关键词: 膨胀土, 路堤填方, 破坏模式, 抗剪强度

Abstract: The embankment diseases of Nanbai Highway （from Nanning to Baise） are serious, and the slide and collapse occurred in embankment of expansive soil inclined ground are most serious. The embankment will slide when it has certain degree of slope between the highway route and its vertical direction. Through investigating collapses of embankment in K169 ＋ 500m - K189 ＋ 400m on the Nanbai road, three failure modes of expansive soil embankment are generalized by the method of FEM, that is, the slide in the cross direction, the slide in the longitudinal direction and the longitudinal-cross slide mode. The failure modes of embankment are simulated by the strength reduction finite element method and the causes of embankment failure are discussed. New thoughts about rule of the ＂Specifications for Design of Highway Subgrades＂ （ JTG D 30--2004） are put forward, which provides a new way of thinking to the research on the subgrade filling of expansive soil.

Key words: expansive soil , embankment , failure mode , shear strength ;