Rigid retaining walls are those that develop lateral resistance primarily from their own weight. Figure 8.20 shows the terms used in the design of this type of wall. On the basis of their overall cross-sections, those walls may be referred to as L walls or T walls. (See insets, Fig. 8.3.)
Pennsylvania Department of Transportation, Harrisburg, Pa., with permission)
Examples of rigid structures typically include concrete gravity walls, thick concrete slurry walls, and gabion walls. Additionally, some Reinforced Earth walls, if designed to be reinforced in such a way that limited lateral movement will occur, can also be categorized as rigid walls. In fact, a wall may have considerable flexibility in its vertical dimension and nevertheless be classified and designed as a “rigid” wall system. Requirements for resistance of these wall types include sliding stability, overturning, bearing pressure evaluation, and settlement considerations. Design criteria for rigid retaining walls are summarized in Fig. 8.21. Overall, or global, stability is an important consideration in that, while the wall itself may adequately retain a soil mass, the soil mass may be unstable because, for example, of a deep-seated failure plane. This type of consideration is evaluated by slip circle analysis.