Safety technical measures for the construction of

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Technical safety measures for the construction of the central air return crosscut refuge chamber

I. construction overview:

due to the high cost of the central air return crosscut refuge chamber is located 17930 ㎜ (middle) south and east of the central air return crosscut L02 intersection. The main purpose is to facilitate the shelter of construction personnel in accordance with the requirements of the four in one comprehensive outburst prevention measures, when there is a sound or silent outburst sign in the blasting or coal seam

the chamber belongs to rock roadway construction. The excavation section is B (excavation) *h (excavation) =3240*2620 mm, s excavation =7.36m2; The net section is B (net) "these parts can be operated for injection molding once * H (net) = 3000*2500 mm, s net =7.125m2. The waist line is 1000 mm from the roadway floor. The work quantity is 4500mm. The roadway is supported by bolting and shotcreting, and the shotcreting thickness is 120 mm

II. Preparations before construction

the construction site mainly includes cables and air ducts, opposite which is the Feng Shui pipeline. Before construction, put the cable within 30 meters before and after the construction site into the ditch and cover it with a large plate. At the same time, hang the air duct at the door, and cover the air and water pipelines with a large plate to avoid being destroyed by blasting

III. construction method

the construction method of manual drilling, blasting and tunneling, manual shipment, 1.5-ton fixed Tramcar Transportation, parallel and cross operation of multiple processes, and one-time roadway formation is adopted

construction process: safety inspection, drilling and blasting, safety inspection, temporary support, delivery, roof bolting, and side bolting

IV. support method and support quality requirements

1. For advanced and temporary support, use capped point posts as temporary support

2. When the permanent support method of bolting and shotcreting is adopted in this project, the anchor rod shall be selected Ф 20 mm metal equal strength anchor bolt, l=2200 mm, the row spacing between anchor bolts is 800*800 mm, and the anchoring length is 1300 mm. One roll of k2335 and three rolls of z2335 resin anchoring agent are used for the drug coil, and the anchoring force is not less than 7 tons. The metal is Ф 6mm @100*100 mm, the pressing plate is 120*120*10 mm metal steel plate, the shotcrete thickness is 120 mm, and the concrete strength grade is C20

3. Quality requirements for permanent support

(1) the anchor rod shall be close to the metal and rock surface, the row spacing shall be 800 mm, the error shall not exceed 100mm, the angle between the anchor rod direction and the shaft and roadway contour line shall not be less than 75, the anchor rod shall be less than 50mm above the tray, and the torque of the tray nut installation must be more than 100n*m. The initial shotcrete must be more than 30mm

(2). Anchor bolt tension: the anchoring force of top and side anchor bolts shall not be less than 7T

(3). The metal lap length is 100 mm, with an interval of 300 mm. If this phenomenon occurs again, unscrew the outer 6-corner screw on the end face of the oil pump and connect it with 2

(4) the metal must be close to the rock surface. In case of local roof falling, the roof must be supported by shotcreting first, and then close to the roof falling part. The supporting bolt shall be punched according to the design requirements for support, and the roof falling part shall be shaped according to the requirements of the net size of the roadway, so that the roadway as a whole meets the design requirements

(5) the mix proportion of shotcrete material is 425 × ordinary silica cement: medium coarse sand: Stone (particle size 5 ~ 15mm) =1:2:2, which is proportioned on the ground; Before or after shotcreting, the rock surface of the roadway must be thoroughly flushed, and the thickness of shotcreting must be guaranteed. After shotcreting, the watering and maintenance of the roadway behind the construction must be insisted on every day. The shotcreting part shall be watered not less than 1 ~ 2 times per shift, and the watering shall be insisted on not less than 14 days. The specification deviation of shotcrete support roadway: the distance deviation from the roadway centerline to any side is 0~+150; The distance deviation from the waist line to the top and bottom plate is 0~+150

Government subsidies

(6) and temporary support followed

v. safety measures

(I) roof management measures

1 During construction, the system of knocking on the side and asking for the top must be adhered to. Find and clean the dangerous rock floating gangue on the top and side at any time. During operation, use a drill rod or long handle tool with a length of not less than 1.5 meters to knock the top from the outside to the inside and from the top to the top. When finding the top, there should be a special person to monitor the top to ensure safety

2. During anchor support, the roof bolts must be installed row by row from the outside to the inside. The included angle between the anchor rod and the surrounding rock shall be no less than 75, and it shall not be arranged along the crack surface, and it is not allowed to penetrate the skin

