Behaviour of Encased Stone Columns in Soft Clay

Abstract

Ground improvement techniques are commonly used at many sites where the existing soil conditions are very weak which to lead to unsatisfactory performance. encased stone columns technique is employed to enhance the bearing capacity, strength, and stiffness of soil to reduce settlement, and accelerate the consolidation rate of the surrounding soft soil.In this research, a series of (62) cases have been made to investigate the behaviour of single encased stone columns in soft clay soil to figure out the encasement effect and its properties compared to that without encasement over the single stone column in soft clay soil using finite element model (FEM) using PLAXIS 3D program on column with two diameters (D=0.4m and D=0.6m) where the length of the column to diameter is kept at (L/D=10) in all cases. Stone columns are studied either it is without encasement which is an ordinary stone column (OSC) or with encasement as it is encased stone column (ESC) column is surrounded by geotextile with different stiffness. This paper introduces the numerical analysis, and the results where there is an increasing in the bearing capacity of the stone column in the encased columns than the ordinary stone columns. At an internal friction angle of =45°, the BCR rise in ESC for a column with diameter D= 0.40 m reaches maximum value of 227 %, While at the same internal friction angle =45°, the BCR rise in ESC for a column with diameter D= 0.60 m reaches maximum value of 200 %.

Keywords

• encased
• stone column
• plaxis 3d
• soft clay soil
• geotextile