DEM simulations of soil-pile interface under static and cyclic loading

In this study, Discrete Element Method (DEM) was used to simulate interface direct shear tests for both constant normal load (CNL) and constant normal stiffness (CNS) conditions. The model was calibrated and validated using laboratory data. Simulations were made for both static and cyclic tests for different amplitudes at normal stress levels ranging from 100kPa to 400kPa on sand having relative density of 50%. No major difference was observed between static CNS and CNL tests for shear stress behaviour. However, a decrease in normal stress was observed in CNS tests which were evident from the imposed boundary conditions. In cyclic CNS tests, degradation of shear stress was observed for higher displacement amplitudes. Shear band thickness was measured from rotation diagrams and was observed to be 5 to 10 times D50 for all the tests