The B1302 work surface has been installed and will be commissioned for production in the near future. The surface is in the triangular area enclosed by the 1302 and 1303 goafs and the Guanzhuang No. 2 fault (12-18m drop). The surface is evaluated for medium impact risk, and the working surface is impacted according to the impact risk index. The hazard is divided into five areas (as shown in the figure), of which, one area is a special key anti-shock area, two areas, four areas, and five areas are key anti-shock areas, and the third area is a general anti-shock area. In order to ensure the safety during the mining period, the impact ground pressure monitoring and treatment plan and safety technical measures are specially prepared.
First, the impact of ground pressure monitoring content and methods
1. Internal stress monitoring of coal
In the working face, the upper and lower rails were installed with 15 borehole stress gauges, and the rails were installed with 10 sets of borehole dynamometers to monitor the internal stress changes of the coal body. The borehole stress gauge has a spacing of 5 to 10 m and a hole depth of 4 to 10 m. During the production of the working face, according to the change of the stress of the coal body, it is observed once every 1-2 days. When the stress changes obviously, the frequency of observation is properly encrypted, and it is observed every day, every shift or interval of 0.5 to 2 hours.
2, coal powder quantity detection
After the working face began to advance, the pulverized coal amount was monitored by the drill cutting method in the 60m range of the coal wall of the coal face of the coal gangway and the front side of the coal sluice face, and each drilling hole of each sluice was not less than 5 sets. According to the change of coal powder quantity, it is monitored once a day or every shift.
Detecting hole arrangement: the diameter of the hole is 42mm, the hole depth is 10m, the spacing is 10~15m, the hole is about 1.2m from the bottom plate, and the single row is arranged. The drilling direction is parallel with the coal seam and the vertical lane.
Implementation method: using pneumatic drill hole punching, threaded connection twist drill pipe, each section length 1.0m, φ42mm drill bit, collecting the pulverized coal powder with cement bag, measuring the weight of pulverized coal with spring balance, each drilling 1m Measure the amount of drill cuttings once. A special form is used to record the location, time, and cuttings discharge, and the dynamic phenomena such as drill pipe runout, stuck drill, suction drill, splitting sound and micro impact appear during the drilling process.
The index for determining the impact risk of the workplace using the amount of coal powder can be implemented in accordance with the provisions of the following table. Within the measured depth of the borehole listed in the table, the actual drilling rate reaches the corresponding index or the stuck rod is stuck, which can be judged as the impact risk.
Drilling rate indicator for determining the impact risk of workplace
Drilling depth / coal seam thickness | 1.5 | 1.5-3 | 3 |
Drilling powder index | ≥1.5 | 2-3 | ≥4 |
Note: (1) Drilling rate index = actual pulverized coal per metre / normal pulverized coal per metre
(2) The normal amount of coal powder can be measured in the normal stress zone
3. Deformation observation of surrounding rock of roadway
Before the production of the working face, based on the observation base of the surrounding rock deformation during the excavation, the advanced working face 30m is set in 6 sets of observation base points in the two grooves, arranged by the cross cloth point method, the spacing is 10m, and the sinking amount is measured by the measuring gun. And the two groups moved closer, and observed once a day.
4, working surface support load observation
In the 5#, 17#, 28#, 32#, 43#, and 57# brackets of the working surface, 6 sets of mine digital pressure gauges (ie, computer circular diagrams) were installed, and the change status of the initial support force and the end-of-cycle resistance of the support was continuously recorded. And size, in order to analyze the law of roof movement and the strength of mine pressure.
All data observed must be collated and analyzed in a timely manner to guide the production of the work surface.
Second, the impact of ground pressure risk management program
1. Precautionary pressure relief measures shall be implemented in advance. Before the production, the production will be carried out in the rails and the gangs will be used to construct 69~110mm drill holes. The drilling position is 1.2m from the bottom plate, and the drilling length is L=12m. 5m.
2. Carry out coal seam water injection ahead of time, and apply coal seam water injection hole on the side of the working face, with a spacing of 15m, a hole diameter of 51mm, a hole depth of 2/3 plus 15m, a sealing depth of 10m, and the water injection amount increases the coal body moisture. The rate reached 1% to calculate the single hole water injection. Water injection is carried out by means of static pressure water injection, 20 to 30 m ahead of the working face. See the special measures for coal seam water injection.
3. When the amount of coal powder and the internal stress of the coal body are monitored in the area where the pressure is abnormal, the blasting pressure relief method shall be implemented in time to relieve the pressure. For specific construction, it is necessary to prepare special safety measures for anti-pressure relief.
1) Blasting drilling arrangement: the drilling distance is 5m, which is staggered from the previous large diameter pressure relief hole and water injection hole.
2) Drilling depth and charging method: the depth of the blasthole is 10-15m. Due to the large amount of pores, multiple detonator connections are used to enhance detonation. In order to make the medicine roll to the bottom of the hole, the plastic pipe is used to charge the plastic, the end of the plastic pipe is plugged with tape, and the reverse coupling charge is used, and the non-charged part of the hole must be filled with the clay cannon.
