At a major hydropower station in a mountainous region of Southeast Asia, engineers confronted unstable slopes composed of fractured granite, clay seams, and active groundwater seepage. The station, with an installed capacity of 1,200 MW, is a cornerstone of the national renewable energy strategy. Its slope stabilization works covered approximately 25,000 square meters, with cut heights reaching 80 meters. Conventional anchoring methods, which require pre-drilled holes and separate grouting, proved inefficient because the holes frequently collapsed before the anchor could be inserted. The site's remote location at an elevation of 1,200 meters above sea level further complicated logistics, as all materials had to be transported via temporary access roads and narrow working benches limited the size of drilling equipment. SupAnchor, a recognized soil nail system manufacturer and ground anchor bolt factory, supplied its Grade 75 self-drilling hollow anchor bars as part of an integrated self drilling anchor system to address these challenges.
The self drilling anchor system uses a hollow bar that simultaneously drills, injects grout, and becomes the anchor itself—eliminating the need for casing and reducing installation steps. SupAnchor's hollow bar anchor technology, also known as a drill-and-grout bolt, enabled crews to advance through loose overburden and fractured rock at a rate of 15 to 20 anchors per shift, compared to fewer than five with traditional methods. This efficiency proved critical for meeting the project's tight construction schedule ahead of the rainy season, and the lightweight modular components allowed crews to maneuver in tight spaces without sacrificing performance.
SupAnchor's Grade 75 self-drilling hollow anchor bars are manufactured in accordance with ASTM A615 standards, ensuring uniform mechanical properties and predictable behavior under load. The bars feature a continuous T-thread profile, which provides a relatively higher rib area than conventional solid threaded bars. This design significantly improves bond strength between the steel and the cementitious grout, enhancing the overall performance of the geotechnical reinforcement system.
Key mechanical properties of the Grade 75 bars are summarized below:
| Property | Value |
|---|---|
| Yield Load | Approx. 147 kN (33 kips) |
| Ultimate Load | Approx. 196 kN (44 kips) |
| Elongation | ≥ 6% (ASTM A615) |
| Weight | Approx. 2.6 kg/m (1.75 lbs/ft) |
| Thread Orientation | Left-hand thread |
The yield load of 147 kN and ultimate load of 196 kN provide a safety factor of approximately 1.33, which is suitable for both temporary and permanent slope support when combined with appropriate anchor spacing and grout strength. The elongation of at least 6% indicates ductile behavior, allowing the bars to absorb energy through plastic deformation under extreme loading—an important characteristic for projects in seismically active regions. The left-hand thread orientation is fully compatible with SupAnchor's R and T thread self drilling anchor bolt products, enabling seamless integration into existing anchoring systems.
During installation, rotary-percussive drilling rigs drove the hollow bars into the slope while simultaneously pumping cement grout through the bar's core. The grout filled voids, bonded the bar to the surrounding ground, and stabilized the borehole wall. Pull-out tests confirmed that the anchors consistently achieved design loads with minimal displacement, and the T-thread's high rib area contributed to a robust mechanical interlock that resisted creep over time. The modular nature of the system allowed crews to couple multiple bar sections to achieve lengths of up to 12 meters, reaching beyond the critical slip surface without the need for specialized equipment.
The versatility of SupAnchor's Grade 75 hollow bar anchor extends far beyond hydropower slope stabilization. These self drilling anchor bolts are equally suited for tunneling, foundation underpinning, and mining applications where ground conditions are variable or access is restricted. Because the bar acts as both the drill rod and the anchor, it eliminates the need for temporary casing in collapsing soils, reducing equipment requirements and improving worker safety.
Key advantages observed on the project included:
For the hydropower station, the self drilling anchor system provided a robust solution for slope angles exceeding 60 degrees. The ability to install long anchors through overburden and fractured rock ensured that the stabilization zone extended well beyond the critical slip surface, effectively preventing shallow and deep-seated failures. SupAnchor also supplies a full range of accessories, including drill bits, couplers, and centralizers, forming a complete geotechnical reinforcement system that adapts to changing ground conditions without sourcing components from multiple suppliers.
Globally, aging infrastructure and the transition to renewable energy are driving significant investment in hydropower, transportation tunnels, and urban underground space. These projects frequently encounter difficult geology that traditional anchoring methods cannot handle efficiently. SupAnchor's self drilling anchor system offers a reliable, cost-effective alternative that meets international standards and accelerates project delivery. According to industry reports, the global market for ground anchors and soil nails is projected to grow at a compound annual growth rate of 5.8% through 2030, driven by infrastructure rehabilitation and mining expansion. SupAnchor's products are already used in over 40 countries, including high-profile metro projects in Europe and open-pit mines in Australia.
The use of ASTM A615-compliant steel ensures that the Grade 75 bars meet recognized material specifications, facilitating acceptance by engineers and regulatory bodies in North America and Europe. This is particularly important for cross-border projects where compliance with multiple codes is required. In Europe, the emphasis on sustainable construction and reduced carbon footprints aligns with the efficiency of self-drilling anchors. By minimizing drilling fluid waste and energy consumption, the technology supports green building certifications such as LEED and BREEAM, contributing to safer and more resilient infrastructure while lowering total project lifecycle costs.
SupAnchor has established itself as a leading provider of self drilling anchor bolt products through continuous research and development. The company's ISO 9001-certified manufacturing processes ensure that every Grade 75 bar is produced with consistent mechanical properties and thread geometry. Independent testing laboratories verify tensile strength, elongation, and chemical composition, providing confidence to project owners and consultants. In addition, SupAnchor's hollow bar anchors carry CE certification, enabling their use in European Union infrastructure projects.
SupAnchor's R&D center in Nanjing, China, focuses on metallurgical improvements and thread design optimization, holding multiple patents for self-drilling anchor technology. In the hydropower station project, SupAnchor's technical team collaborated closely with the contractor to optimize drilling parameters and grout mix design, helping to overcome unexpected groundwater inflows and reduce overall project risk. This professional, innovative, and collaborative approach underscores the company's commitment to engineering excellence.
Looking ahead, SupAnchor is expanding its product range to include corrosion-resistant coatings and high-capacity hollow bars for deep foundations. The company's global logistics network ensures timely delivery to remote project sites, reinforcing its reputation as a dependable partner in geotechnical engineering.
In conclusion, SupAnchor's Grade 75 self-drilling hollow anchor bars delivered measurable performance in a challenging hydropower slope stabilization project. Their high bond strength, compatibility with existing systems, and adherence to ASTM A615 standards make them a preferred choice for engineers seeking robust and efficient geotechnical reinforcement solutions in complex ground conditions.
A major infrastructure project leverages SupAnchor's self drilling anchor system to overcome difficult ground conditions, highlighting the technical advantages of hollow bar anchors in geotechnical reinforcement.
SupAnchor's Grade 75 self-drilling hollow anchor bars, compliant with ASTM A615, deliver high bond performance and compatibility for geotechnical reinforcement in challenging hydropower slope stabilization projects.
A European infrastructure project leverages SupAnchor's self drilling anchor system to overcome unstable geology, highlighting advanced geotechnical reinforcement technology and industry impact.
SupAnchor unveils the SupFRP® GFRP Friction Bolt, a lightweight, corrosion-resistant alternative to steel bolts for underground mining, tunneling, and slope stabilization. Key specs: 50mm diameter, 350kN load, 2.0 g/cm³ density.
SupAnchor's self drilling anchor bolts provide reliable geotechnical reinforcement for a large-scale tunneling project, overcoming difficult ground conditions and ensuring safety and efficiency.
