In situ methods and their quality assessments in ground improvement projects

Quality Assessments (QA) of Deep Mixing (DM) based stabilized soils at a given project site are needed prior to any infrastructure construction since deep mixing methods adapted in the field do not replicate the mixing process achieved in laboratory conditions. Hence, strength and stiffness properties of field treated soils are often lower than those of laboratory treated soils. For field QA studies, in situ methods are preferred since in situ methods provide repeatable, reliable, and quick assessments of soil strength and stiffness enhancements. Several in situ methods have been used across the world for QA studies on DM projects. This paper presents a few selected intrusive in situ methods and their applications in quality assurance related investigations on deep mixing treated soil columns. A few of these methods presented here include standard penetration test, cone penetration test, and pressuremeter tests. Effectiveness of these methods in QA studies are explained along with a few case studies reported in the literature. Both advantages and limitations of these in situ methods in their QA studies are described.