3) Charge: mineral water glue explosive, the length of each hole is 6-8m, the length of the seal is 4-6m, and the charge is reversed.
4) Preparation of the drug: the detonator and the mine water glue explosive are used together to make the gun head. The detonators in each hole are connected in parallel, and the holes are connected in series (when porous blasting is used). The detonator in each hole of the blasthole must use a dedicated millisecond delay electric detonator of the same segment.
5) Number of holes and requirements:
The number of blasting holes in each group is 5, the spacing is 5m, the direction of the drilling is vertical, and the blasthole is arranged in a single row, about 1.2m from the bottom plate.
After the blasting pressure is relieved, the drill cutting method should be used for monitoring and verification. If there is still a pressure concentration abnormality, the blasting will continue between the original drilling holes, and then the effect will be checked until the danger is removed.
Fourth, the impact of ground pressure protection safety technical measures
1. Anti-crush monitoring and fire-fighting work must be based on the impact and pressure control plan and relevant regulations to prepare special construction workers measures, and organize the implementation of relevant measures to communicate learning.
2. All personnel working in the impact hazardous area must be educated about the impact pressure ground pressure, familiar with the causes, conditions, symptoms and emergency measures of the impact pressure. The high-risk anomalies are found on the spot. The bottom of the drum and the roof sinking seriously) must immediately organize the evacuation, report the shift and dispatch room, and obey the command and arrangement of the anti-shock management personnel.
3. The working unit of the construction unit must first check and work after reaching the impact danger area. Before the construction, the head of the shift and the head of the shift (group) must carefully check the safety situation of the work place and the exit of the road, and find that the problem is dealt with in a timely manner. If the support is not perfect, it must be strengthened and ensured, and the road is smooth.
4. All personnel should pay attention to the observation of the top and the pressure changes at any time. When there is a sign of impact pressure or a notice of evacuation, it is necessary to evacuate the site in time and enter a safe place.
5. Strictly implement the system of knocking and helping the top, first supporting the back, and knocking the top of the question to use special tools with a length of not less than 1.5m.
6. Strengthen the management of the working face and the top and top of the two ends. When the top plate is complete, the support must reach the initial support force. When the top plate is broken, the advance support support top plate is pulled in time, and the material maintenance is performed if necessary.
7, single prop must adopt reliable prevention method, all the pillars of the rope must be linked anti-down, no less than two, and with a double-stranded No. 12 iron wire or other means to each of them with a single prop top Network of prison.
8. Clean up the debris and keep the outlet open. It is forbidden to store rigid materials and equipment in the advanced support area. Equipment, pipelines, etc. that cannot be transported out must have rooting measures (fixed with wire rope or wire), and partially tightened and partially relaxed.
9. All personnel must use labor protection articles as required, wear safety helmets, work clothes, belts, miner's lamps, self-rescuers, etc.
10. Each class is assigned to be responsible for inspecting the roof of the roadway and discovering that the top network and the help network are broken in time to make up the joint. A single pillar is supported under the steel strip in the sinking area of ​​the roof of the roadway for reinforcement support.
11. The construction materials should be placed at the bottom of the roadway floor as much as possible, and the yards should be placed neatly.
12. When impact pressure occurs, all personnel must choose the shortest route and the fastest speed to get out of the danger zone.
The specific disaster avoidance route is: working surface → track (transportation) along the trough → one mining area connecting lane → -450 main lane → ten mining three horizontal track lane → ten mining monkey car road → bottom hole yard → ground
13. Strengthen gas monitoring in hazardous areas, find abnormalities and report in time. Assist with other relevant units to do a good job in monitoring and controlling the impact pressure.
14. Confirm that the area with impact danger must be set with a striking impact pressure warning sign, indicating the precautions of the operators in this area, and irrelevant personnel are strictly prohibited from staying in the area.
15. When blasting operation or drilling pressure relief operation is carried out in the dangerous section of the impact ground pressure, the distance between the cannon and the time of cannoning must be guaranteed. The radius of the cannon is not less than 150m, and the time of dozing is not less than 30 minutes.
16. When there is danger in the impact of an area or the work is being carried out, it is strictly forbidden to enter the area and the relevant equipment shall not operate.
17. The personnel who are working in danger and the operators in the impact danger area should pay attention to the changes of surrounding rock movement at all times, find that the abnormality is immediately withdrawn, and set a warning, and report the situation to the mine dispatching room in detail.
18. In the impact danger area, the two sides of the coal mining face on both sides of the support range of coal cutting and moving, the support section and the non-post staff in the terminal triangle are strictly prohibited from entering.
19. The following situation occurs in the drilling location. The personnel are first evacuated to a safe place. After the pressure is stabilized, the follow-up personnel check and confirm that there is no danger before monitoring the coal powder.
(1) There is a large coal body protruding, and the coal wall suddenly blows out.
(2) The coal wall has continuous explosion, the coal cannon sounds constantly, and the surrounding rock activity is obviously intensified.
20. Other unfinished matters shall be strictly implemented in accordance with safety regulations, operating procedures and other relevant regulations.
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