Deep Soil Mixing in Sabkha Soils for Foundation Support in United Arab Emirates

Abstract

An extensive experimental and numerical investigation was done on one of the first applications of wet deep soil mixing (DSM) in Sabkha soils in the United Arab Emirates (UAE). The aim was to increase the bearing capacity of a shallow foundation and to reduce the foundation settlement. In local geotechnical engineering practice Sabkha soils have been well known as a problematic soil (i.e., having larger fines content, higher sulfate and chloride contents, lower shear strength, and higher compressibility) compared to surficial sandy soils that prevail across the country. A mix of 30% Ordinary Portland Cement (OPC) and 70% of Ground Granulated Blast-furnace Slag (GGBS) was used as cementitious binder. The DSM design involved two steps: (1) soil–cement mix design that determines the design strength of soil–cement mixture; and (2) geotechnical design that determines suitable pattern of DSM columns. A numerical analysis using Plaxis 3D was also conducted to verify the geotechnical design which was done with a simple analytical method. To confirm the hypothesis made during design, especially the strength of soil–cement mix columns with Sabkha material, a trial test that consists of installation of four DSM columns in which fresh cube samples are taken and a real-scale zone load test was performed at the site location. All testing proved that the DSM design was satisfactory. The results confirmed that soil mixing is a proper technology to improve the strength of Sabkha soil in economical way considering also the time saving during execution.