Reinforcement of gypseous soil by stone columns

Abstract

Introduction. Gypseous soil is one of the problematic soils that have substantial strength while dry but lose strength especially in wetting or saturation condition due to the significant reduction of its strength parameter and bearing capacity upon loading where gypseous cementing bonds have been dissolute and collapsed in the wet condition (Soil collapse occurs when increasing moisture weakens chemical or physical connections between soil particles), and therefore resulting in excessive settlements affects the stability of the engineering structures. Gypseous soils occupy about 1.865 million km2 in the world; the percent of gypseous in Iraq is 6.7 % of the total world gypsiferous area and about 28.6 % of the total area of this country.

Materials and methods. Stone column is a soil improvement technique used for stabilization and reinforcing of soft soil (low strength soil) by increasing of bearing capacity (increasing strength) and reducing the settlement and control it (consolidation acceleration).

Results. The aim of this study is to investigate the performance of gypsum soil reinforced by stone columns, where laboratory loading tests were performed on unreinforced and reinforced gypsum soil using big steel box as modeling and stone columns was have different diameters (5, 10, 15 and 20 cm) and fixed depth (30 cm).

Conclusions. The results showed that the settlement decrease with increase the stone column diameter and the bearing capacity increase when diameter increase.