Numerical Analysis of a 3D Unit Cell Model for Soft Soil Reinforced with Different Granular Columns

Recycled aggregates have been increasingly considered in recent years, owing to the limited supply of natural aggregates coupled with the corresponding carbon footprint. Recycled aggregates are aggregates prepared from construction and demolition waste. Their use aims to reduce energy consumption and contributes to reducing waste harmful to the environment. This study is based on a number of numerical tests using the finite element method of PLAXIS 3D software with the elastic-perfectly plastic behavior model and the Mohr flow criterion for all materials. A unit cell model of soft soil treated with three types of granular columns was loaded to failure: ordinary stone columns (OSCs), sand-fiber mix (SFM) and recycled aggregate porous concrete pile (RAPP). An extensive parametric study was conducted to investigate the effect of column type, friction angle, elasticity modulus, column length and geotextile effective stiffness on the behavior of soft soils. The results of numerical tests indicated that the bearing capacity of the recycled aggregate columns is three times greater than that of columns of natural aggregates. The findings of this research are given in the form of load-settlement graphs, which made it possible to release recommendations to carry out works using this technique. KEYWORDS: Soft soil, Granular column, Numerical analysis, Unit cell, Bearing capacity, PLAXIS 3D software