Performance of a Geobag Revetment. II: Numerical Modeling

An intensive study including laboratory experiments and use of a computer software on geobag revetment performance was reported in the companion paper. To represent the failure initiation, a set of quasi-physical model runs was carried out and the conveyance estimation system (CES) computer software was employed to predict active shear stress on geobags and mobile sand bed formation. The CES could predict the depth-averaged velocities in the laboratory measurements with reasonable accuracy. This paper reports the second part of the study, dealing with the discrete element modeling (DEM) simulation. The CES results were used for preparing a mapped velocity field for a coupled DEM simulation of geobag revetment failure. The validated DEM model could identify well the critical bag location in varying water depths and with varying bed formations. Toe scour, one of the major instability factors in revetments, and its influence on bottommost layer of the bags were also reasonably represented in this DEM model. It is envisaged that the use of a DEM model will provide more details on geobag revetment performance in riverbanks.