Risk of Land Subsidence Related to Underground Karst Caves and Solutions, North-South Vietnam Expressway

Abstract

This paper assesses the risk of land subsidence related to the underground Karst caves at the section Km55+660- Km55+690 of North-South Vietnam Expressway by finite element method using PLAXIS 2D V.8.5 software. The research results show that there is a risk of collapsing the ceiling of the underground Karst caves due to the impact of the embankment process and the vehicle load. The research results also show that the vertical displacement is larger than the allowable residual settlement according to Vietnamese standard; it is necessary to take the soft soil improvement to achieve the allowable residual settlement. Several construction solutions are proposed to prevent the risk of land subsidence in the research section. In particular, flyover through the section with underground Karst caves is the most suitable solution.