Friction bolts (Split sets)
Friction Bolts (Split Sets)
Product Description
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Product Description
The friction bolts (split sets) are constructed from high tensile (SUPRAFORM MC 420 or equivalent) high-grade steel. This material is roll-formed into a tubular section with a continuous longitudinal opening along the tube.
An 8mm steel ring paired with a 47mm diameter split set is fixed at the collar end (5mm from the edge) of the tube. When the split set is installed into the recommended drilled hole size along with the desired bearing plate, it generates a compressive force against the rock. The tapered end of the friction stabilizer allows for easy insertion into the drilled hole. The compression of the tubular shape of the split set into the smaller diameter hole ensures load transfer from the steel to the rock.
The tubular shape of the bolt increases the contact between the steel and rock, producing radial pressure and creating frictional resistance to prevent the tube from pulling out of the hole.
Nominal sizes: 33mm, 39mm, 46mm, and 47mm diameter
Dimensions:
| Type | SS33 | SS39 | SS46 |
|---|---|---|---|
| Outer Dia (mm) | 33 | 39 | 46 |
| Wall Thickness (mm) | 2-2.5 | 2-2.5 | 2.5-3.0 |
| Weight (kg/m) | 1.68 | 1.96 | 2.8 |
| Bearing Plate (mm) | 150 x 150 x 4 | 150 x 150 x 4 | 150 x 150 x 4 |
| Borehole Dia (mm) | 30-32 | 36-38 | 43-45 |
| Bolt Length (m) | 0.9-2.4 | 0.9-3.0 | 0.9-3.7 |
| Min Yield Strength (kN) | 80 | 90 | 120 |
| Min Tensile Strength (kN) | 100 | 115 | 165 |
| Elongation | ≥16% | ≥16% | ≥16% |
| Typical Anchorage (kN min.) | 20 | 20 | 20 |
* Black or hot dip galvanized split sets are available to meet various mining environmental conditions.
Package and delivery:
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Working Principle of Split Set
Over recent decades, the complexity of geological environments in mining and tunnel construction has increased. Traditional rock bolt technology often fails to address the reinforcement issues of surrounding rock, prompting engineers to seek new solutions. The split set emerged as a solution, quickly gaining recognition from engineers due to its unique design and excellent performance.
Structure of the Split Set
Split set is a novel anchor for full-length anchoring and active reinforcement of surrounding rock. It is widely used globally and primarily consists of a high-strength anchor rod and a tray. The anchor rod has longitudinal slits, enabling it to adapt better to the shape and size of the surrounding rock. Once embedded in the borehole, these gaps generate friction, applying internal radial pressure on the rock. Additionally, the anchor tray prevents rock sliding and provides extra support.
Working Principle of Split Set
The split set is a high-strength anchor rod featuring longitudinal slits. When placed in a borehole slightly smaller than the pipe diameter, it exerts radial pressure along the entire length of the hole and prevents rock sliding, supported by the anchor tray. This three-directional stress state stabilizes the rock stratum. In cases of blasting vibration or rock movement, anchoring force increases significantly, and the rock bolt maintains its support resistance even with substantial rock displacement.
Characteristics of Split Set
Swift Installation: Installation is efficiently completed using impaction, eliminating the need for anchoring additions, thereby ensuring quick anchor formation.
Immediate Bearing Capacity: The split set generates friction with surrounding rocks, providing immediate bearing capacity post-installation.
Ease of Handling and Installation: The hollow, thin-walled, lightweight rod is easy to transport, carry, and install manually.
High Performance: High friction between the anchor rod and rock mass ensures high shear and tensile strength. The drilling depth exceeds the depth of the rock bolt, offering timely radial and axial support. It is unsuitable for permanent support in soft rock.
Economic Efficiency: Utilizing split set support reduces material input and direct support costs.
Processing Technology of Split Set
The production process involves hot-rolled steel strip molding, cutting to length, welding retaining rings, surface cleaning, electro-galvanizing or hot-dip galvanizing, and packaging/storage.
The advent of split sets has revolutionized the understanding of geotechnical reinforcement, offering new methods for addressing complex geological conditions in engineering projects. Now playing a crucial role in mining projects, further advancements in split set technology and design could enhance its application in geotechnical engineering, providing robust support for project construction.
Are you interested in learning more about Split Set Mining Systems? Contact us today to secure an expert consultation!
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