear in the stress–strain relations of the silt–clay transition soils. It is also demonstrated that a non-associated constitutive model with a single hardening law is capable of accurately predicting the onset of shear banding in normally consolidated silt–clay transition soils based on bifurcation theory. [ABSTRACT FROM AUTHOR]

The influence of silt content on the stress-strain, pore pressure change and strength characteristics of silt-clay transition soils is presented. One-dimensional consolidation tests and consolidated-undrained triaxial compression tests on three soils of similar base clay but with different silt contents were performed. The undrained triaxial tests were carried out on specimens of the siltclay soils with different overconsolidation ratios. It was observed that the tested silt-clay soils were less compressible when consolidated in the vertical direction as the silt content increased. During triaxial shear, the silt-clay soils exhibited stiffer stressstrain response with increasing silt content. The pore pressure changes increased with the amount of non-plastic silt in the soils, particularly at low overconsolidation ratio (OCR). The undrained shear strengths and effective friction angles significantly increased with the amount of silt. It was observed that the degree of overconsolidation significantly influenced the undrained shear strengths of the silt-clay soils but less so for the effective friction angles. [ABSTRACT FROM AUTHOR]