In a recent large-scale tunneling project through fractured granite formations, geotechnical engineers faced the challenge of providing immediate and reliable ground support to ensure worker safety and excavation stability. The project’s success hinged on a robust rock bolting solution that could be installed quickly and bear full load immediately. The engineering team selected the SupHulk® Friction Rock Bolt System from SupAnchor, a China-based global leader in self-drilling anchor systems. This decision underscored a growing trend in the mining and tunneling industries: the adoption of friction rock bolts that deliver high yield loads, exceptional deformability, and simple installation—all without the need for grout or resin.
SupAnchor’s SupHulk PM series represents the premium line of friction bolts, engineered for both mining and civil engineering applications where rock conditions demand stiff support with high load capacities. The three models—PM12, PM16, and PM24—offer a range of performance parameters to suit various geological challenges, making them a versatile tool for geotechnical reinforcement.
The SupHulk rock bolt operates on a simple yet highly effective principle: a sealed steel tube with a special inflation head is inserted into a drilled borehole. Using a dedicated inflation pump, water is injected to a pre-determined pressure, causing the tube to expand and press tightly against the borehole walls. This creates a full‑column friction and interlocking anchorage along the entire length of the bolt, providing immediate load‑bearing capacity. The system can be pull‑tested at any time to verify installation quality, and the pump automatically stops at the recommended pressure, ensuring consistent results with minimal operator error.
Key technical parameters for the PM series are summarized below, highlighting the balance between strength, ductility, and weight that enables these bolts to perform across a spectrum of ground conditions.
| Model | Min. Breaking Load (kN) | Min. Yield Load (kN) | Min. Elongation A100mm (%) | Inflation Water Pressure (bar) | Required Hole Diameter (mm) | Weight at 3m Length (kg) |
|---|---|---|---|---|---|---|
| PM12 | 110 | 100 | 10 | 300 | 32–39 | 6.0 |
| PM16 | 160 | 130 | 10 | 240 | 43–52 | 8.2 |
| PM24 | 240 | 200 | 10 | 300 | 43–52 | 10.6 |
The minimum breaking loads of 110 kN, 160 kN, and 240 kN for PM12, PM16, and PM24 respectively ensure that the bolts can withstand substantial tensile forces, while the minimum yield loads (100 kN, 130 kN, 200 kN) guarantee controlled deformation under loading. A 10 % minimum elongation (A100mm) across all models provides the ductility needed to absorb rock movements without sudden failure—a critical feature in dynamic mining environments.
Inflation is achieved with water pressures of 300 bar for PM12/PM24 and 240 bar for PM16, which forces the tube profile to expand and lock against the borehole. The required hole diameters (32–39 mm for PM12, 43–52 mm for PM16 and PM24) accommodate standard drilling equipment, while the profile diameters (27 mm for PM12, 36 mm for the larger models) and tube thicknesses (2 mm for PM12/PM16, 3 mm for PM24) are optimized for strength and weight. A single 50 cm inflated section can generate 100 kN of friction, illustrating the exceptional anchorage capacity that develops along the entire bolt length.
Weights range from just 2.50 kg for a 1.2 m PM12 bolt up to 23.10 kg for a 6 m PM24, enabling easy handling while delivering massive support. This combination of high strength and light weight reduces installation fatigue and boosts productivity underground.
The SupHulk bolt’s steel profile is designed to accommodate shear movements without failure, making it suitable for medium to soft rocks where conventional grouted bolts may crack. The bolt can also bridge small gaps in the rock mass, and the optional SupHulk net washer allows for effective screening of loose material, adding another layer of safety.
SupHulk friction rock bolts have proven their worth in some of the world’s most demanding underground environments. In tunneling, they are used as pattern bolts to support excavations in varying rock masses, with spacing patterns tailored to the excavation dimensions and rock mass quality. Whether in soft sedimentary rocks or highly fractured metamorphic terrains, the immediate friction anchorage provides rapid stabilization, allowing tunnel boring machines and drilling rigs to advance without delays.
In mining, common applications include roof bolting and hanging wall bolting, where the bolts must quickly secure potentially unstable ground above and beside the working area. The ability to bear full load immediately after installation means that mining crews can work under a secure roof minutes after bolting, dramatically improving cycle times.
Features that make SupHulk bolts the preferred choice include:
The system’s simplicity also shines in emergency situations: after a rock burst or seismic event, additional bolts can be rapidly installed to reinforce compromised areas, with no curing time required.
The global demand for reliable ground reinforcement solutions continues to rise as infrastructure projects push into more challenging geological settings. From high‑speed rail tunnels in the Alps to deep‑level gold mines in South Africa, engineers require bolts that can handle high stress, water ingress, and dynamic loads. The SupHulk PM series, with its three capacity tiers, fits neatly into a broad range of self‑drilling anchor bolt and geotechnical reinforcement system portfolios, offering an alternative to traditional resin‑ or cement‑grouted bolts.
While hollow bar anchors and drill‑and‑grout bolts remain dominant in many regions, friction bolts are gaining market share due to their speed and immediate support. In projects where ground conditions are too unstable for grout to set properly, or where water inflows wash away cement, SupHulk bolts provide a fail‑safe solution. The global hollow bar anchor market is projected to grow at a steady pace, and SupAnchor’s innovation positions it as a key factory and manufacturer for clients seeking ground anchor bolt systems that combine performance with cost efficiency.
SupAnchor’s self‑drilling anchor systems are already well established in Europe, the Americas, and Australia, where adherence to strict safety standards is non‑negotiable. The PM series bolts meet or exceed EN and other international standards, ensuring seamless integration into any project specification. As a soil nail system manufacturer and ground anchor bolt factory, SupAnchor leverages its vertically integrated production to offer competitive pricing without compromising quality.
Behind the SupHulk brand is SupAnchor, a company with decades of experience in geotechnical anchoring. With ISO‑certified manufacturing facilities and a dedicated R&D team, SupAnchor continuously refines its products to meet evolving field demands. The friction rock bolt system is just one element of a comprehensive lineup of self‑drilling hollow bars, soil nails, and anchorage accessories that serve mining, tunneling, and slope stabilization projects worldwide.
The company’s collaborative approach means that engineers and contractors receive not only the bolts but also the technical support, installation training, and inflation equipment needed to maximize performance. This partnership model has earned SupAnchor a reputation as a professional and reliable supplier in over 50 countries.
As the industry moves toward more mechanized and safer underground practices, the SupHulk friction rock bolt stands out as an innovation that combines simplicity with robust engineering—exactly what the market needs for the next generation of geotechnical challenges.
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