Investigation of earthquake damage and seismic slope displacements in open irrigation channels using the coupled Eulerian–Lagrangian method

Finite element method (FEM) based slope displacement analysis is used to study stress, strain and displacement to determine the critical slip surface. However, in classical Lagrangian FEM models, mesh distortion may lead to numerical simulations that are difficult to converge and unreliable slope displacements. In this study, two different models, namely the Coupled Eulerian–Lagrangian (CEL) approach and the Lagrangian FEM approach, are used. Seismic responses of the main channel dam under empty and full conditions are analysed. The CEL model of the fluid in the channel can represent the water surface sloshing and displacement fairly realistically. During the 2023 Kahramanmaraş earthquake, the amplitude of water sloshing in the channel reached approximately 20 and 95% of the water level for the Lagrangian and CEL models, respectively. Considering the fluid–structure interaction, the ground displacements in the filled model decreased by 25–89% compared with the empty model. The pre- and post-earthquake equivalent plastic stress values increased by 180% for the empty case and 328% for the full case in the CEL model compared with the Lagrangian model. The findings emphasize that the combined effects of soil and fluid dynamics should be taken into account, especially in analyses involving complex geometries and seismic activity.