R38 Self-Drilling Hollow Rock Bolt for Slope and Tunnel Support
R38 self-drilling hollow rock bolt for slope, tunnel and fractured rock support. Typical R38N reference values include 38 mm nominal diameter, 400 kN yield load and 500 kN ultimate load.
| Designation | R38N hollow self-drilling anchor bar |
| Outer Diameter | 38 mm |
| Typical Inner Diameter | 19-21 mm depending on variant |
| Typical Yield Load | About 400 kN reference value |
| Typical Ultimate Load | About 500 kN reference value |
| Typical Weight | About 5.3-6.0 kg/m depending on supplier and variant |
| Thread Type | Continuous R-thread hollow steel bar |
| Common Applications | Rock bolting, slope stabilization, tunnel face support, excavation reinforcement |
R38 hollow self-drilling rock bolt for stronger slope stabilization, fractured rock support, tunnel face reinforcement and excavation works requiring more capacity than R32.
Product Overview
R38 self-drilling anchor bar is positioned between general R32 soil nails and heavier R51 anchor systems. It is often selected when the project needs stronger reinforcement without moving to larger drilling equipment.
The hollow bar drills directly into broken rock, weathered zones or mixed ground with a sacrificial bit. Grout is injected through the bar to create load transfer between the threaded steel and surrounding ground.
R38 is practical for slope stabilization, tunnel support, rock bolting and excavation works where ground is more demanding than shallow soil nailing.
Technical Specifications
| Designation | R38N hollow self-drilling anchor bar |
|---|---|
| Outer Diameter | 38 mm |
| Typical Inner Diameter | 19-21 mm depending on variant |
| Typical Yield Load | About 400 kN reference value |
| Typical Ultimate Load | About 500 kN reference value |
| Typical Weight | About 5.3-6.0 kg/m depending on supplier and variant |
| Thread Type | Continuous R-thread hollow steel bar |
| Common Applications | Rock bolting, slope stabilization, tunnel face support, excavation reinforcement |
Product Image Gallery
Real images from the current Self Drilling Anchor media group, used to show bar body, thread profile, hollow grouting rod and accessory details.
Applications and Real Ground Conditions
Fractured rock support
R38 is suitable for broken rock where a conventional open borehole may collapse.
Slope stabilization
Used for stronger soil nails and rock bolts in road, railway and mine slopes.
Tunnel face bolting
Provides higher capacity than R32 for weak headings and mixed-face excavation.
Retaining works
Works with bearing plates and shotcrete facings in excavation support systems.
Performance Advantages
Higher capacity than R32
Useful when moderate anchors are not enough for the design load.
Still practical to drill
R38 is stronger while remaining manageable for many anchor drilling rigs.
Good grout bonding
Continuous thread improves interaction between steel bar and grout body.
Adaptable accessories
Can be supplied with suitable drill bits, couplers, nuts, plates and centralizers.
Selection Guide
Choose R38 when the project needs a stronger self-drilling hollow bar than R32 but does not require the heavy capacity of R51 or T76 systems.
| Use R38 | Fractured rock, stronger slope nails, tunnel support and excavation reinforcement. |
|---|---|
| Use R32 | General soil nailing where R38 capacity is unnecessary. |
| Use R51 | Heavy slopes, longer anchors or micropile-style support. |
| Bit selection | Use carbide or cross bits for weathered and fractured rock. |
Quality Control and Installation Checks
Material verification
Confirm nominal diameter, internal diameter, wall thickness, weight, yield load and ultimate load against the order specification and mill certificate.
Thread and coupler fit
Check thread profile, coupler engagement, nut fit and bearing plate compatibility before dispatch.
Grouting records
On site, record grout mix, pressure, volume, return flow and curing time because bond quality controls final anchor performance.
Installation traceability
Track installed length, drilling depth, bit diameter, coupler quantity and anchor location for each support point.
Export Packing and Matched Accessories
Matched system supply
Bars can ship with sacrificial drill bits, couplers, nuts, bearing plates and centralizers according to the bill of materials.
Export bundles
Bundles are prepared for container loading, sea freight and jobsite handling.
Length options
Standard and project-specific lengths can be supplied; couplers support staged installation in restricted work areas.
Documents
Packing list, commercial invoice, mill test certificate and inspection records can be prepared according to order terms.
Why Choose SunSea Steel
- Real anchor product images from the current media library, not placeholder stock images.
- Specification-based quotation covering bar, drill bit, coupler, nut, plate and centralizer.
- Support for R25, R32, R38, R51, T76 and project-specific hollow bar systems.
- Export-oriented packing and documentation for international ground engineering buyers.
- Professional communication around design load, ground condition, grout plan and installation method.
- Contact-ready CTA with email and WhatsApp template variables.
Frequently Asked Questions
What is R38 self-drilling hollow rock bolt used for?
It is used for fractured rock support, stronger slope stabilization, tunnel face bolting and excavation support.
How does a self-drilling anchor work?
The hollow threaded bar acts as the drill string during installation. Cement grout is pumped through the hollow core and the same bar remains in the ground as the reinforcement tendon.
Why use a hollow bar instead of a conventional solid bar anchor?
A hollow bar system reduces the need for a stable open borehole before tendon insertion, which is useful in loose soil, fractured rock, fill and water-bearing ground.
What load information should be checked?
Typical R38N reference values are about 400 kN yield load and 500 kN ultimate load, subject to supplier documentation and project design.
How should the correct anchor size be selected?
Select R38 when R32 is too light but R51 is not required; confirm drilling equipment, ground condition, bit type and grout plan.
Which accessories are normally required?
A complete system normally includes sacrificial drill bit, coupler, nut, bearing plate and centralizer matched to the bar thread.
Can the product be used for permanent works?
Permanent works require project-specified corrosion protection, full grout cover and inspection records. Hot-dip galvanizing or other coatings can be discussed when required.
What information is needed for quotation?
Send bar size, length, quantity, design load, ground condition, drill bit type, plate size, corrosion protection requirement and destination port.
Request Technical Support and Quotation
Send anchor size, length, quantity, design load, ground condition, drill bit type, plate size, corrosion requirement and destination port. We will match the bar, bit, coupler, nut, plate and centralizer as a complete self-drilling anchor system.