Build-in-resin Prestressed Self Drilling Hollow Bolt

Build-in-resin prestressed self drilling hollow bolt has been widely applied in tunneling and will be gradually extended to mining, slope stabilization, etc. It is especially suitable for anchoring the vault that is prone to collapse. It has the following advantages:

1.Embedded resin capsules with tapered resin outlet anchor head:

Solve the problems such as resin capsules falling down from vault construction and difficulty in resin capsules propulsion in slightly collapsed holes, ensuring that the resin capsules are pushed to the bottom of the hole accurately, reliably and completely.

2.Two-step process:

Built-in blade to thicken the anchor rod body:

Reduce the process of resin capsules into the anchor hole, suitable for all types of construction machinery and operation methods, which can realize the mechanization of the whole process of bolt construction and can significantly improve the work efficiency. A single bolt construction time is no more than 4.5 minutes.

3.Built-in blade to thicken the anchor rod body:

Reduce the process of resin capsules into the anchor hole, suitable for all types of construction machinery and operation methods, which can realize the mechanization of the whole process of bolt construction and can significantly improve the work efficiency. A single bolt construction time is no more than 4.5 minutes. The resin is squeezed into the bottom of the anchor hole, and the capsule package remains in the rod, so the influence of capsule package on the anchoring performance is excluded. The optimized three paths matching is to improve the anchoring quality and to make the anchoring force reach more than 100kN.

Build-in-Resin Self Drilling Hollow Bolt System

The build-in-resin prestressed system from Onton is designed for projects that need rapid anchoring, reliable load transfer, and neat installation in complicated ground.
This self drilling hollow bolt combines drilling, grouting and prestressing inside one process, so contractors can work in broken rock, backfill, or limited-space galleries without changing tools. By integrating a build-in-resin element, the anchor reaches early strength quickly and keeps the bond stable even when surrounding ground is not uniform.

Advantages and Benefits in Use

The installation sequence is straightforward, which reduces training time for new crews. Early bond development lets the contractor move to prestress sooner, avoiding long idle periods. Because the build-in-resin hollow bolt drills and bonds through the same path, it is effective in gravels, fill, weathered rock, and interfaces where conventional rebar anchors struggle. When a site adds hollow bar micropiles beneath the same structure, the anchor network and the pile network share loads more evenly. That often leads to lower differential movement and better service performance over time.

Product Advantages

1.Integrated structure: The anchor is a hollow bar that works as both drill rod and grout conduit. This reduces the number of accessories and keeps the anchor path straight.
2.Build-in-resin enhancement: The build-in-resin material improves early bonding at the anchor head or designated section. This is useful when the surrounding ground has voids or water.
3.Prestress capability: After installation, the bar can be tensioned to deliver active support, which improves stability of rock faces, tunnel linings, and slope facings.
4.Adaptable connections: Couplers, plates and nuts are available to match different bolt lengths and installation angles, so the same self drilling hollow bolt system can be used across one site.

Operation Process

1. Setout and selection. Confirm anchor length, bit type, and torque range based on ground data. Choose the appropriate build-in-resin hollow bolt diameter and accessories such as couplers, plates, and nuts.
2. Drilling. Advance the hollow bar with the selected drill bit. Use air, water, or grout flushing to clear cuttings. Maintain steady feed and rotation so the bore follows the planned line.
3. Resin activation. During final rotations, engage the resin units associated with the build-in-resin hollow bolt. Mixing starts inside the bore. Keep rotation long enough to achieve uniform distribution around the bar.
4. Initial hold. Allow the resin to set to the specified handling strength. Do not disturb the bar during this window.
5. Prestressing. Fit the bearing plate and nut. Apply load using the approved procedure. Record torque or jack readings as required by the method statement.
6. Finishing and inspection. Protect exposed steel. Check alignment and document the as-built data. Where the anchor is part of a foundation package with hollow bar micropiles, verify compatibility of loads and clearances.

Application Scenarios

This system is suited to underground caverns, mine roadways, metro or highway tunnels, slope treatment, retaining walls, and underpinning in confined basements. In all these cases, access is limited and drilling must be done rapidly.
A self drilling hollow bolt with build-in-resin is especially useful on rock masses that include weathered layers, fills, or faulted zones where normal rebar anchors do not develop full bond. The same arrangement can also be applied to temporary support in foundation pits, pipe jacking launch shafts, or portal entrances.
Because the product integrates drilling and grouting, it can be used on reinforcement jobs where machine time must be reduced, or on rehabilitation works where existing linings cannot be heavily damaged.
Onton can supply the bars, bits, couplers and plates as a package, making it easier for site teams to keep one specification across the project. In this way the self drilling hollow bolt with build-in-resin becomes a repeatable anchoring solution rather than a one-off detail.