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Construction technology and application of FRP bolt in coal mine

Release time:

2023/12/01 17:30

As an effective way to support roadway, bolt support can not only significantly improve the effect of roadway support, but also enhance the stability of surrounding rock. It can also save a lot of support and maintenance costs, and has the advantages of low support cost, fast roadway formation, and low labor intensity. Therefore, bolt support has become a main support method for mine roadway support, and is widely used. be applied. Anchor bolt support is a hidden project. Once there is a problem with the construction quality, and it is easy to cause a roof fall accident, for this reason, on-site construction becomes the key link of bolt support. Operators must understand, be familiar with and master the construction technology of bolt support.

1 Structural characteristics of resin anchor

Resin anchor rod consists of rod body, anchoring agent, tray and nut. The resin bolt is simple to operate, easy to install, and has the advantages of fast anchoring speed, high strength, easy to change the anchoring method, easy quality control, safety and reliability.

2 Installation process of resin bolt

2.1 The storage and use of resin anchoring agent should comply with regulations

1) Resin anchoring agent should be stored in a dark and fireproof warehouse at 4-25℃.

2) The properties of the resin anchoring agent should be checked before the bolt is installed. It is strictly forbidden to use the anchoring agent that has deteriorated and failed such as expired, induration, cracking, etc.

3) For underground transportation and storage of resin anchoring agent, care should be taken to avoid being compressed, folded, heated, damaged or discarded.

4) When stirring the resin anchoring agent, the stirring time and waiting time must be strictly controlled according to the following standards: It is recommended to use two kinds of resin anchoring agents: fast and medium speed. Install the fast and medium-speed first, and send the resin anchoring agent to the hole with an anchor rod. At the back of the bottom, stir while advancing, stop stirring for 20 to 30 seconds, wait for 2 minutes, and then drop the drilling rig.

5) When installing the resin anchoring agent, the anchoring agent must be placed in the bolt hole in strict accordance with the order and quantity required by the design.

2.2 Requirements to be followed when installing resin bolts

1) It is advisable to adopt a quick installation process, that is, stirring the resin coil, placing the pallet, and screwing the nut at one time.

2) It is advisable to use a bolting rig as an installation tool.

3) The installation torque should be controlled at 30-40N.m to prevent the rod body from being twisted.

4) The support plate at the end of the anchor rod should be close to the joist or wall, and the non-contact parts must be tightly packed.

5) The distance between the nut and the tail end of the anchor rod body shall not be greater than 50mm. The row spacing between the anchor rods shall not exceed the design value +50mm.

2.3 Installation steps of resin bolt in coal roadway

2.3.1 Drilling holes

Use a coal electric drill with a twist drill pipe and a bi-wing coal drill bit matched with the anchor rod to drill the hole, and the hole depth is controlled within the specified range.

Anchor eye angle and hole depth. The bolt arrangement direction should be as vertical as possible to the roadway outline (or the main bedding plane of the rock stratum), and the included angle should not be less than 75°. The depth of the bolt eye must match the length of the bolt, and the error of the eye depth is 0~+30mm, which shall be specified in the operation regulations.

2.3.2 Charge roll

Before installation, all bolt holes should be swept with compressed air to remove accumulated water and slag. Check the quality of the bolt hole (depth and angle), whether the bolt components are complete, and whether the to-be-charged coil is hardened, expired or damaged (it is strictly prohibited to use hardened, expired or damaged coils), and resin The type and quantity of the medicine rolls are sequentially loaded into the holes.

The hole diameter of the bolt should be reasonably matched with the straight diameter of the bolt and the diameter of the resin coil. The annular wall thickness of the anchoring agent should be controlled within 4-10mm. When the aperture allows, the large diameter resin roll should be used as much as possible.

2.3.3 Insert the bolt body

The bolt body is covered with a support plate and a nut, the end of the rod is connected with the bolt head through a connecting sleeve, the rod end is inserted into the rock hole with the resin coil installed, the bolt machine is raised and the hole is fixed by the bolt body. The medicine roll at the mouth is pushed into the hole, so that the medicine roll contacts the bottom of the coal hole, and then the rock bolt machine starts to stir the medicine roll.

After the resin anchoring agent has solidified for 1 hour, the tensioning and pre-tightening of the upper pallet can be carried out. The pre-tightening force is generally not more than 60KN for φ18, not more than 70KN for φ20, and not more than 80KN for φ22.

2.3.4 Installing the tray and nuts

It is necessary to use a rock bolt drilling machine or other special bolt installation equipment to fully stir and mix the resin anchoring agent. And use the quick installation process, that is, stirring the resin anchoring agent, placing the tray, and tightening the nut at one time. It is strictly forbidden to install the anchor rod by means of hammering or wind hammer stirring.

The installation torque of the coal roadway anchor rod should be controlled at 30-40N.m to prevent the rod body from being twisted, and the anchoring force should not be greater than 60 kN.

After the bolt is installed, the tray should be close to the coal wall. The nuts must be tightened with a pneumatic wrench or torque wrench, and all anchors should be tightened twice in time to ensure that the tightening torque of the anchor nuts meets the design requirements.

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