C_α/C_c concept and K₀ during secondary compression

The C_α/C_c concept, which completely defines secondary compression behavior of any one soil in terms of a constant C_α/C_c and the EOP e-log is a powerful practical tool for settlement analysis and interpretation of data from load-controlled and deformation-controlled consolidation tests. The correct procedure for evaluating C_α/C_c for any soil is described. The C_α/C_c concept was used to obtain an expression for the behavior of the coefficient of earth pressure at rest, K₀, during secondary compression. This approach predicts an increase in K₀ during secondary compression. This approach also predicts that the K₀ = 1 condition will not be reached during the typical geologic age of soft clay deposits. Laboratory measurements on the behavior of K₀, including during secondary compression, are presented for four soft clays. The proposed approach also provides an estimate of in situ K₀ in soft clay deposits. Two alternative laboratory procedures were used to determine in situ K₀ for four soft clays. These values compare well with the predictions.