CASE STUDY PROBLEMS ON DISPERSION POTENTIAL FOR YANGONMANDALAY EXPRESS WAY EMBANKMENTS

Dispersive soils which occur in central region of Myanmar are easily erodible and serious problem of stability of embankments, earth dams, earths and earth retaining structures. These soils are found in regions where the annual rainfall is less than 800 mm. Dispersive soil is structurally unstable and the presence of dispersive soil is indicated by occurrence of erosion gullies, sink holes, spew holes and piping. In some parts of the central Myanmar, dispersive soils have to be used for construction purpose since no other soil material is available. Dispersion only occurs in non-saline or rain water. If dispersive soils have been used in the construction of earth-dams and embankments, serious piping and failures are occurred. In Myanmar, some problems are found in Yangon-Mandalay Express Ways (Nay Pyi Taw- Mandalay portion) embankment. The embankment soil is investigated by emersion test in field and then physical tests are done in Yangon Technological University and chemical tests are done in Irrigation and Management of Water Utilization Department in Myanmar. For these tests results, most of the embankment soils are dispersive. This paper presents the soil structural problems along Yangon-Mandalay Express Way and dispersive potential rating for the studied soil