What is the process of mining rock bolt installation?

　　Drilling is a crucial step in controlling the construction schedule of mining rock bolts. To ensure drilling efficiency and quality, a DTH impact drill is used. During drilling, according to the design length of the anchor chain, the required drill bits are placed neatly. After using the drill bits, the hole depth is accurately placed in its original position. The drilling depth should exceed the design length of the rock bolt by about 0.5 meters.

　　After drilling, the drill rods and drill bits are removed one by one, the impactor is thoroughly rinsed, and preparations are made. The hole depth is checked using a polyethylene pipe, and high-pressure air is used to blow out the hole until the dust inside the hole is blown clean. If the hole depth is less than the design length of the rock bolt, the polyethylene pipe is pulled to plug the hole.

　　Handling of two special situations in mining rock bolt installation:

　　Water leakage handling. During drilling or when blowing the hole after drilling, if small stones and gray or yellow blocky substances are blown out from the hole, it indicates water seepage inside the hole, with rock powder adhering to the hole wall. In this case, if the hole is deep enough, clean water is injected and blown clean until clean water is blown out by high-pressure air. If the hole is not deep enough and particles are still present when the impactor is working, drilling should be stopped immediately, the drill bit removed, the hole rinsed, and drilling continued. This cycle is repeated until the mining rock bolt reaches the required depth. If there is a large amount of water seepage in the hole, with accumulated water, mud, and stones being blown out, in this case, the rock powder does not coat the hole wall, and as long as the impactor is functioning, drilling can continue. If too much water seeps in and the impactor is submerged, the impactor will automatically stop working, and the drill bit needs to be removed for pressure grouting.

　　Collapsed hole and drill bit jamming handling. When drilling through strongly weathered rock layers or fractured rock masses, collapsed holes often occur. The main sign of a collapsed hole is the blowing out of yellow rock powder mixed with original (in situ, unweathered, lusterless) rock fragments from the hole. In this case, regardless of the drilling depth, drilling should be stopped immediately, the drill bit removed, and hard wall grouting performed. The grouting pressure is 0.4 MPa, and the grout is a mixture of cement mortar and water glass. During the rainy season, mud often penetrates into the hole along the rock fragments, and the mud should be rinsed with water and air before compacting the walls.

　　Mining rock bolts are assembled on-site during drilling. The internal anchoring section uses a corrugated shape, and the tension section uses a straight shape. The steel wire length is the sum of the design length of the rock bolt, anchoring height, jack length, tool anchor rod and working anchor rod thickness, and stretching working balance. Generally, the steel strand cutting allowance is 50 mm. The cut steel strands are placed steadily on the workbench, and the internal anchoring section and the design length of the rock bolt are measured and marked separately. At intervals of 60-100 cm, fixing rings are tied between two pairs of intermediate supports, and the intermediate isolation supports are penetrated within the internal anchor section. (Note: At intervals of 60-100 cm, fixing rings are tied between two pairs of intermediate supports.) A fixing ring is tied every meter in the tension section, and the caps are strung together with plastic tubes and coated with grease. Then, the guide cap is placed on the end cap of the rock bolt.