Since several decennia, the deep soil mix (DSM) technique has been used for ground improvement (GI) applications. In recent years, soil mix walls (SMW) have become an economical alternative to traditional excavation support systems. The present paper concentrates on the application of SMW technology in Belgium. It focuses on the three main types of DSM systems currently used in Belgium: the Cutter Soil Mix (CSM), the Tubular Soil Mix (TSM) and the CVR C-mix® techniques. In a second step, BBRI information sheets (BBRI, 2012a and b), developed within the framework of the Flemish regional research project IWT 080736, are presented. BBRI info sheets have been established for the purpose of helping contractors to improve the quality control (QC) of their finished product. They consist of guidelines for the execution phases and give some requirements with regard to the material quality, the characteristic dimensions, the bearing capacity and the lateral SMW displacement. The BBRI info sheets define QA (Quality Assurance)/QC requirements in function of the DSM application - retaining wall, water barrier or foundation - and with regard to the permanent or temporary use of the construction. The acceptance criteria are proposed in terms of the number of unconfined compressive strength (UCS) tests, the limitation of soil inclusion percentage into the mix, the determination of the elastic modulus and the execution tolerances. Finally, the BBRI info sheets are discussed from an international view point regarding QA/QC procedures for deep mixing.
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