What is a self-drilling anchor? A self-drilling anchor is an advanced support material that integrates drilling, grouting, and anchoring functions. Its hollow rod design allows for simultaneous drilling and grouting, making it particularly suitable for geological conditions such as fractured rock and loose soil, where traditional anchors struggle. Its core technology combines the drill rod and anchor into one, resolving engineering challenges such as hole collapse and shrinkage, significantly improving support efficiency and safety.

   Its core features can be summarized in three points: First, its integrated structure: the rod serves as both the drill rod and anchor, reducing the number of construction steps. Second, its adaptability allows it to operate in loose, fractured, and prone-to-hole-collapse geology, avoiding the issue of traditional drilling followed by hole collapse that can prevent anchor installation. Third, its reliable anchoring: the grouting material passes directly through the hollow rod to the bottom of the hole, fully filling the gap between the hole wall and the rod, creating a uniform bond and enhancing support stability.

   I. Core Structure and Working Principle

   1. Structural Components

   ① Hollow Rod: A high-strength alloy steel tube (tensile strength ≥650 MPa) with a continuously threaded surface, serving as both a drill rod and a grouting channel.

   ② Drill Bit: Made of alloy or all-steel (e.g., cross-shaped or ball-toothed), the drill bit is adapted to the rock formation hardness. The diameter is typically 2-3 times the diameter of the drill hole.

   ③ Auxiliary Components: Connecting sleeve (to extend the rod), centering device (to ensure uniform grouting), backing plate, and nut (to transfer stress).

  2. Functions of Drill Anchor Bolts

   ① Wedging: Penetrates rock discontinuities, suppressing displacement of the surrounding rock.

   ② Suspension: Anchors the fractured surface layer to the stable rock formation.

   ③ Composite Beam: Multiple rock formations form a monolithic beam structure, enhancing bending strength.

   ④ Extrusion Reinforcement: Adjacent anchor bolts form an arched compression zone, increasing the bearing capacity of the surrounding rock.

   ⑤ Prestress Control: Actively applies tension to balance downward force on the slope.

   II. Core Application Scenarios

   ① Slope Support: After grouting, the rods form frictional bonds with the rock and soil, inhibiting deformation and effectively preventing collapse in sand and gravel layers.

   ② Foundation Pit Support: Bonding friction constrains soil deformation, passively stabilizes the pit under tension, addresses shrinkage and sand flow, and improves pullout resistance.

   ③ Tunnel Pipe Roof: Advanced support forms a bearing arch, reducing surface settlement and doubling efficiency in V/V grade surrounding rock.

   ④ Micropile Foundation: Reinforces foundations through down-drilling and grouting, particularly for wind turbine towers and bridge pile foundations.

   III. Advantages Compared to Traditional Anchor Bolts

   ① Geological Adaptability: No casing is required in collapse-prone formations such as backfill, gravel layers, and fault zones.

   ② Construction efficiency: Drilling-grouting-anchoring is completed in one go, with a shift efficiency of 130-250 meters (2-4 times higher than the traditional process).

   ③ Cost control: It can be operated by 3 people, with a 30% reduction in labor costs and a lower overall cost than the pipe drilling process.

   ④ Quality assurance: The centering device ensures uniform grouting, significantly improving corrosion resistance and anchoring strength.

   Self-drilling anchors, with their advantages of "integrated construction, strong adaptability, and high reliability", have become one of the core technologies for solving complex geotechnical engineering support problems. With their geological adaptability and construction efficiency, they have become the preferred support solution for complex geotechnical engineering. As infrastructure extends to the difficult and dangerous areas in the west, their application potential in disaster prevention and control (such as landslides and foundation settlement) will be further released [[5][10][14]()]. In the future, it is necessary to continuously optimize material properties and intelligent construction systems to meet the strategic needs of my country's "deep earth development".