What Is Self-drilling Hollow Rock Bolt?

When it comes to rock bolt, most engineers are very familiar with it. The rock bolt develops from rebar, anchor line to ordinary hollow rock bolt, self-drilling hollow rock bolt. It usually was employed in the construction of foundation support, slope reinforcement, and tunnel pre-support. The construction efficiency increases along with the development of the rock bolt. Today, Sinorock will introduce you the self-drilling hollow rock bolt.

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Obviously, it is a kind of hollow rock bolt. The self-drilling hollow rock bolt can drill and grout simultaneously when processing. That’s the reason why it is called self-drilling. In addition, it possesses all the features that traditional hollow rock bolts do.

The self-drilling hollow rock bolt will drill deeply enough to anchoring in the hard rock, and then grout to fill in the drilling hole. In general, the self-drilling hollow rock bolt won’t provide a pre-stress. However, once the rock mass moves, it can develop a restraining force to counter the rock mass.


A set of self-drilling hollow rock bolt consists of a sacrificial drill bit (various types available for different conditions), a steel hollow bar (a path to grout), a coupler (to extend the hollow bar), a plate, and a nut. We also provide the drill bit adapter if the hollow bar doesn’t match your drill rig.


The self-drilling hollow rock bolts are divided into two patterns, R thread and T thread. Now, let me introduce them respectively.

R thread: Its thread complies with the international standard ISO 10208, which can match different drilling rigs.

T thread: The thread contains an arc-shaped part and a flat part. Thus, the cement slurry will bond better to the steel hollow bar to enlarge the bonding force.


Self-drilling hollow rock bolt combines drilling, grouting and anchoring together into one step. Casing pipe is omitted in the construction process, which greatly improves the construction efficiency.

Self-drilling hollow rock bolt has a rich variety of drill bits, which can be selected according to the properties of rock and soil to improve the drilling efficiency.

Self-drilling hollow rock bolt can fill cracks, consolidate rock mass and soil layer through pressure grouting, and has good grouting spreading radius and reliable anchoring quality.

The hollow bar can be cut at any position. Therefore, self-drilling anchor bolt is suitable for the construction in the narrow space which the large equipment cannot enter. Also, it can be lengthened by the coupler to meet the design depth.

Suitable Conditions

Self-drilling hollow rock bolt is suitable for the broken rock formation, loose soil ground, and conditions alike which are difficult to drill holes or where the drilling holes collapse easily, such as weathered rock, stone walls, rubble, chalks, marls, fills, competent ground and so on.


Tunnel and Underground Project

Self-drilling hollow rock bolt is mainly used for initial support of tunneling. High pressure grouting is achieved through the hollow bar to strengthen the soil or rock mass to ensure the surface stability. According to the types of support in the tunnels, self-drilling hollow rock bolt can be divided into fore piling, radial support, tunnel-face support, locking the foot support and reinforcement of the tunnel portal.

Slope Stabilization Project

Self-drilling hollow rock bolt is mainly used for slope project with poor geological environment. Slope stabilization is ensured by the entire anchoring system itself subjected to tensile and shear forces. It can be used as soil nail support, slope protection barrier, falling rock protection, retaining wall, embankment stability, roadbed reinforcement and other different application scenarios.

Rock bolts Application - Hollow Rock Bolts Application - Self drilling Hollow Rock Bolts Application - Sinorock

Ground and Foundation Project

Self-drilling hollow rock bolt is mainly used for micro pile. Pressure, tension or periodic loads can be transferred to the surrounding soil, transferring structural loads to the underlying foundation structure and limiting the deformation of the building. It can be used as new building pile foundation, existing building structure repair, tower foundation, bridge reinforcement, soundproof wall foundation, protective screen pile foundation, anti-floating pile foundation, retaining beam anchoring and other different structural scenes.

Now you know much about the self-drilling hollow rock bolt. If you are interested in the products, please feel free to contact us at sinorock@sinorockco.com to get a perfect solution to your project.

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