Swellex rock bolts are widely used in mining to stabilize rock masses in underground excavations, providing safety and preventing roof falls or collapses. These hydraulically expanded bolts, developed by Epiroc, are effective due to their simplicity, rapid installation, and adaptability to various ground conditions. Below is a step-by-step guide on how to use Swellex rock bolts for mine support, tailored to a 500-word explanation.

Step 1: Assess Ground Conditions and Design Support Plan

Before installing Swellex rock bolts, evaluate the geological conditions of the mine, including rock type, stress levels, and potential for deformation. Swellex bolts are versatile, suitable for hard rock, soft rock, or seismically active environments. Determine the required bolt length (typically 1.5–3 meters) and diameter (20–40 mm) based on the excavation size and load requirements. For high-stress environments, consider Swellex Premium (Pm) or Manganese (Mn) lines, which offer high yield loads and energy absorption for dynamic conditions like rock bursts. The bolting density depends on the rock mass’s self-supporting capacity and excavation dimensions, often used for roof or hanging wall support.

Step 2: Drill the Borehole

Drill a borehole into the rock mass using specialized drilling equipment. The borehole diameter should be slightly smaller than the folded Swellex bolt’s circumference, typically 0.9–0.95 times the bolt diameter in rock layers or 0.9–1.0 times in coal seams. For example, a 28 mm Swellex Pm12 bolt requires a borehole of about 25–27 mm. The drilling depth should be the bolt length plus 100 mm for rock or 200 mm for coal, with a deviation rate below 1–1.5%. Clear the hole of debris using compressed air to ensure proper bolt insertion.

Step 3: Insert the Swellex Bolt

The Swellex bolt is a welded steel tube, folded on itself, sealed at one end, and equipped with a head bushing for inflation. Insert the bolt into the drilled borehole manually or using a bolting rig. Ensure the bolt is fully inserted, with the head bushing accessible for connection to the expansion pump. A face plate is typically attached to the bushing to provide local surface support around the borehole collar, transferring rock mass displacement to the bolt.

Step 4: Expand the Bolt

Connect the bolt’s head bushing to a high-pressure water pump, such as the Epiroc HC1-L or EC1-L, which delivers 240–300 bars of pressure. Inject high-pressure water to expand the bolt, causing it to deform permanently and conform to the borehole’s irregular shape. This creates friction and interlocking along the entire length, providing full-column support. The pump maintains pressure for a set period to ensure proper expansion, and installation parameters are logged for quality control. Once expanded, the bolt releases internal pressure, securing it in place.

Step 5: Verify Installation and Monitor

After expansion, check that the bolt is securely anchored and the face plate is flush against the rock surface. Swellex bolts are not sensitive to hole diameter, rock quality, or water conditions, making them reliable in diverse settings. For long-term durability, use corrosion-resistant variants with zinc or epoxy coatings, especially in humid or chemically harsh environments. Regular monitoring, using devices to detect ground movement, ensures ongoing stability.

Applications and Benefits

Swellex bolts are ideal for roof bolting, hanging wall support, or stabilizing tunnel perimeters. Their quick installation, requiring no grout or resin, reduces labor and time costs. They adapt to shear movements and provide high load capacities (120–240 kN), enhancing safety and productivity.

By following these steps, Swellex rock bolts provide a robust, efficient solution for mine support, ensuring worker safety and operational efficiency.