This paper presents a study of the influence of the geotextile encasement on the behaviour of soft soils improved with fully penetrating encased columns. This influence is analysed by means of measuring soil column stress distribution, pore pressures and soil deformation during the consolidation process. For this purpose, a horizontal slice of a representative "unit cell" has been analysed by means of small-scale laboratory tests. The tests were carried out in a large instrumented Rowe-Barden oedometric cell. Results showed that the vertical stress supported by encased columns is about 1.7 times that sustained by the non-encased ones. The stress concentration factor for encased columns is between 11 and 25, which is clearly higher than that obtained in tests with non-encased columns, which are between 3 and 6. Finally, the improvement in relation to settlements is presented by the ratio of settlement in soils reinforced with ordinary or encased columns and the settlement of non-treated soft soil. This settlement reduction factor is around 0.6 when the soil is treated with encased columns and 0.8 for soil with non encased columns. (C) 2016 Elsevier Ltd. All rights reserved.