Abstract: Firstly, an indoor model test was modeled by using the large-scale all-purpose finite element software, ABAQUS and 3D finite element method to verify the reliability of the stability analysis of cave structures. Then, based on the karst geological data of the contract section A11 in Yongan-Wuping highway, the karst caves were approximately regarded as the ellipsoids and the 3D finite element models were established to analyze how the stability of the embankment and the karst cave roof is influenced by roof thicknesses, filled heights, karst cave locations and filling conditions of karst caves. Also, the 2D plain strain finite element method was adopted to make a comparison with the prevailing method for safe thicknesses of karst cave roofs. Research shows that，for cave roof strata which are relatively intact, the safe thicknesses of cave roofs obtained by using 4 as the stability factor of safety of roof tensile failure are too conservative. The safe thicknesses of cave roofs obtained by the beam-slab theory of bending tensile failure are inclined to be conservative too. This is because the actual roof strata do not coincide completely with simplified hypothesises of the beam-slab theory. However, based on the beam-slab theory of bending tensile failure, the safe thicknesses calculated by the maximum bending moments obtained from the finite element analysis are the most economical. For actual karst caves which have obvious 3D effects，the prevailing simplified theory and 2D numerical analysis method are relatively coarse and the 3D numerical analysis method should be adopted. Through analyzing the above problems, the research work offers guidance to the embankments design and karst cave treatment of the highway in the karst regions. Good socioeconomic benefits are obtained. It can be used as a reference for similar engineering application.

Key words: karst region, embankment, roof thickness, filled height, location of karst cave