Treatment of Iraqi collapsible soil using encased stone columns

Stone columns are widely used globally due to their versatility and relative wide applicability to treat different soil and foundation situations but much of the research undertaken to date has focused on their use in soft soils. In countries like Iraq the use of stone columns is still limited from a practical point of view, chiefly as many other soil conditions are commonly encountered. These include collapsible soils: soils that are prone to relatively rapid volume compressions (through collapse of metastable fabrics) that occur due to the action of load and/or increases in water content. Recent work has opened up the possibility to use stone columns in these soils by the use of encasement, thereby overcoming the impact of loss of lateral support when collapse occurs. Area of potential will be discussed; why stone columns could be beneficial for use in Iraq and how employing them as an alternative to conventional ground improvement techniques in number of Iraqi projects would be cost saving and has other benefits. Also, a review of soil conditions in Iraq will be presented and focusing how to treat collapsible soil by encasing the individual stone column by geofabrics illustrating the scope for developing a reliable design approach which suits Iraqi soils. An evidence of their potential applicability in Iraqi soils will be presented. Moreover, the installation technique, facts regarding failure, factors control the behaviour of encased stone columns, calculation of bearing capacity and settlement and some previous related laboratory work will be reviewed as well as recommendations regarding the proposal work in this field are produced with this paper.