Creep Characteristics of Organic Soft Clay Soil Using Large–Scale Model

The long-term settlements in organic clay can create a kind of an engineering challenge that appear in most facilities design and construction in areas with deep deposits of soft clay. Peat ground is widely distributed throughout the southern part of Iraq. Peat contains a large amount of organic matter and has a very high natural water content. Three soil samples were collected from depths of 1.5 m, 2.5 m, and 3.5 m, below the soil surface in Halfaya oilfield, which lies east of Missan governorate southern Iraq. A series of tests were conducted in a large-scale model using a plate footing and considering three different percent of organic content. The percent of secondary settlement found is dependent on the stress level applied. A large fraction of the total settlement may be due to secondary compression. The assumption of a constant coefficient of secondary compression, Cα, may not be valid for a long-term settlement of peats. Laboratory data indicate that Cα generally increases with time. Thus, settlement predictions using constant Cα may underestimate field settlement.