How to prevent and control roof falling accidents

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How to prevent roof fall accidents

underground roof fall is the most common and prone accident in coal mines. Under normal circumstances, roof fall accidents have the following warning signs in advance:

(1) sound. When the strata sink and fracture, and the roof pressure increases sharply, the wood support will make a splitting sound, followed by the phenomenon of broken beams and columns; The movable column of the metal pillar shrank rapidly and made a loud noise

(2) slag falling. When the roof is seriously broken, there is slag falling from the roof. The more slag falling, the greater the pressure of the roof and adjustment pointer

(3) the number of sliced coal increases. As the pressure on the coal wall increases, it becomes soft, and there are more sliced coal than usual

(4) roof cracks. The roof has cracks and opens, and the cracks increase

(5) roof separation. Check the top plate by asking for the top, commonly known as knocking on the top. If the sound is clear, the roof is intact; The roof makes an empty sound, indicating that the upper and lower rock layers have been separated

(6) top leakage. Before the large roof fall, the broken false roof or direct roof sometimes leaks because the back roof is not tight and the support is not firm, forming a ceiling supporting space, and the support is loose, resulting in roof fall

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

general preventive measures should be taken from the following aspects in order to effectively prevent roof fall accidents:

(1) the support method should be adapted to the lithology of the roof, and different support methods should be adopted for the roof of different lithology. For example, point columns can be used for hard roof, while shed 7 is used for soft and fragile roof Press the "OK" key, and insert the back plate and bamboo fence on the beam

(2) support in time after coal mining. After the shearer cuts coal, due to the limitation of the curvature of the conveyor, it can't hit the basic column in time within a certain range, and the hanging surface of the roof will be large. Therefore, it is generally necessary to use the method of hanging metal beams in advance or hitting temporary pillars for timely support to prevent local roof fall

(3) take effective measures when moving the conveyor as a whole. The roof with a large area cannot be supported by pillars. For the relatively broken roof that is easy to fall, corresponding measures must be taken, such as moving the conveyor, returning the temporary pillars and supporting the basic pillars at the same time

(4) there should be special supports at the upper and lower exits of the working face. The upper and lower outlets of the working face have large empty roof area and long exposure time. Under the action of advance support pressure, the roof subsidence is large. In addition, when the head and tail equipment move, the pillars are repeatedly supported and removed, and the top plate is easy to break. Therefore, it is generally necessary to add a shed or wooden crib within the upper and lower exits

(5) prevent shooting collapse of Yangtze River. First, the arrangement of blast holes must be reasonable and the charge quantity must be appropriate; Second, the support quality must be qualified, firm and strong, and cannot be hit on the floating coal and gangue; The third is to set aside the gun path. If the blasting collapses the column, it must be erected in time, and no empty roof is allowed

(6) adhere to regular circular operation. The regular circulation operation stipulates the daily progress of the working face. The fixture should not cause the sample to break at the fixture, control the distance between the top and the pillar, return the pillar and other processes in sequence. Therefore, the roof has small exposed area and low pressure, and the pillar is not easy to break, so as to control the roof

(7) adhere to the system that requires the strength and modulus of low-density materials, the activity and stiffness of thin-walled materials, and the fiber content of glass fiber reinforced materials. For example, the system of knocking on the side and asking for the top, the system of accepting the support, the post system, the metal pillar inspection system, the roof analysis system and the shift system can prevent the occurrence of roof fall accidents by preventing carelessness

(8) adopt the correct operation method of column return to prevent the roof pressure from concentrating on local columns, causing local roof breakage and difficulties in column return. Strictly implement the operation procedures and operation procedures, and prohibit illegal operations

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