Engineering and Construction

Because of the public safety considerations that are involved, building codes contain numerous provisions relating to the design and construction of excavations and foundations. The IBC defi nes which soil types are considered satisfactory for bearing the weight of buildings and establishes a set of requirements for subsurface exploration, soil testing, and submission of soil reports to the local building inspector. It goes on to specify the methods of engineering design that may be used for the foundations. It sets forth maximum loadbearing values for soils that may be assumed in the absence of detailed test procedures (Figure 2.5). It establishes minimum dimensions for footings, caissons, piles, and foundation walls and contains lengthy discussions relating to the installation of piles and caissons and the drainage and waterproofi  ng  of substructures. The IBC also requires engineering design of retaining walls.

In all, the building code attempts to ensure that every building will rest upon secure foundations and a dry substructure.

Figure 2.5                                         Presumptive surface bearing values of various soil types,                                                                 from  symbols  the 2006 IBC. Classes 3, 4, and 5 refer to the soil group in Figure 2.2.

Figure 2.2 The Unifi ed Soil Classifi cation System, from ASTM D 2487. The group symbols are a universal set of abbreviations for soil types, as seen for example, in Figure 2.8.

Figure 2.8 A typical log from a soil test boring indicating the type of soil in each stratum and the depth in feet at which it was found. The abbreviations in parentheses refer to the Unifi ed Soil Classifi cation System, and are explained in Figure 2.2.