Improvement of soft soils using reinforced sand over stone columns

In the present study, a series of laboratory model tests have been developed to study the behavior of unreinforced and geogrid-reinforced sand bed resting on stone columns. It has been observed that the soft clay is improved with stone columns. The diameter of stone columns has been taken as 50 mm, three stone columns have been used in the study with spacing of 75mm, while the footing is represented by a plate of 350x250x10mm for all the model tests carried out. Load was applied to the soil bed through the footing until the total settlement reached at least 5% of footing length. The influence of the thickness of unreinforced as well as geogrid-reinforced sand bed and the number of geogrid reinforcement on the performance of stone columns have also been investigated. The inclusion of geogrid layer within sand bed also increases the load carrying capacity and decreases the settlement of the soil. However multilayer reinforcement system is effective to transfer the stress from soil to stone columns. Significant improvement in load-carrying capacity of soft soil is observed due to the placement of sand bed over stone columns. Single layer reinforcement with stone columns is very effective to reduce the total settlement as there is considerable reduction in the total settlement due to stone column itself. The inclusion of reinforcement in the sand bed decreases significantly the depth of sand layer. [Nagy Abdel Hamid El Mahallawy. Improvement of soft soils using reinforced sand over stone columns. Life Sci J 2012;9(2):269-276]. (ISSN:1097-8135). http://www.lifesciencesite.com.43.