Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Stone column

The Effect of Granular Material on Behaviour of Stone Columns in Soft Clay under Embankment

Shaker Mahmood Mohammed

Engineering and Technology Journal, 2015, Volume 33, Issue 9, Pages 2212-2219

The stone column material is one of the main controlling parameters in the design of stone columns. It is shown to be affecting the stiffness of the stone columns and hence settlement of the treated soil. Severalmaterials with friction angles of stone column material used to reinforce weak soil as stone columns. Finite element analyses were carried out to evaluate the settlement of soft clay reinforced with stone columns using 15-noded triangular elements in Plaxis 2D v8 software. An analysis carried out using Mohr-Coulomb’s criterion model for stones columns and soft soil clay. The numerical results from the FEM provide calculated settlement, excess pore water pressure and lateral bulging of the stone column. It was found that friction angle 40o reduces the total settlement and lateral bulging to approximately 0.038m, 0.00086mrespectively of that of reinforced clay with friction angle of crushed stone 27.5o.

Soft Clay Soil Improvement Using Stone Columns and Dynamic Compaction Techniques

Hussein H. Karim; Mohammad M. Mahmood; Raida G. Renka

Engineering and Technology Journal, 2009, Volume 27, Issue 14, Pages 2546-2565

Soft clays are widely spread in Iraq particularly in its southern Mesopotamian plain. As many sites within these regions may be used for vital projects; an adequate solution has been found out to improve such clays using stone column and dynamic compaction methods. For this purpose, the present paper has presented the laboratory measurements of the properties of such clays and their settlements at different applied stresses. Thirteen soil model tests have been made, at 27% water content and 9 kPa undrained shear strength, to examine their
behaviors under loading .The tested models include : (1) model for untreated soil ; (3) models for soil treated with stone columns (1,2 and 3 columns) with 30mm in diameter and 180mm length ; (9) models for soil treated with dynamic compaction using drop weights 2 , 3 and 5kg at three different drop heights ( 500 , 750 , and 1000mm ) . For dynamic compaction, the behavior of soil stress - settlement
reflects two stages for 2 and 3 kg drop weights with slow and rapid settlements respectively. Whereas , three stages were identified using 5kg drop weight with slow, medium and quick settlements. No considerable effect of drop height and no noticeable improvements have been indicated with soil model treated by dynamic compaction except for weight drop of 5kg but with less improvement ratio compared with stone columns model test. Whereas, the behavior of stresssettlement
using stone columns reflects three stages with slow, rapid and slow
(again) settlements . In comparison with untreated soil, the maximum cumulative settlement improvement ratios were 69% and 178% at applied stress of 30 kN/m2 for soil models treated with dynamic compaction ( 5kg drop weight ) and 3 stone columns respectively .