Self-drilling Anchor Bolt

Self-drilling anchor bolt integrates drilling, grouting, and anchoring into one, with a simple construction process, high construction efficiency, and good anchoring effect, which can effectively solve the problems of easy collapse and difficult hole formation during drilling. Therefore, it applies to a wide range of geological conditions, such as siltstone, miscellaneous fill, strongly weathered rock, pebble layer, and conglomerate layer.

Application fields

Self-drilling anchor bolt is a new type of support material, mainly used in tunnel and underground engineering, slope stabilization engineering, ground and foundation engineering, such as various slope support, foundation support, tunnel pipe umbrella support, foundation support of transmission towers or wind power towers, existing buildings and structures repair and reinforcement. It is used for temporary support and permanent support in the pre-project period, which can effectively enhance the own stability of soil and rock, and has become an indispensable material in geotechnical anchorage engineering.

Product advantages

1. It is suitable for all kinds of geological conditions.

Especially that are not easy to be constructed by traditional anchor construction techniques, such as geology prone to the collapse.

2. There is no limit to the drilling depth of self-drilling anchor bolts.

While conventional anchors have a relatively shallow drilling depth due to limitations in both anchor material and drilling equipment, self-drilling anchor bolts can achieve much greater depths thanks to their low drilling resistance.

3. Suitable for construction in narrow spaces.

The self-drilling anchor bolt’s length can be cut or extended as needed, with general specifications of 2m, 3m, 4m, and 6m.

4. Simple process.

Self-drilling anchor blots complete drilling, grouting, and anchoring in one drilling, simplifying the process and speeding up the construction.

5. It is beneficial to stabilize the hole wall.

The cement grout with a water-cement ratio of 0.4~0.5 is supplied under pressure by a screw grouting machine while drilling so that the grout fills the hole and the fissures of the geotechnical body rapidly and is absorbed and cured by the hole wall to ensure the stability of the hole wall.

1. Construction process of self-drilling anchor bolt

①Material preparation

Before using the self-drilling anchor bolt, check whether the drill bit and anchor bar are damaged. If problems are found, solve them promptly, and construction can start after they are normal. Then, assemble the hollow anchor bar with the drill bit to be used and prepare the coupler and anchor bar.

② Drilling and grouting

The drilling construction of self-drilling anchor bolts generally uses a special drilling rig for self-drilling anchor bolts, which can perform high-frequency impact and high-speed rotation to speed up drilling. During drilling, the rod and grouting hole are flushed with pressurized water or cement slurry prepared according to a certain water-cement ratio through the screw grouting machine to avoid being blocked by debris. Then use a screw grouting machine for grouting to achieve the effect of simultaneous drilling and grouting.

③Lengthening anchor bar

Usually, the length of the self-drilling anchor bolt is 3m, 4m, 6m, etc. If the drilling depth designed in the project is relatively deep, it is necessary to lengthen the rod with a coupler and then drill and grout.

④ Install plates and nuts

The plate and nut are essential accessories for the self-drilling anchor bolt, which installed at the end of the anchor bar. The plate goes between the nut and the rock to transmit the anchoring force of the hollow anchor bar to the plate. By applying preload, it presses against the rock surface to prevent any deformation.