In a remote mountainous region, a major hydropower station expansion faced a daunting geotechnical challenge. The construction of new access roads and powerhouse foundations was threatened by steep, fractured rock slopes. Loose overburden and highly weathered bedrock demanded a fast, reliable anchoring solution that could adapt to unpredictable ground conditions. Project engineers selected SupAnchor\'s Grade 75 self-drilling hollow anchor bars—a high-performance component of an advanced self drilling anchor system—to stabilize the slopes and ensure long-term safety.
The site geology consisted of alternating layers of weathered schist and basalt, with groundwater seepage adding to the complexity. Conventional drilling methods risked borehole collapse and grout washout, leading to schedule delays and cost overruns. The drill-and-grout bolt technique offered a streamlined alternative: a single pass installs a fully grouted anchor, even in collapsing ground, without the need for temporary casing.
The Grade 75 hollow bar anchor features a continuous left-hand T-thread design, which provides a relatively higher rib area compared to conventional threads. This enhances the bond strength in grouted applications, making it a superior geotechnical reinforcement system for soil and rock anchoring. The bars are fully compatible with SupAnchor\'s existing R and T thread product lines, allowing seamless integration into ongoing operations.
| Property | Specification |
|---|---|
| Grade | 75 (ASTM A615) |
| Yield Load | 147 kN (33 kips) |
| Ultimate Load | 196 kN (44 kips) |
| Elongation | ≥ 6% |
| Weight | 2.6 kg/m (1.75 lbs/ft) |
| Thread Type | Left-hand continuous T-thread |
The 6% minimum elongation meets the ductility requirements for plastic deformation capacity, critical in dynamic environments like hydropower slopes where micro-seismic activity can occur. At 2.6 kg/m, the hollow bar anchor is lightweight enough for easy handling while maintaining high axial stiffness. The left-hand thread orientation ensures consistent tensioning and coupling, and its compatibility reduces inventory complexity for contractors.
On the slope stabilization project, the bars were installed using a self drilling anchor bolt technique. A rotary-percussive drill head drove the hollow bar through the overburden and into the competent bedrock. Grout was pumped continuously through the hollow core, filling the annular space and penetrating surrounding fractures, creating a monolithic reinforced zone. This hollow bar anchor application effectively transformed loose slope material into a stable composite mass, eliminating the need for costly excavation or additional support structures.
The hydropower slope project exemplified the versatility of the SupAnchor system. The site presented water seepage from underground aquifers, which could have compromised conventional drilled-and-grouted anchors. However, the simultaneous grouting action of the self drilling anchor system sealed the borehole walls immediately, preventing washout and maintaining grout integrity. This characteristic makes the system ideal for tunneling, mining, and foundation reinforcement in saturated ground.
Installation speed improved by over 30% compared to traditional methods, as the need for separate drilling and anchor insertion was eliminated. This efficiency is a hallmark of a reliable soil nail system manufacturer, and SupAnchor\'s quality control ensured every bar met stringent load test criteria. Post-installation pull-out tests confirmed design loads were exceeded, with minimal creep under sustained loading, providing the project team with confidence in the long-term slope stability.
Beyond the time savings, the system reduced the equipment footprint on the narrow mountain benches. A single drilling rig could install up to 20 anchors per shift, a rate nearly impossible with cased methods. The galvanized and epoxy-coated options available within the product line also offer extended corrosion protection for permanent applications, further widening the scope of use in aggressive environments.
With aging infrastructure and increasing extreme weather events, governments and contractors are investing in resilient retaining structures. Geotechnical reinforcement systems like these self-drilling hollow anchors play a vital role in safeguarding roadways, dams, and railways. As a recognized ground anchor bolt factory, SupAnchor supplies products that meet international standards, including ISO 9001 and CE certification, for projects in Europe, North America, and Asia.
The hydropower station case is part of a broader trend toward mechanized, time-saving ground improvement. By reducing reliance on heavy machinery and minimizing environmental disturbance, such systems align with sustainable construction practices. The success of the Grade 75 bars in this application highlights their suitability for both temporary and permanent works, from deep excavations to bridge abutments, and they are increasingly specified in design-build contracts that demand value engineering.
Driven by a philosophy of Professional, Innovative, Collaborative, SupAnchor invests heavily in R&D to refine its product offerings. The Grade 75 bar is a testament to responsive engineering—developed to meet the demand for higher-strength, compatible anchoring components that integrate effortlessly with existing site equipment. The company\'s global network of technical support ensures that each self drilling anchor bolt is selected and installed correctly, fostering successful outcomes on complex projects.
With over a decade of experience and a portfolio of patented threading profiles, SupAnchor has earned the trust of major contractors and consultants worldwide. From alpine tunnels in Switzerland to open-pit mines in Canada, the brand is synonymous with reliable ground control. The hydropower slope project stands as yet another example where SupAnchor\'s hollow bar technology delivered safety, speed, and savings—reinforcing its reputation as a partner for the world\'s toughest geotechnical challenges.
For more information on SupAnchor\'s complete range of self-drilling anchor systems, visit www.supanchor.com.
A high-profile transportation project in mountainous terrain has employed SupAnchor's self drilling anchor bolts, demonstrating the hollow bar anchor system's effectiveness in challenging geotechnical conditions.
SupAnchor's high-strength hollow anchor bars, with 147 kN yield load, provide a cost-effective, efficient geotechnical reinforcement system for challenging hydropower slope projects. Read the full project report.
A Rocky Mountain tunnel project uses SupAnchor’s self drilling anchor system to stabilize fractured rock, demonstrating the value of hollow bar anchors in geotechnical reinforcement.
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A recent European tunnel construction project successfully utilized SupAnchor's self drilling anchor system to overcome difficult geology, highlighting the efficiency and reliability of hollow bar anchors in modern geotechnical engineering.
