Micromechanical model to predict sand Densification by Cyclic Straining

Abstract

It has been observed that the application of cyclic shear loading to a dry sand and other cohesionless soils results in a progressive volume reduction and a relative density increase. Although this densification is larger and takes place faster in loose sands, it occurs in both loose and dense soils, and is caused by the tendency of any sand to contract under a small shear strain. A micromechanical statistical model was developed by the writers to interpret and compute the compaction of such a dry granular soil subjected to a strain‐controlled cyclic simple‐shear test. The method postulates that an important role is played in the compaction phenomenon by the spatial statistical distribution of porosity within the soil specimen. Numerical simulations of densification are presented using the proposed model, which are in excellent agreement with observed sand compaction in actual cyclic simple‐shear tests. These simulations provide new insight into the densification process, and especially on the significance of the evolution of the porosity distribution with the number of strain cycles.