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

As the large portion of Iran railway routes have been located in sandy desert areas so 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 was 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 were achieved. In continue by developing a 2 dimensional FE model using Plaxis code, the railway embankment stability on loose sandy subgrade was evaluated by using the C-Φ reduction method. The mentioned analysis was conducted for two separate cases of subgrade with and without soil-cement columns. The obtained numerical results for embankment with 1.5 m height shows that in the case of loose sandy subgrade the embankment failure load limits to 447 kN corresponding to 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 was deceased up to 25 percentage in the best arrangement of the columns.

Keywords:

Deep Mixing , ground improvement , Plaxis2D modeling , Settlement , Bearing Capacity