Deep mixing methods have been becoming in the last decades more and more common techniques in the field of geotechnical engineering and have been applied to many different contexts for a wide range of applications like ground improvement, foundation elements, slope stability, soil liquefaction mitigation, cut-off and/or retaining structures etc. Despite the extensive use of such methods and the general definition of homogenization provided to describe this ground improvement procedure, the concept of homogeneity in deep soil mixing is still not well investigated and, in most of the cases, the achievement of a predefined target value of jobsitespecific quality indexes, e.g. the blade rotation number, is assumed as indication that an homogeneous mass of treated soil has been produced in-situ. In other cases, the required homogenization is confirmed only indirectly by means of strength laboratory tests on wet-grab samples and/or cores. This paper summarizes and discusses the concept of homogenization in deep soil mixing and the findings of previous research studies on this topic. In addition, it provides a new quantitative approach for a direct estimation of the degree of homogeneity achieved within the soil mixed elements allowing for further statistical analyses and an overall better understanding of the amount and type of untreated soil particles within the improved soil matrix.
Subjects: deep mixing, QA/QC, homogenization
Author: Diego Bellato, Ph.D., M.Sc., P.E., Paolo Fania, M.Sc., P.E. and Ulli Wiedenmann, Dipl.-Eng. (FH)
Publisher: DFI, EFFC