Performance of Stone columns in multi-layered soils under the action of Seismic loads-PPT Presentation

PPT Presentation

Pdf Summary

This study investigates how stone columns perform in naturally layered soils subjected to seismic loading, an area not well represented by design methods based on homogeneous deposits. Stone columns can improve ground through reinforcement, load transfer, and drainage, potentially reducing settlement and liquefaction risk.<br /><br />The researchers used PLAXIS 2D to model representative unit cells with and without stone columns in dense sand, soft clay, stiff clay, and a multilayered soil profile. The numerical approach was checked against results from a large-scale shaking-table test. Models were then subjected to the 1979 Imperial Valley earthquake record. The columns were 0.8 m in diameter, 27 m long, and arranged on a triangular grid at 1.7 m spacing.<br /><br />Results showed that stone columns reduced excess pore-water pressure more noticeably in soft clay than in dense sand or stiff clay, owing to the shorter drainage path. Without columns, elevated pore pressure and settlement occurred during the strongest shaking, around 8–12 seconds. In the layered site profile, the columns reduced maximum vertical settlement by 53%. They also substantially reduced the maximum cyclic stress ratio in the soft clay, while carrying greater cyclic shear stress than the surrounding clay.<br /><br />Overall, stone columns showed the strongest benefits in soft clay. The findings suggest potential for reducing seismic settlement and pore-pressure buildup in layered ground, but further investigation is needed to confirm their effectiveness under seismic loading.

Keywords

stone columns

seismic loading

layered soils

PLAXIS 2D

pore-water pressure

settlement reduction

liquefaction mitigation

soft clay

shaking-table test

Imperial Valley earthquake