Small-strain shear modulus and yielding characteristics of compacted high-plasticity clay

This experimental study describes the elastic and yielding response of compacted high-plasticity clay in conjunction with deformation characteristics at relatively larger strains for different stress paths and stress states. K-0 consolidated undrained triaxial compression and extension stress path tests were conducted on compacted Nagpur cohesive soil with bender element measurements to explore the elastic and yielding response of soil. The experimental results showed that the stress path direction had a significant impact on the stress-strain-strength properties of soil as the peak deviatoric stress was found to increase with the increase in stress path angle. The measured small-strain shear modulus (G(max)) values were observed to be a function of the mean effective stress (p ') with slight dependency on deviatoric stress (q). G(max) was found to reduce with increase in strain level during shearing. An attempt was made to formulate an empirical correlation for compacted cohesive soil based on the elastic shear stiffness in pre-yield conditions. This correlation was further used to determine the yielding criteria of compacted cohesive soil along with the other two well-established criteria of stress-strain and strain energy.

Automated summary

This experimental study investigates the elastic and yielding response of compacted high-plasticity clay and its deformation characteristics at larger strains for different stress paths and stress states. The study finds that the stress path direction has a significant impact on the stress-strain-strength properties of the soil, with the peak deviatoric stress increasing with the increase in stress path angle. The small-strain shear modulus is observed to decrease with increasing strain level during shearing. The study also attempts to establish the yielding criteria for compacted cohesive soil based on the elastic shear stiffness in pre-yield conditions.