Seyed Abolhasan Naeini - Full Professor in Department of Civil Engineering, Imam Khomeini International University,Qazvin, Iran
Elham Ghanbari Alamooti - PH.D Candidate in Department of Civil Engineering, Imam Khomeini International University,Qazvin, Iran,

Construction of embankments on soft soil is an important issue in geotechnical problems due to large soil settlements,losing bearing capacity and large lateral displacemnets. During the last decades, different improvement methods have been developed to overcome these problems. Preloading is a traditional method wherein soft soil is subjected to embankment load for a specific time, before construction of any structure on the soft soil. This leads to excessive pore water pressure and drainage which concludes in large settlement and hence soil strength parameter improves. Recently deep mixing methods are used as soil improvement method, wherein columns of soil are mixed with cement or other stabilizing material to improve soil strength and bearing capacity. Soil-Cement (SC) column and Cement-Fly ash-Gravel (CFG) column are two common methods in deep mixing. In this study, the consolidation behavior of soft soil improved by SC and CFG columns is investigated under embankment load and compared with the behavior of soft soil improved by preloading method. The problem is simulated in a finite element program, Plaxis 2D, in plane strain condition. The results consist of pore water pressure, lateral displacement and settlement with time. Finally the efficency of CFG column method, in increasing embankment stability could be observed from numerical results

Preloading method, Deep mixing method, CFG columns, SC columns, soil improvement method.