Study on Application of Sea Sand-Cement Column in Soft Soil Improvement for Hai Phong-Nam Dinh Coastal Highway

Abstract

The ground structure of the coastal road of Hai Phong-Nam Dinh alignment consists of 10 to 20-m-thickness soft soil layers, lying near the surface, so the deep treatment methods, such as sand column, sand well, prefabricated vertical drain (PVD), soil-cement, etc. will be a reasonable choice. However, each method has pros and cons. In Vietnam, the river sand resource is increasingly scarce and sand exploitation is causing serious environmental problems. It is necessary to study another material to replace the river sand. The paper proposes the soft soil improvement method by sea sand-cement columns. The laboratory experiment tests allow defining the sea sand and soft soil properties, and the sea sand-cement mixture properties. The experimental results show that the influence of cement content on the strength of sea sand-cement samples corresponding to the curing time. Additionally, the unreinforced soil and single and four-column reinforced soil physical models in 1:10 small-scale have been set up to investigate the effectiveness of sea sand-cement columns in soft soil improvement. The physical model results indicate that the presence of sand-cement columns in the ground decreases significantly the soft soil and embankment settlements.