Domain heterogeneities in geomaterial modeling: Integrating multi-scale FEMxDEM and second-gradient approachesTrung-Kien Nguyen, Thanh-Trung Vo, Anh-Tuan Vu and Gaël CombeEPJ Web Conf., 340 (2025) 09005DOI: https://doi.org/10.1051/epjconf/202534009005