Competition between rate strengthening and gravitational acceleration induces stick-slips of inclined granular flow

This study conducted experiments on dry granular mass released on an inclined flume. The periodic acceleration and deceleration of the flow, that is, the stick-slip phenomenon, was observed during the experiments. To investigate the stick-slip motion mechanism, numerical simulations were conducted with the inclusion of the shear-strengthening μ(I)-rheology into the elasto-plastic models of granular flow. The stick-slip phenomenon was captured naturally without the modification of the empirical friction law. The results revealed that the competition between the rate strengthening implemented by the μ(I)-rheology and the gravitational acceleration along the inclined plane induces stick-slips. By considering the experimental results in combination with the simulation results, the effects of the particle size, gate size opening, surface roughness, and frictional parameters of μ(I)-rheology on the stick-slip phenomenon were elucidated.