Evaluation of geosynthetic encased columns in Zambian heterogenous soils

Abstract

The development of Zambia has brought increased large-scale infrastructure construction that has necessitated the need for improved foundation techniques that are both economical and adequate in capacity. Clay and soft soils with low bearing capacities and high compressibility could render structural foundations to perform poorly and shorten the design life of the bridges and structures. This study used a bridge case study in Northern Province, Zambia to investigate the use of geosynthetic encased columns (GECs) to support the bridge embankments to reduce differential settlements. End bearing fully encased columns were compared to floating columns of varying lengths by numerical modelling in PLAXIS 3D. The Hardening Soil and Mohr–Coulomb soil models were used for the column surrounding soil and the GECs in the finite element analysis. The results showed that the end bearing columns had the least differential settlements at the soil surface, whilst the reduction in floating column length increased the punching settlements. Moreover, the shear stress along the interface of the GECs and surrounding soil varied from 20 kN/m² to 142 kN/m², where the end bearing GEC had the least shear stress.