Secondary Compression

A large volume of reliable measurements of one-dimensional settlement, observed in the laboratory and in the field for a wide variety of natural soil deposits, demonstrate that during secondary compression (delta)S/(delta)  log  t may remain constant, decrease, or increase over a significant period of time. This important body of observed data and associated explanations in terms of the C(alpha)/Cc law of compressibility have been apparently overlooked in attempts to describe secondary compression by means of mathematical formulas. Data are presented to illustrate the limitations of "first-order rate equations" to describe secondary settlement.