Split set stabilizers, also known as friction bolts, are a popular form of rock support in underground mining operations. They provide immediate support to rock formations in tunnels, shafts, and other excavations, which helps prevent rock falls and ensures the stability of mine structures. Split sets are made from high-tensile steel tubes with a slot down the entire length, and they work by creating friction between the rock surface and the bolt. Here’s a closer look at how they’re used and the advantages they offer.

The typical split set stabilizer consists of a long, slotted steel tube, which has a diameter slightly larger than the drilled hole in the rock. The tube is driven into a hole, compressing as it fits tightly against the rock surface. This compression generates friction, which anchors the stabilizer securely. The bolt’s length and diameter depend on the specific geological conditions and load requirements. A bearing plate is placed at the end of the split set, which holds up rock pieces that might otherwise break off or collapse.

The friction between the rock and the steel bolt creates a self-locking mechanism, making the split set an effective stabilizer. Unlike traditional bolting systems that require resins, grout, or other mechanical fasteners, split sets rely purely on friction. This simplicity allows for faster installation, an essential feature in active mining operations where time is of the essence.

Installing a split set stabilizer involves drilling a hole into the rock, typically with a diameter slightly smaller than the bolt. Once the hole is drilled, the split set is inserted using a bolting machine, which pushes the bolt into place until the bearing plate is flush with the rock face. This process is relatively quick and doesn’t require additional materials or curing time, which can slow down operations.

The installation is also reversible if adjustments need to be made, which is helpful in areas where geological conditions may change, or if the support needs to be reoriented. Additionally, split sets can be used in conjunction with mesh or other reinforcement systems for added stability.

Ease and Speed of Installation: Split sets can be installed rapidly without the need for complex tools or materials, making them ideal for time-sensitive mining operations.

Immediate Support: Because split sets work on friction alone, they provide instant support. This quality is critical in high-risk areas where immediate reinforcement is necessary to prevent rock falls.

Flexibility and Adaptability: Split set stabilizers are compatible with various other support systems, including mesh, shotcrete, and other rock bolts. They can be combined with these systems to create a comprehensive and highly secure support structure.

Reduced Need for Resins or Grout: Many other rock bolts require chemical adhesives or mechanical anchoring systems. Split sets eliminate the need for these materials, simplifying installation and reducing potential exposure to harmful chemicals.

Cost-Effectiveness: Split sets are relatively inexpensive to produce and install. Their durability, ease of installation, and elimination of additional materials like resins contribute to long-term savings for mining companies.

Split set stabilizers are used in various mining environments, including:

Tunnels and Shafts: To stabilize the walls and roof in tunnels and vertical shafts.

Backfilling Operations: For providing temporary support until backfill materials, such as cemented paste or waste rock, are in place.

Longwall Mining: In longwall mining operations, split sets are used to stabilize entryways and prevent rock shifts as the longwall advances.

High-Stress Conditions: In conditions where the rock is highly fractured, split sets provide reliable support that adapts well to rock movement and deformation.

Limitations and Challenges

Despite their advantages, split set stabilizers also have some limitations. Over time, they may corrode in environments with high moisture or corrosive minerals, which can reduce their effectiveness. To address this issue, coated or galvanized split sets are sometimes used, though these are more expensive. Additionally, split sets may not provide the same level of support as some grouted bolts, especially in very soft or fractured rock conditions, where more substantial reinforcement might be necessary.

The ongoing development in split set technology has led to variations that address common challenges like corrosion and load-bearing capacity. Some modern split sets come with coatings that resist corrosion, making them more suitable for damp or corrosive environments. Others feature reinforced steel or hybrid materials for additional strength.

Split set stabilizers are an essential tool in the mining industry, providing quick, reliable support to enhance the safety of underground operations. Their simplicity, ease of installation, and adaptability make them ideal for challenging mining environments, where rapid, effective support is necessary. While they may have some limitations, ongoing innovations in materials and design continue to expand their applicability, ensuring that they remain a preferred choice for mine support worldwide.