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There are also a number of prefabricated modular wall systems in use. Such systems are generally composed of modules or bins filled with soil, and function much like gravity retaining walls. The bins may be of concrete or steel, and can be used in most cases where conventional gravity, cantilever, or other wall systems are […]

Evaluation of a global safety factor that includes the nailed soil and the surrounding ground requires determination of the critical sliding surface. This surface may be located totally inside, totally outside, or part inside and part outside the nailed zone. Limit equilibrium methods are usually used, and the Davis method is recommended because of its […]

The following typical details and design procedure are based primarily on Caltrans’ method for use on highway construction, but the method is very similar to other methods presently in practice. Design facing pressures are based on the French Clouterre empirical method. The cast-in-place portion of the facing is designed for this pressure for permanent FIGURE […]

The construction sequence is typically to excavate, nail, and shotcrete the face in increments from the top down. Figure 8.56 shows a schematic of a sequence for underpass widening. Where face stability is a concern, a flashcoat of shotcrete may be applied before nail installation. The most common method of nail installation in FIGURE 8.56 […]

The stability of a soil nailed structure relies on (1) transfer of resisting tensile forces generated in the inclusions in the active zone into the ground in the resistant zone, through friction or adhesion mobilized at the soil-nail interface, and (2) passive resistance developed against the face of the nail. Ground nailing using closely spaced […]

Almost all shotcrete failures in slope stabilization applications have resulted from inadequate drainage. Therefore, drainage is a critical design and construction element. Drainage from behind the shotcrete face can be provided by the following methods: 1. Surface interceptor ditch. Excavate a shallow ditch along the crest of the excavation to lead away surface water. Drainage […]

Soil nailed walls have some similarities with MSE walls but also some fundamental differences. The main similarities are: 1. The major mechanism in both MSE and soil nailed retaining structures is the development of tensile forces in the reinforcements due to frictional interaction and, consequently, restrainment of lateral deformations of the structures. 2. The reinforced […]

Most research to date has been done in homogeneous soils. However, there is no rea­son why the concept cannot be applied to heterogeneous soil masses if proper consid­eration of soil properties is made and rationally applied to the selection of nail length and spacing. To be economical, soil nailed walls should be constructed in ground […]

8.8.1 Development and General Considerations Figure 8.52 shows a cross-section of the first soil nailed wall, which was a temporary wall built in France (1972-1973) for a railroad project. Such walls are constructed from the top down during excavation. Reinforcing bars are either inserted in drilled holes and grouted into place, or driven into place. […]

Anchor design includes the selection of a feasible anchor system, estimation of anchor capacity, determination of unbonded length, and consideration of corrosion protection. In determining the feasibility of employing anchors at a particular location, considera­tions include the availability of underground easements, proximity of buried facilities to anchor locations, and the suitability of subsurface soil and […]