abdoihosein haddad - dept.of civil engineering, semnan university, semnan, iran
saeed khodaian - earth science faculty, shahid beheshti university. Tehran

in this paper a crireria to predict collapse potential of semnan soils is presented,based on double oedometer tests. The concepa of "collapse pressure" and the coefficient of collapsibility C, are soils saturated with various types of liquids disclose variable collapse behavior, depending on whether saturation is caused by drinking water, sewage, or acidic water. Analysis of soil-liquid chemical interaction suggests that collapse of soil tested is due to dispersion of the intergranular clay cementing fraction