Extended hypoplastic model incorporating the coordination number for the simulation of granular flow

In this contribution, a hypoplastic viscous soil model incorporating viscous and grain‐inertia rate effects observed in granular flows is enhanced by means of the coordination number, which allows to characterize the evolution of the microstructure of the granular material. Near a critical solid volume fraction and critical coordination number there exists a transition from a solid‐like (rate‐independent) to a flow‐like (rate‐dependent) behavior of granular materials. This information is used to calibrate a so‐linear concentration factor, which controls viscous and grain‐inertial rate effects in terms of the rate dependent evolution of the coordination number. The influence of this proposed hypoplastic model considering the coordination number is investigated in this paper by means of a simple undrained shear test .