In a major infrastructure project in the Alps, engineers faced a daunting challenge: a tunnel through loose, water-saturated soil that threatened to collapse the face with every advance. Traditional rock bolts required separate drilling and grouting steps, slowing progress and increasing risk. Enter the SupAnchor® GFRP SDA Bolt—a hollow bar anchor system that combines drilling, grouting, and anchoring into a single, efficient operation. This innovative self drilling anchor system is already transforming how contractors manage soft ground conditions worldwide.
The SupFRP® GFRP SDA Bolt represents a leap forward in geotechnical reinforcement. Designed for permanent applications, it is crafted from glass-fiber-reinforced polymer (GFRP), providing exceptional corrosion resistance and cuttability—a critical advantage when tunnel boring machines (TBMs) or roadheaders must pass through bolted sections without damaging cutting tools. Its central hollow core permits water flushing during drilling and subsequent grout injection, ensuring a clean borehole and a strong bond even in water-saturated or collapsing ground.
Contractors and design engineers require reliable technical data to specify anchor systems. The GFRP SDA Bolt is available in four ISO-standard thread profiles—R25, R28, R32, and R38—each suited to varying load demands. The following table summarizes key performance indicators for each model:
| Property | H25S | H28S | H32S | H38S |
|---|---|---|---|---|
| Outside Diameter (mm) | 25 | 28 | 32 | 38 |
| Internal Diameter (mm) | 12 | 14 | 15 | 20 |
| Guaranteed Tensile Load (kN) | 220 | 280 | 365 | 490 |
| Tensile E-Modulus (GPa) | 45 | 45 | 45 | 45 |
| Torsion Strength (Nm) | 180 | 250 | 360 | 450 |
| Ultimate Strain (%) | 2.0 | 2.0 | 2.0 | 2.0 |
| Weight (kg/m) | 0.63 | 0.86 | 0.99 | 1.33 |
| Thread Type (ISO) | R25 | R28 | R32 | R38 |
With guaranteed tensile loads ranging from 220 kN to 490 kN and torsion strengths up to 450 Nm, these bolts withstand high installation torque and demanding service loads. The GFRP material’s tensile modulus of 45 GPa delivers controlled elongation, absorbing ground movements without brittle failure—a key requirement in squeezing ground. The hollow bar design, with internal diameters from 12 to 20 mm, ensures efficient grout flow, while the lightweight nature (as low as 0.63 kg/m) eases handling and reduces transportation costs. The waved thread profile enhances bond strength by providing a mechanical interlock with the grout, improving load transfer from the ground to the anchor. This design, combined with the high torsion resistance, allows the bolt to be drilled into dense soils without buckling—a common failure mode for lesser products.
The self drilling anchor bolt excels in scenarios where conventional drilling is impractical. In tunneling face stabilization, it is driven directly into the soil without casing, using a sacrificial drill bit. As the bolt advances, water flushing through the central hole removes cuttings, preventing clogging. Once at depth, grout is injected through the same channel, filling voids and forming a bonded anchorage in minutes. This drill-and-grout bolt technique is especially effective in soft rock and clay, where stand-up time is limited. For forepoling, the ability to install bolts quickly at the tunnel face buys critical time for primary lining installation. The system’s modularity means bolts can be coupled to achieve lengths up to 11 meters, adapting to varying overburden depths.
In slope stabilization, the system reinforces potentially unstable slopes without the need for pre-drilled holes. Contractors report a 40% reduction in installation time compared to traditional methods, a critical advantage when weather windows are tight. The cuttability of GFRP allows for later re-excavation or reshaping without damaging machinery, making it a preferred choice in mining and civil projects where future access is required.
The growing demand for underground infrastructure—from metro systems in congested cities to hydropower tunnels in remote regions—calls for reliable, rapid ground support solutions. The hollow bar anchor market is projected to expand as mining and construction firms seek to lower cycle times and improve safety. SupAnchor’s GFRP SDA Bolt directly addresses these trends, offering a corrosion-free, high-strength alternative to steel in aggressive environments. Its ISO-standard threading ensures compatibility with global drilling equipment, simplifying logistics for international projects. Environmental benefits are also noteworthy: GFRP is non-corrosive, eliminating the need for cementitious coatings and reducing the carbon footprint. Its longevity in permanent installations cuts maintenance and replacement costs over the structure’s lifespan.
By eliminating the separate grouting step and reducing the number of components, the system also lowers the risk of human error and enhances overall workplace safety. As a soil nail system manufacturer, SupAnchor has integrated feedback from field engineers to refine the bolt’s waved thread structure, which improves load transfer and mechanical interlock. This innovation has been validated in pilot projects across Europe and North America, where it has outperformed conventional anchors in terms of both speed and long-term reliability.
With decades of ground anchor bolt factory experience, SupAnchor has become synonymous with quality and ingenuity in geotechnical engineering. The company’s R&D team continuously pushes boundaries, as seen in the GFRP SDA Bolt’s advanced composite manufacturing. Adhering to rigorous ISO standards, SupAnchor ensures that every product meets the highest performance benchmarks. With ISO 9001-certified production facilities and a track record of successful deliveries to projects like the Brenner Base Tunnel and the Cross Island Line, the company demonstrates the reliability that global contractors trust. Its global network of partners and technical support teams provides on-site training and customized solutions, embodying the brand’s core values of professionalism, innovation, and collaboration.
As the industry moves toward more sustainable and resilient construction practices, SupAnchor’s self drilling anchor system stands out as a versatile, cost-effective tool for tackling the toughest ground conditions. Whether reinforcing a tunnel face in soft clay or securing a mountain slope, the GFRP SDA Bolt delivers the performance and peace of mind that engineers demand.
SupAnchor's self-drilling anchor system played a key role in stabilizing a challenging slope along a major European transportation corridor, showcasing advanced geotechnical reinforcement solutions.
SupAnchor's GFRP SDA bolt integrates drilling, grouting, and anchoring in one step, providing high tensile strength and corrosion resistance for tunneling and slope stabilization.
SupAnchor's self-drilling anchor bolt provides efficient ground stabilization for a critical retaining wall project, demonstrating advanced geotechnical reinforcement in adverse conditions.
SupAnchor’s SupHulk® PM series friction bolts provide instant load-bearing, full-length anchorage, and high deformability. With breaking loads up to 240 kN, they are ideal for mining and tunneling in challenging rock conditions.
A highway widening project in mountainous terrain deploys SupAnchor's self drilling anchor system to combat fractured geology, ensuring long-term stability with advanced corrosion protection and high tensile strength.
