There are many different types of excavations performed during the construction of a project. For example, soil may be excavated from the cut or borrow area and then used as fill.
Another example is the excavation of a shear key or buttress that will be used to stabilize a slope or landslide. Other examples of excavations are as follows:
1. Footing Excavations. This type of service involves measuring the dimension of geotechnical elements (such as the depth and width of footings) to make sure that they conform to the requirements of the construction plans. This service is often performed at the same time as the field observation to confirm bearing conditions.
2. Excavation of Piers. As with the excavation of footings, the geotechnical engineer may be required to confirm embedment depths and bearing conditions for piers. Figure 1 presents typical steps in the construction of a drilled pier.
FIGURE 6.44 Typical steps in the construction of a drilled pier: (a) dry augering through self-supporting cohesive soil; (b) augering through water bearing cohesionless soil with aid of slurry; (c) setting the casing.
3. Open Excavations. An open excavation is defined as an excavation that has stable and unsupported side slopes.
4. Braced Excavations. A braced excavation is defined as an excavation where the sides are supported by retaining structures. Figure 6.45 shows common types of retaining systems and braced excavations.
Common types of retaining systems and braced excavations. (From NAVFAC DM-7.2, 1982.)