<P>Soil nailing is an <I>in situ</I> soil reinforcement technique that can be used to enhance the stability of slopes, retaining walls, embankments, and excavations. It involves installation of closely spaced, relatively slender unstressed tension-carrying structural elements into the ground to stabilize the soil mass. These elements, which are called soil nails, comprise steel or other engineering materials such as fiber reinforced polymer. </P><P>Soil nailing did not gain popularity until the 1970s when engineers started to realize that the technique could offer an effective, robust, and economical reinforcing system for a variety of ground conditions. More importantly, the track record has been excellent in that no major collapses have been reported in properly designed and well-constructed soil nailed structures so far. Considerable experience and knowledge of the technique have been gained in the past few decades through systematic technical development work comprising laboratory