A theoretical retention model for unsaturated uniform and graded soils Jacques Monnet, Dino Mahmutovic, Luc Boutonnier, Saïd Taïbi and Ngoc Lan Hoang E3S Web Conf., 9 (2016) 11007 Published online: 12 September 2016 DOI: 10.1051/e3sconf/20160911007