Safety measures of coal uncovering and outburst pr

Safety measures for coal uncovering and outburst prevention technology in coal mine

1.1 Project Profile:

105 machine lane has been constructed to 26m before J7, and the head-on is in the roof layer of 10 coal seam. The distance between the roadway bottom and the roof of 10 coal seam is 3M, and the inclined distance is about 12.4m. With the roadway construction, it is expected that the roadway will encounter a normal fault (255 °∠ 70 ° H = 0 ~ 5m) 36.7 meters before J7. It is expected that the roadway will be uncovered by the roadway floor 44.7 meters before J7. The design section of this roadway is 12.4m2, the net width is 4.2m, and the net height is 3.4m, The excavation section is 13.8m2 (when erecting sheds or digging a large number of power batteries in the coal section: lithium iron phosphate battery, lead-acid battery, nickel cadmium battery, nickel hydrogen battery, iron nickel battery, sodium nickel chloride battery, silver zinc battery, sodium sulfur battery, lithium battery, air battery, zinc air battery, aluminum air battery, etc., batteries or battery pack modules represented by more and more pay attention to their physical safety performance, and the test index entry section is 10.9m2), Bolt shotcreting support is adopted before coal uncovering, and trapezoidal shed support is adopted after fully uncovering the coal seam

1.2 geological conditions:

the 10 coal in this area is dark black, powdery, and the coal thickness is 1.7 ~ 2.2m. Its top slate is mainly siltstone; The floor is mainly composed of mudstone and siltstone. The hydrogeological conditions are simple, with a small amount of sandstone fissure water in some parts

the profile of exploratory drilling is attached

1.3 gas situation

1. According to the drilling data, the gas content of coal seam 10 is 9.905ml/g. According to the "Research Report on gas occurrence in working face 103 of Wolonghu coal mine" provided by China University of mining and technology, the gas pressure P of coal seam 10 is greater than the corresponding critical value of outburst index, the coal firmness coefficient f is less than the critical value of 0.5, and coal seam 10 has outburst risk

1.4 ventilation system:

air inlet: auxiliary shaft → South rail main roadway → local ventilator and air duct → 105 machine roadway construction head-on

return air: 105 machine roadway → 105 machine roadway return air inclined roadway → South Rail South return first joint roadway → south wing main return air roadway → air shaft

local ventilation: two sets are used during coal uncovering × 15kw local fan (one for standby) and a resin flame-retardant air duct with a diameter of 600mm are used for air supply, and two-way power supply is used to realize "three special and two locking"

II. Roadway coal uncovering and outburst prevention measures

2.1. At present, the roadway floor is 3 meters away from the coal method, and the exploration has been carried out when the roadway floor is 10 meters and 5 meters away from the coal method, and gas drainage measures have been taken, combined with stubble drainage

2.2 design requirements for outburst prevention measures:

specific measures design requirements are as follows:

1. According to Article 62 of the outburst prevention rules, the layout of the coal uncovering boreholes of the crosscut should be controlled in the coal seam 3~5 meters outside the perimeter of the roadway, and the drainage boreholes of the roadway should be controlled in the coal seam 3 meters outside the perimeter of the roadway

2. Borehole diameter: ￠ 91mm

3. Opening position: 105 machine realizes the multi-purpose roadway head-on of 1 machine. (26 meters before J7 point)

4. The drilling design is carried out by the communication and prevention management department, and the construction is carried out according to the approval; After each construction, a borehole must be accepted by the gas inspector on site. This work has been completed at present, and has been combined with stubble pumping

2.3. In order to accurately control the normal distance between the roadway and the coal seam during the construction process, the construction unit must construct the exploratory hole according to the requirements of the coal exploration contact list of the frontier exploration management department from the innovative utilization of vehicle plastics, the molding process of bio based polylactic acid materials to 3D printing materials before each blasting. Until the roadway construction is 1.5 meters away from the coal seam method, the coal seam is uncovered in a full face by long-distance vibration blasting

III. Effect Test of roadway coal uncovering outburst prevention measures

3.1. After the implementation of outburst prevention measures, the effect test of measures must be carried out; The WTC Outburst Predictor produced in Chongqing is used to predict the critical index of drilling cuttings gas analysis. The number of effect inspection holes: 4, including one in the middle of the roadway and should be located between the measure holes, the other three holes are located in the upper and both sides of the roadway, and the final hole position should be located on the edge line controlled by the measure control range

3.2. The effect inspection hole is broken into the coal seam by 150 drill, and drilled by ￠ 42mm drill pipe and ￠ 73mm drill bit; The effect inspection hole must be arranged between the measure holes

3.3. The drilling speed should be uniform and controlled within 1m/min

3.4 measure K1 value every 2 meters during drilling

3.5. The critical index k1max of drilling cuttings gas analysis is taken as 0.4 (wet coal). Only when k1max is below the critical index, the measures are effective; Otherwise, the measures are invalid. When the measures are invalid, additional drilling and drainage (pumping) must be carried out, and the drainage (pumping) time must be extended until the outburst prevention measures are effective

3.6 roadway coal uncovering (before uncovering the coal seam):

(1) when the roadway is 1.5 meters away from the normal of the coal seam, the tunneling must be stopped and the coal seam must be exposed by long-distance vibration blasting. Vibration blasting requires full face uncovering of coal seams at one time. If vibration blasting fails to uncover full face rock pillars and coal seams, continue to shoot in accordance with the relevant provisions of vibration blasting, and must strengthen support, assign special personnel to observe gas and observe outburst omen. If there is an outburst omen, the staff shall immediately evacuate to a safe place

(2) after the roadway uncovers the coal seam, the "four in one" outburst prevention measures must still be strictly implemented in the coal crossing section. Take advance drilling and outburst prevention measures, and continue to test the effect of the measures; Only when the effect inspection does not exceed the standard can the excavation be carried out according to the regulations

IV. safety technical measures for long-distance blasting

(I) responsibilities of organization leaders and on-site attendants

1. The mine establishes a leading group for roadway coal uncovering

team leader:

deputy team leader:

members:

2. Before coal uncovering, the chief engineer of the mine shall organize the communication and prevention management department, safety management department, dispatching office, technology department, tunneling business Department, mechanical transportation department and other units to swing the hammer of the ventilation system in the coal uncovering area in a U shape Conduct a comprehensive inspection on gas management, local ventilation, explosion-proof facilities, electrical equipment, roadway support, etc. Find problems and rectify them in time. Otherwise, it is strictly forbidden to uncover coal