Dry Deep Soil Mixing Soil-Cement column panels as bottom struts for excavation support: Revising of design methodology in Scandinavia

Deep Soil Mixing is an often-applied technique in the reinforcement of embankments, but little has been done to investigate and understand its behavior when used in excavation projects. The present research presents a database of the results of previous studies on the Deep Soil Mixing technique in Scandinavian soils. An expression that can estimate the improved soil strength when a specific binder content and binder ratio is mixed with the soil is proposed and its pertinence is tested with two full-scale tests. The proposed mathematical expression to predict the improved strength yields a good representation of the available data. The full-scale tests, in which a braced steel sheet pile wall interacts with panels of DSM overlapping columns are used for back-calculating the improved soil strength and stiffness properties. It is observed that the weighted average procedure for calculating properties should be used with care and that the loading conditions affect the strength and stiffness that the improved soil can develop. The drained analysis with a fixed friction angle and a cohesion intercept estimated from the undrained shear strength is the suggested design procedure to assess deep excavations involving improved materials