(1) A sound is heard. When broken rock sinking dramatically increase the pressure on the roof, wooden stand will be issued splitting sound, followed by the emergence of the phenomenon of broken columns polybeam; metal pillar living under rapidly shrinking column, also loud sound.

(2) Dregs. When the top plate is severely ruptured, the top plate is slag-depleted, and the more slag is dropped, indicating that the pressure on the top plate is greater.

(3) The number of pieces of coal is increased. As the pressure on the coal wall increases, it becomes softer, and the coal is more than usual.

(4) Crack in the roof. The top plate has cracks and opens, and the cracks increase.

(5) The top plate appears to be separated from the layer. Check the top plate to use the "question top" method, commonly known as "knocking help top." If the sound is crisp, the top plate is intact; the top plate emits an "empty" sound, indicating that the upper and lower rock layers have detached.

(6) Leaking the top. Before the top of the roof, the broken pseudo-top or the direct top may sometimes cause a leaking roof due to the lack of the top of the back and the weak support of the bracket, forming the roof of the roof, and the bracket is loose and causing the roof to fall.

(7) There is water. The amount of water sprayed on the roof has increased significantly.

General precautions should be taken from the following aspects to effectively prevent the roof accident:

(1) and for an embodiment of roof brackets adaptation phase, different lithologies of the top plate to take a different embodiment of the stent. For example, the harder top plate can use the point column, while the soft and fragile top plate should use the shed, and the back plate and the bamboo raft on the back.

(2) Support in time after coal mining. After the coal mining machine cuts the coal, it is limited by the bending degree of the conveyor. In a certain range, the basic column cannot be hit in time, and the suspended surface of the roof is large. Therefore, it is generally necessary to use the method of hanging the metal beam or hitting the temporary pillar in time to support. Prevent local roofing.

(3) Take effective measures when moving the conveyor as a whole. The roof with a larger area cannot be supported by the pillars. For the relatively broken roof that is easy to fall, it is necessary to take corresponding measures, such as adopting the side-moving conveyor, the temporary support of the side pillars and the quick support and returning of the basic pillars.

(4) There must be special brackets on the working face and the lower exit. The upper surface of the working face has a large empty roof area and a long exposure time. Under the action of the leading support pressure, the roof sinks a large amount. In addition, when the nose and tail equipment move, the pillars are repeatedly removed, and the roof is easily broken. Therefore, it is generally necessary to add a shed or a raft in the upper and lower exits.

(5) Prevent the gun from collapsing the Yangtze. First, the arrangement of the blasthole must be reasonable, and the amount of charge should be appropriate. Second, the quality of the support must be qualified. It must be strong and strong, and should not be placed on the floating coal floating raft; the third is to leave the gun. If the gun collapses the column, it must be erected in time, and no empty roof is allowed.

(6) Adhere to regular circulation operations. The regular circulation operation stipulates that the daily progress of the working face, the control of the top distance, and the steps of the pillars and the returning column are sequentially performed. Therefore, the ceiling of the roof is small, the pressure is small, and the pillars are not easily broken to control the roof.

(7) Adhere to the necessary system. For example, the “knocking and asking top” system, the acceptance bracket system, the post responsibility system, the metal pillar inspection system, the roof analysis system, and the handover system, etc., prevent paralysis and avoid the occurrence of a roof accident.

(8) Adopt correct back-column operation method to prevent the roof pressure from concentrating to the local pillars, causing difficulties in local roof crushing and back-column work, strictly implementing the operating procedures and operating procedures, and strictly prohibiting illegal operations.

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