Thick slurry wall excavation rigs

Thick slurry cut-off walls are diaphragm-type walls made of bentonite-cement. The trench is usually dug by grab, the permanent cement mix can be used as drilling mud to support the trench during excavation.

When a Hydrofraise rig is used, the bentonite-cement mix must displace the drilling mud as each panel is completed. The joints between panels are formed by having the second trench bite overlapping the primary panel.