Rock and carbon dioxide (gas) outburst risk prediction can be measured by core method or prominent aura. The core effect method should be used for the effect test.
Safety protection measures shall be implemented in accordance with the safety protection measures against coal and gas outburst.
2. When using the core method to predict the risk of rock and carbon dioxide (gas) in the working face, drill holes with a diameter of 50-70mm and a length of not less than 10m in the rock body in front of the working face, take out all the cores, and from the hole depth The number of discs in the core is recorded at 2m.
The method for judging the danger of working face is:
(1) When most of the cores taken out are 150mm or more and have cracks surrounding them, and some are small cylinders or discs, it is predicted to be a general dangerous zone;
(2) In the core of the lm length taken out, 20 to 30 discs appear in some cores, and the remaining cores are cylinders with a length of 50-100 mm and have annular cracks, which are predicted to be moderately prominent danger zones;
(3) When there are 20 to 40 convex and concave discs in the core of lm length, it is predicted to be a serious danger zone.
(iv) When there are no discs in the core and there are no annular cracks on the surface of the core, it is predicted that there is no danger zone.
3. When using the prominent omen method to predict the danger of rock and carbon dioxide (gas) in the working face, one of the following conditions is the dangerous working face of rock and carbon dioxide (gas):
(1) The rock is in the form of flakes or fluffy crumbs;
(2) After the working face is blasted, the footage exceeds the depth of the blasthole;
(3) There is obvious igneous rock intrusion or a significant increase in the amount of carbon dioxide (gas) in the working face.
4. When excavating roadways in rocks and carbon dioxide (gas) outburst dangerous rock formations, drilling parameters such as drilling blasting engineering optimization, advanced drilling, loose blasting, opening and unloading pressure grooves and setting fences near the working surface can be used to prevent rock and Carbon dioxide (gas) highlight measures:
(1) In the general or moderately prominent danger zones, shallow hole blasting measures or long-range multi-stage blasting methods may be used to reduce the vibration intensity of the rock mass and reduce the protruding frequency and strength. The long-distance multi-stage shooting method is to first make 6 snoring eyes and 6 auxiliary eyes on the working surface, which are arranged in an elliptical shape to form an elliptical advanced hole after blasting, and then blast the surrounding blastholes, and the blasthole distance is beyond the hole. Should be greater than 0.6m, the hole lead distance is not less than 2m.
(2) In the severely dangerous areas, advanced drilling and loose blasting measures may be used. The diameter of the advanced drilling hole shall not be less than 75mm, and the number of holes shall be determined according to the section size of the roadway, the occurrence of the dangerous rock formation and the effective radius of the single discharge drilling hole, but not less than 3, the hole depth shall be greater than 40m, and the drilling face shall be advanced. The safety distance must not be less than 5m.
Deep hole loose blasting hole diameter 60 ~ 75mm, hole length 15 ~ 25m, sealing depth is not less than 5m, the number of holes 4 ~ 5, of which 1-2 blastholes, other holes do not charge, to improve the loosening effect.
(3) When burrowing and shooting in the dangerous area of ​​severe rock and carbon dioxide (gas), a barrier shall be installed near the working face to limit the strength of the rock and carbon dioxide (gas).
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