General Stress-Strain-Time Function for Soils

The stress-strain-time behavior of soils may assume a variety of form depending on such factors as soil type, soil structure, stress history, drainage conditions, and type of loading. Generalizations concerning creep in soils suggested by various investigators are sometimes contradictory. However, test results show that there exist linear relationships between logarithm of strain rate and logarithm of time for a given stress and between logarithm of strain rate and stress at any given time, provided the creep stress level is between the practical limits of about 30% to 90% of the initial soil strength. These findings lead to a simple three-parameter general stress-strain-rate-time relationship. Integration of this relationship yields creep curves which are observed to agree in form with the experimental results.