The Effectiveness of Deep Soil Mixing on Enhanced Bearing Capacity and Reduction of Settlement on Loose Sandy Soils

A large portion of Iran railway routes are located in sandy desert areas. Therefore, paying attention to soil stabilization methods seems essential. In present study, in parallel to introducing the deep soil mixing as an efficient and economic method of soil improvement, in the frame work of a practical example, assuming loose sandy soil parameters, feasibility of the method application is investigated. For this purpose, by conducting the plate loading test (PLT) and direct shear test (DST) on the railway embankment and sandy subgrade materials, their shear strength as well as deformability parameters ware achieved. Further, by developing a two dimensional FE model using Plaxis code, the railway embankment stability on loose sandy subgrade is evaluated by using the C-Φ reduction method. The analysis is conducted for two separate cases of subgrade with and without soil-cement columns. The numerical results for embankment with 1.5 m height shows that for the loose sandy subgrade the embankment failure load limits to 447 kN corresponding to a safety factor of 1 while by using the soil-cement columns with diameter of 0.9 m to 1.2 m the failure load varies from 741 to 1274 KN and the safety factor varies from 1.26 To 1.66. Moreover, the total embankment settlement deceased up to 25% in the best arrangement of the columns.