DEM-CFD investigation on the effects of angularity and roughness on the mass loss of soil rock mixtures

The migration of soil rock mixture (SRM) in filling is a widespread problem in the research of water and mud inrush. Therefore, the discrete element method coupled with computational fluid dynamics (DEM-CFD) was used to simulate particle migration of SRM materials. In this work, a 3D random mesostructure modelling system of SRM materials was developed and used to generate SRM materials with different angularity. Based on the governing equations of particle migration and fluid flow, numerical simulation is carried out to characterise the variable mass loss of SRM materials with various angularity and roughness. The results demonstrate that the development and production of secondary development of particle loss would be inhibited when the angularity of rock is more than 0.110, and the loss characteristics of SRM materials which has less than 0.110 angularity would tend to be that with non-angular rock. It can be also found that the smaller the rock or soil roughness, the earlier the start time of the secondary particle loss, the longer the duration of secondary particle loss and the greater the loss quality induced by secondary water inrush. The settlement of SRM materials is positively correlated with the particle mass loss. Moreover, the feasibility and rationality of the model are validated by comparing the experimental results with numerical results. This work provides a valuable reference to study the particle migration of SRM materials during water inrush in tunnel engineering.