A laminar boundary layer is a layer

Rigid structures: Rigid structures have a rigid and stiff body. It moves all the same. Types: -Gravity: *Avoid sliding overturning *In situ concrete wall *Masonry wall (water between the bricks) *Rockfill -Cantilever: *We save concrete *We need steel reinforcement *Precast concrete wall Green retaining wall -Counterfort: *The counterfort helps to support the vending moments. *Reinforced earth with geosynthetics / We can add a piece at the bottom to avoid overturning. //Drainage of rigid structures: It is done by two methods: Weep Holes: *Holes in the wall that let the water pass through *Drainage Layer and a pipe: to absorb the water (Geosynthetics) Flexible structures: They are built before excavation and are embedded in the ground (embedded walls). His weight is not important. They have important vending moments. They allow the excavation below the GWL. Usually propped (strut, anchor, dead-man…) types: Sheet pile wall *They are usually steel piles, and occasionally precast concrete panels. The panels are very deep and its small thickness. *They have a wavy shape to increase their flexural strength and rigidity. (the inertia moment increase) *They are driven into the soil by vibration hummer, or if the soil is soft by a hydraulic crane. Very useful for a temporary works, we can take the sheet pile out of the soil and use it again. - Construction process: 1 Position of the sheet pile (guide wall) 2 Installation of the first sheet pile 3 Second sheet pile 4 Repetition of process 5 Extension of sheet pile. Diaphragm wall: Usually cast in place concrete (Hincado in situ). The disadvantage is that we must use vibration to drive the wall into the soil, so it could damage nearby structure. Applications: *Permanent Works *In urban areas *Retaining Wall *Deep basements / Parking lots *Deep large diameter shafts (tunnels). Construction method: 1 Guide wall consturction: to define where the panels are going to be. 2 Panel excavation: we excavate non sucessive panels. 3 Installing stop ends. 4 Panel concreting