Soil nailed walls or nailing is an in-situ reinforcement method with installed steel bars that retains an top to bottom excavated wall. Bars are usually installed in boreholes located on the wall of the earth, which are filled with cement grout in order to prevent corrosion of the bar and proper transfer of forces between the soil body and bar. This operation provides a stable reinforced wall that has the ability to retain soil.
This method was first discussed in 1960. Soil nailing is based on the method of rocks anchorage. For the first time, this stabilization system was used for tunneling in Australia in 1960. In this tunnel, steel bar reinforcement, injected cement grout and shotcrete was used to for tunnel stabilization. In the next years, this technique spread over the world. In Iran, use of this method has developed considerably in recent years and is one of the most practical methods, especially in urban construction.
In scientific principles of geotechnical engineering, soil nailing method acts in a passive manner and applies it’s effect through the interaction of soil-reinforcement due to the appearance of deformation in the soil. Hence, the use of a soil nailing system in situations where the sensitivity to the displacement caused by the excavation is high or in the vicinity of sensitive and old structures, or in soft and medium hardened soils, is not recommended generally.
Soil nailing is a new method which, due to its economic and unique advantages, is considered as a very suitable solution in various cases, such as stabilization of slopes and trenches, increasing load capacity and limiting changes in earth surface by projects. The use of this soil reinforcement method has been widely used in most of the developed and developing countries in the last two decades to stabilize excavations and natural slopes. Some of the vast applications of this method of soil reinforcement is to include the stabilization of natural slopes and/or trenches adjacent to the roads, expansion of roads, excavation in the vicinity of existing structures, stabilization and retrofitting of old retaining structures.