Self-drilling soil nail is a method of rock soil reinforcement. It has a full-length thread on its outer surface, coupling can lengthen anchor bar and the disposable drill bit is installed at its front.

Because of its special structure, self-drilling soil nail has several advantages:

• High efficiency: self-drilling soil nail combines drilling, grouting, and anchoring together, which decreases the working procedure and improves working efficiency.
• Extensive application: self-drilling soil nail is suitable for stratum which is difficult to drill holes, such as weak and broken surrounding rocks, where is difficult to insert soil nail and easy to collapse. After drilling, anchor bar stays in the hole and doesn’t need to be pulled out. It saves time, decreases difficulties, and avoids collapse.
• Strong adaptability: thread is over the surface of anchor bar. It can be cut at any section according to different construction conditions.
• High anchorage force: the thread of self-drilling soil nail includes R-type and T-type, which combines with grouting materials and then has good adhesiveness, high anchorage force.
• Good anchoring effect: cement slurry is grouted from top to bottom, which is sufficient and dense, so the quality of anchoring is quite good.
• Simple and convenient construction: compared with common anchor bars, self-drilling soil nail has decreased the procedures of installing anchor bar, inserting injection pipe, which is simple and convenient for workers to operate.