Abstract: This article introduces the surrounding rock control technology of the 1022 machine tunnel joint tunnel coal hole in Yuandian No. 1 Mine, including temporary support and permanent support technology, and puts forward the construction quality requirements. The engineering construction effect is good. . Keywords: Coal hole surrounding rock control technology anchor bolt
CLC number: TD82 Document identification code: A Article number: 1672-3791(2012)05(a)-0075-01
The coordinates of the eye of the 1022 machine lane joint coal eye are: 5183mm. The design adopts anchor rods and steel mesh support, and concrete permanent support is poured after the support is completed.
1 Temporary support
(1) After blasting from bottom to top, 2 capped point pillars are used as temporary supports. The point pillars must be installed in time, otherwise they cannot be installed in the actual Square wood or sleepers should be placed on the bottom.
(2) When constructing from top to bottom, construction workers must wear safety belts.
(3) After temporarily supporting the roof, remove the anchor rods at the side of the coal hole, and the metal mesh supporting the coal hole anchor net is welded with Φ6mm ribbed steel bars, with a specification of 2100×900mm. The grid is 100×100mm, the hooks and loops are connected, and every loop must be hung. The specification of the anchor rod is φ20×1800mm. Each anchor rod is anchored with 2 rolls of K2950 resin anchoring agent. Because the cross-section of the coal hole is small, the hollow construction method is used when constructing the anchor hole.
After the anchor support of the upper part is completed, it should be sealed with shotcrete in time.
2 Construction technology
2.1 Anchor installation technology
2.1.1 Drilling the anchor eye
Before drilling, strictly follow the center line Check the cross-section size. Before drilling, you must first clean up the gravel in the eye, remove live gangue and dangerous rocks, and only start work after confirming safety. The position of the anchor eye must be accurate, and the eye position error must not exceed 100mm. The eye direction The error shall not be greater than 15°. The depth of the anchor should match the length of the anchor. When drilling, the drill should be marked and drilled strictly according to the length of the anchor. Clean the anchor hole after drilling.
2.1.2 Installing the anchor
Before installation, use compressed air to blow away the accumulated water and rock powder in the eyelet. Send two rolls of resin anchoring agent into the fundus, insert the anchor rod into the anchor hole, make the anchor rod resist the resin anchoring agent, put a nut on the outer end, use an anchor drill with a special sleeve to clamp the nut, and start The anchor drilling rig drives the rod body to rotate, screws the anchor rod into the resin anchoring agent, and stirs until the anchor rod reaches the design depth and the rotation and stirring time is greater than 5s to 10s. The anchor rod drilling rig can be removed. After 12 minutes, tighten the nut to the anchor rod. Apply a certain preload force.
2.2 Shotcrete process
2.2.1 Preparation
(1) Check whether the anchor installation and reinforcement mesh laying meet the design requirements.
(2) Clean up the gangue and debris at the injection site and connect the feng shui pipeline.
(3) Check the shotcrete machine, power on and run without load, and tighten the friction plate.
(4) The rock surface must be flushed with high-pressure feng shui before spraying.
(5) Spray personnel should wear complete and effective labor protection supplies.
2.2.2 Shotcrete process requirements
The spraying sequence is: the coal hole is moved from bottom to top, and the spray gun head and the sprayed surface should be kept vertical as much as possible. The cement, sand and gravel should be cleaned and stirred three times to make them evenly mixed. During the spraying process, the water supply volume is adjusted according to the change in the discharge volume, so that the concrete has no dry spots, no flow, and little rebound.
2.2.3 Spraying work
Before starting the spraying work, first lay a thin iron sheet at the spraying location to collect the rebound material. After the spraying work is completed, the nozzle must be removed immediately and cleaned. Water ring and gunite for all interior and exterior grouts and materials. Sprinkle water in three shifts within 7 days for maintenance, and sprinkle water once a day after 7 days. When starting up, you must first supply water, then turn on the air, then turn on the machine, and finally load the material; when shutting down, you must first stop the material, then stop the machine, then turn off the water, and finally stop the air.
2.3 Locking beam construction technology
(1) After the anchor shotcrete support construction is completed, dig out the beam nest position at the lower entrance of the coal hole according to the designed position, and the length of the locking beam The beams are all made of ordinary hot-rolled I-beam 32b#. There are 2 long I-beams, each 4800mm long; 2 short I-beams, each 820mm long. The long and short I-beams are connected using 20# angle steel and fully threaded bolts M20×80. The angle steel is 8mm thick. There are φ22mm circular holes and 4 φ22 preset bolt holes in the middle of the 6mm thick steel plate. Use fully threaded bolts M20×50 to connect to the lock beam. The φ18mm hole is set in the middle of the long I-beam web.
