The Self-Drilling bolt is a fully threaded hollow bar that initially serves as a drill rod, utilizing a lost bit. The thread is made to comply to ISO 10208. For use in unconsolidated ground or other difficult ground conditions.
 

Advantages of self-drilling bolt

1. Suitable for all kinds of geotechnical conditions. SDA bolt has a better construction effect than those of common anchor bars, especially is used in complex geological conditions, such as easy-to-collapse geology.

2. Unlimited drilling depth. Due to the limitations of existing rock bolt materials and drilling equipment, the conventional rock bolt has a relatively shallow drilling depth, but the self-drilling rock bolt can drill deeper due to its small drilling resistance.

3. Suitable for construction in narrow spaces. The length of the single bolt can be cut or extended as required. Common specifications are 2m, 3m, 4m, and 6m.

4. Simple construction process. The self-drilling bolt can complete the drilling, grouting, and anchoring in one drilling, simplify the technological process and accelerate the construction speed.

5. It helps stabilize the hole wall. When drilling, the screw grouting machine is used to supply cement grout with a water-cement ratio of 0.4~0.5 under pressure, so that the grout can quickly fill the borehole and the rock and soil mass, and be absorbed and solidified by the hole wall to ensure the stability.

The self-drilling hollow bar anchor system is comprised of a hollow threaded bar attached with a drill bit that performs drilling, the hollow bar allows air and water to freely pass through the bar during drilling to remove debris, after drilling at the required depth is completed, grout fills the hollow bar through the pressure for their requirement and completely covers the entire bolt Coupler: The couplers can be used to join hollow bars and extend the bolt length, it means the anchor can be elongated with the couplers Plate and Nut: The plate and nut are installed according to their design requirement Drill Bit: The drill bit would be selected at the choice of ground condition



• Excellent for spiling (fore-poling)
• Bolt is drilled in and grout is pumped through the center hole with pumpable resin or cement grouts
• The couplers are designed to exceed the ultimate load of the bar by 20%. The couplers are designed to minimize the loss of drill energy
• Several drill bits are available. Most widely used is the EXX Tungsten carbide chisel bit
• Standard length is 3 m (9 ft -10 ft) - Longer lengths are available: 4 m, 6 m
• Galvanized option under ASTM A123

Application

Self drilling anchor system is mainly used in slope stabilization, tunneling pre-support, foundations with micropiles, it is also widely used in the railway system, metro project etc. It can be installed in sites with weak rocks, loose soil, weathered layer, sand with stone layer and so difficult to create a hole in complex formations. The unconsolidated ground condition favor the self-drilling anchor bolt technique for fast and simple method of installation compared to the traditional method.