Three Dimensional Effect of Grouted Discontinuous Berms for Passive Support of Diaphragm Walls

Unfavorable lands consisting of problematic subsurface conditions stands as a major challenge against the use of earth berms in the passive side of embedded retaining wall for stabilization and performance improvement. Additional challenges are encountered when discontinuous berms are needed. This paper discusses the use of jet-grout columns in enhancing the ability of discontinuous berms to control the inward movement of diaphragm walls embedded in soft soils during the critical stage of berm removal. 3D finite element analyses were used to model the wall, berm, and grout-column configurations. The effect of the jet-grout column configuration was varied in a parametric study by changing the depth and width of improved area, area improvement ratio of the jet-grout columns, and the opening width of the discontinuous berm. The effect of improvement configuration was depicted in terms of deflections, settlements and bending moments. Utilizing jet-grout columns allowed for the ability of introducing bigger openings through the berm’s removal process, and enhancing performance by decreasing maximum wall deflections, settlements behind the wall and maximum bending moments.