Abstract: Expansive soils have brought great harm to engineering projects due to the properties of water swelling and dehydration shrinkage. In this article, expansion and contraction tests were carried out on expansive soils mixed with varing cement content. Results suggest that the optimum cement dosage was 6%. The modified expansive soil was then used as reinforcement material to replace the surface layer of cannel slope in the middle route of South-to-North Water Transfer Project. The protection effect was field monitored by inclinometer pipe and deformation tube. Results prove that cement-treated expansive soil as a backfill could solve the shallow instability problem of expansive soil slope.

Key words: cement-modified expansive soil, middle route of South-to-North Water Transfer Project, cannel slope, swelling shrinkage test, slope protection effect