Evaluation of the load-bearing capacity of geosynthetic encased columns (GEC) in soft soils

Abstract

Soft soils can be improved with granular columns to increase load-bearing capacity and reduce embankment settlements. However, conventional columns often undergo excessive lateral deformation near the top due to the low confinement provided by very soft soils. Geosynthetic encasement overcomes this limitation by offering lateral confinement. In this context, geotextile-encased columns (GECs) are used beneath embankments on very soft saturated fine soils (Su < 15 kPa). This study evaluates the behavior of GECs in large-scale physical model tests. The experimental program simulated column installation and staged embankment construction. Tests were instrumented to monitor internal soil stresses, settlements, and pore pressures. Four load tests were performed, varying the radial stiffness of the encasement. Performance was assessed in terms of settlements, pore pressure response, and stress redistribution between soil and columns. Results indicate that GECs can sustain stresses 6–10 times higher than the surrounding soil. With increasing encasement stiffness led to pronounced stress concentration in the columns, which carried vertical stresses up to about four times the applied surcharge.