(2) Reinforcement beams, one to three pairs, each pair is composed of two U-shaped steels, each length is 4175mm, 6 pieces, processed into an arc shape with an outer diameter of 1262mm, Process φ22mm round holes at intervals of 700mm on the upper side.
(3) Two U-shaped steel butts form a pair of circular reinforced beams. The two joints are reinforced with a pair of clamping cables. The upper and lower pairs of clamping cables are connected with tie rods to form a whole body. .
(4) Drill four lifting anchors at the top of the tunnel, use inverted chains to pull the locking beam to the designed position and level it. Put the two long I-beams into the beam nests. After they are connected, lift the short I-beam and the long I-beam to connect them, and then lift the 6mm thick steel plate to assemble and connect them.
2.4 Concrete pouring process
2.4.1 Formwork assembly
12# channel steel is used to make the arch support formwork, and the arch is made of two butt-jointed pieces. , the net radius of the arch is 1000mm, and the tie rods made of φ20 rebar are used to connect the arches. After the arch is leveled and aligned, the upper part of the arch is supported on the alley with square wood, and the arch is reinforced firmly. Then start placing the formwork and tie the formwork together with iron wire so that the formwork is close to the arch. Once the mold is erected, pour the mold in time, and then erect the formwork upwards after the pouring is completed.
2.4.2 Concrete pouring
The strength of the concrete poured into the coal hole is C30, the wall thickness of the coal penetration section is 500mm, and the wall thickness of the rock section is 300mm, using a bottom-up one-time method. For pouring, the concrete weight ratio is: cement:yellow sand:gravel=1:2.05:3.5, the water-cement ratio is 0.51; the materials must be mixed in advance, vibrated while pouring, and the underground water supply pipeline provides water. Concrete preparation is done manually on site. When pouring, stir at the top of the coal hole.
Arrange special personnel to observe the formwork during pouring, and deal with any movement in a timely manner. When pouring concrete, pour it into the mold vertically, cut the material evenly, and pour it symmetrically and continuously in layers. The vibration work requires designated people and fixed points to vibrate in layers, and vibrate along with the pouring.
3. Construction quality requirements
(1) When drilling, construction should be carried out in strict accordance with the blasting chart, and strict implementation of one package (charter), two determinations (determination of people, positioning), and one insistence ( Adhere to the system of wet rock drilling) and five no-nos (no construction without measures, no marking without blasting charts, no drilling without marking, no drilling without drilling, and no charging if the drilling quality is not up to standard). The blast holes must be accurate, flat, straight and aligned, and the blasting and support parameters shall be adjusted according to the changes in the lithology of the working face.
(2) The allowable deviation of the spacing of anchor rods is ±100mm, the depth of the anchor rod hole is 0~+50mm, the length of the exposed anchor rod pallet is 10mm~40mm, and the nuts must be tightened. Anchor rods must be arranged vertically on the roadway or rock face, and the allowable deviation is ≤15°. Empty roof operations are strictly prohibited. If the anchor rods are enough for one row, drill one row.
(3) Before installing the anchor rod, check the quality of the anchor rod eye and check whether the anchoring agent is intact.
(4) When drilling anchor rods, use a φ28mm straight-edge drill bit. The material, variety, specifications, strength, and structure of the anchor rod body and accessories must meet the requirements.
(5) The installation of the anchor rod must be firm, with the supporting plate close to the rock surface; the anchor rod torque is not less than 300N·m, and the pullout resistance is ≥80kN.
(6) The welding, laying and hooking of metal mesh must comply with the design and specifications. The hooks and loops are connected and cover the entire coal hole wall.
(7) Before installing the anchor rod, pressurized air must be used to blow away the rock powder and debris in the eye to ensure the quality of the anchor rod installation. All failed anchors must be replaced.
(8) The thickness of the shotcrete must meet the design requirements. The under-excavated part must be treated adequately, and the over-excavated part must be poured and filled with concrete.
(9) The concrete must be stirred evenly, and vibrated compactly with a vibrator after pouring. There should be no obvious cracks on the concrete support surface.
(10) The deviation from the center line to the center of the coal hole is 0~ +50mm.