Assessment of Compression Index of Busan and Incheon Clays with Sedimentation State

Abstract

A series of 1-D consolidation tests are performed on the undisturbed and remolded specimens for Busan and Incheon clays in order to propose empirical correlations predicting the compression index of natural clays. For both clays, the compression index is found to correlate best with w_n and to have the weakest correlation with I_L among the four soil properties (w_L, I_p, w_n, I_L). It is observed that, for Incheon clay, the multi-variable equation (w_L and w_n) moderately improves the accuracy of the empirical correlation, while, for Busan clay, it provides negligible improvement compared with the equations with a single soil property. In this study, the sedimentation state of natural clay is defined as the difference in the void ratio between the natural and remolded clays at yield stress (Δe_r,), and the prediction equations that can consider the sedimentation state are suggested. It is noted that, for Busan clay, the equations considering the sedimentation state provide a significantly better accuracy than the equations with multiple soil properties, whereas, for Incheon clay, both types of equations provide a similar accuracy.

Keywords:

• Compression index
• consolidation test
• remolded clay
• sedimentation state

Notes

Note: w_L: Liquid limit, I_p: Plastic index, w_n: Natural water content, I_L: Liquidity index, I_S: Shrinkage index, n_o: In-situ porosity, e_o: In-situ void ratio, e_L: Void ratio at the liquid limit.

Note: All regression equations in the table are suggested in this study.

w_L: Liquid limit, I_p: Plastic index, w_n: Natural water content, I_L: Liquidity index, σ′_vo: In-situ vertical effective stress.