3. Strengthen roof management, prohibit empty roof operation, and strictly prevent roof falling accidents. In case of roof fall due to faults, structures and other reasons, the roof must be filled with incombustible materials after the roof is stable or leaks into a pointed shape. Materials must be prepared and the retreat road must be cleared before the roof connection. At the same time, the gas concentration in the roof falling area must be monitored. When the concentration exceeds 0.8%, it is strictly forbidden for personnel to go up to the roof for operation. When ventilation dilution is adopted and the concentration drops below 0.8%, a special person should be assigned to monitor the roof during roof connection. The team leader watches the shift on site. The position and height of the roof fall area shall be marked after the roadway is formed in the roof fall area

4. If the roof is pulled out in front of the structure, the wedge striking method can be used to strengthen the roof in advance to prevent the roof from falling out. The reinforcement method: use a 1.5-meter-long log or 2-inch steel pipe to wedge from the first overhead shed to the top of the first overhead shed beam, one at an interval of 0.3 meters, wedge 0.8 meters in advance, and fully control the roof to prevent falling

(II). Blasting and initiating explosive device management measures

1 It is strictly prohibited to continue drilling in the residual blast hole. It is strictly prohibited to drill holes and charge in parallel

2. Strictly implement the system of one shot, three inspections and three person chain firing. Full time blasters and gas inspectors shall be set during construction

3. Before charging, the eye must be swept with compressed air. During charging, the roll of medicine must be pushed gently with a gun stick, and it is not allowed to collide or tamp

4. Millisecond delay electric detonators must be used during shooting, and the last delay time of electric detonators shall not exceed 130ms. It is strictly forbidden to skip the section. The permissible three-level water containing explosive used in coal mine shall be used. And the forward charging blasting construction is adopted

5. The gunshot hole shall be sealed with water gunshot mud and clay gunshot mud. It is strictly forbidden to blast without blasting mud and replace blasting mud with water blasting mud. The sealing length of blast holes must be strictly in accordance with Article 329 of the coal mine safety regulations

6. Before blasting, the head-on tools and equipment shall be removed and covered up. The blasting bus and connecting wire, electric detonator pin and connecting wire, and the joints between pin and pin must be tightened with each other and hung away from the live conductor. Watering and dust removal must be carried out in the roadway 30 meters from the front to the back. After blasting, take the probe to the design position and hang it

7. Special shooting cables shall be used for shooting. The blasting cable, power cable, wire and signal wire should be hung on the two sides of the roadway respectively. If they must be hung on the same side, the blasting cable must be hung below the power cable and a distance of more than 0.3m should be maintained

8. During blasting, the blasting site is set in the refuge chamber, and the distance from the refuge chamber to the head shall not be less than 100 meters. The watchman must be personally sent by the team leader and the team leader. He cannot withdraw without being informed by the team leader. Warning signs, railings or ropes shall be set at the warning place. There are mainly three shooting warning positions: 80 meters north of No. L02 intersection; No. 13 intersection of the parking lot at the bottom of the air return shaft; One at each crossing point L01

9. After blasting, after the blasting smoke is discharged, the gas inspector, blaster and team leader shall enter the working face to check the gas, residual explosion, roof and other conditions. After confirming the safety, other personnel can be notified to enter the working face for operation

10. Open the spray in time before blasting, and spray water to eliminate dust after blasting

11. Mfb-200 type detonator is adopted. When the blasting is rejected by power on, the blaster must first remove the key or handle, and remove the blasting bus from the power supply, kinking it into a short circuit. After 15 minutes, the reason for the rejection can be found from the outside to the inside along the line. Article 342 of the coal mine safety regulations must be strictly followed when handling misfire and residual explosion

12. Charging and blasting are strictly prohibited in case of any of the following conditions before charging and blasting

(1). The roof control distance of the heading face does not comply with the provisions of the operating procedures, or the support is damaged, or the umbrella eave exceeds the provisions

(2). The gas concentration in the air flow within 20 meters near the blasting site reaches 1.0%

(3). Within 20 meters of the blasting site, more than 1/3 of the roadway section is blocked by mining cars, coal, gangue or other objects that have not been cleared

(4). Abnormal conditions, sudden high and low temperatures, significant gas emission and loose coal and rock were found in the blast hole

(5). The air volume of the working face is insufficient

13. Explosives and electric detonators must be packed and transported separately. Explosives are packed in the special explosive box of the working face, placed outside the warning line, with intact roof and no water spray, and away from live conductors. When shooting head-on, the production team will send people to take care of it, and the Gunners will take care of it at other times. Electric detonators are packed in small wooden boxes and kept by the shooters. The shooter must shift on site

14. The upper anchor rod lags behind the head-on 4 rows. Blasting is strictly prohibited

15. The minimum resistance line of blasting shall not be less than 300mm in rock roadway

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