Modified Isotropic Compression Relationship for Cement-Admixed Marine Clay at Low Confining Stress

What is it about?

A modified log-linear compression relationship for the pre-yield isotropic compression behavior of cement-admixed marine clay is proposed. The difference between this modified relationship and the conventional log-linear relationship is the use of the tensile strength as an added stress to the mean effective stress. This allows the cement-admixed clay to retain a finite specific volume as the mean effective stress approaches zero, which is more consistent with the fact that cement-admixed clays remain intact even under zero effective stress condition. Comparison with data from isotropic compression test shows that the addition of the tensile strength to the mean effective stress leads to a remarkable improvement in linearity, indicating a much improved fit to the log-linear relationship. The resulting pre-yield compression index implies a non-zero equivalent effective bulk modulus, which is also intuitively more reasonable. At effective stress levels much lower than the tensile strength, the bulk modulus is approximately constant; this is also consistent with the notion of linear elastic behaviour at low stress level.

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Why is it important?

The modified compression relationship removes some of the inconsistencies between the classical e-log p' relationship and experimental observations.