The New Engineering Treatment Techniques of Expansive Soils Subgrade for GuangXi Nanning-Youyi Guan Expressway

Treatment of expansive soil subgrades is a worldwide technical problem, which needs to be studied and solved urgently due to the rapid development of large-scale highway construction in China. In order to solve the problem, a research group have carried out a field survey in Ningming area. There the construction of Nanning to Youyi Guan Expressway (NYGE) has undergone serious geological disaster caused by Ningming expansive soil. On the basis of worldwide successful and unsuccessful experiences of treating expansive soil projects, the research group analyzed the causes of landslides and conducted a lot of laboratory and field tests on properties of expansive soil. Aiming at the three typical properties of expansive soil and the characteristics of subgrade failure, the group adopted enveloping techniques, and executed some creative schemes to treat slopes of embankments and cuts. All measures taken by research group were successful and have effectively solved the technical problem in the subgrade construction of NYGE. The research outcomes are also useful for railway construction, hydraulic works, and municipal works.