Full-Scale Field Studies to Evaluate Deep Soil Mixing in Stabilizing Expansive Soils

Abstract

An evaluation of deep soil mixing (DSM) technology in stabilizing expansive soils was conducted by designing and constructing two full-scale test sections. The test sections were instrumented and installed with different numbers of DSM columns and area ratios. Their performance was evaluated by comparing the test sections with two untreated test sections. The performance of the DSM test sections was measured by addressing the shrink and swell behaviors using vertical and lateral soil movements and the swell pressures within the treated soil mass. This paper discusses the construction of the test sections, the instrumentation details, and comprehensive analyses of the field monitored data. The untreated test sections experienced absolute vertical soil movements on the order of 35 mm or greater, whereas the treated test sections had movements in the range of 10 to 25 mm. Similar observations were recorded for the lateral soil movements and swell pressure changes in both the untreated and treated sections. Unlike the DSM-treated test sections, the untreated test sections showed repeated soil movements with field moisture content changes due to periodic dry/wet climatic conditions. Results from nondestructive testing (NDT) revealed that the overall stiffness of the DSM-treated test sections was superior to that of the untreated sections. This study showed that DSM technology is a viable option for stabilizing expansive soil formations with moderate to deeper active depths.