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a, impact push type roof. When the coal layer of roof separation, substantially by roof delamination fracture has hit the top of the slate stone seam, resulting thrust roof fall.
The main prevention and control measures are: dynamic monitoring of the roof, and the corresponding measures should be taken when the roof is separated. Improve the quality of support, enhance stability and level resistance. The support of the working face should be timely, improve the initial support of the stiffness of the bracket, and prevent the roof of the coal seam from separating.
b. Composite roof push-type roofing. The composite roof consists of rock layers and coal seams of different lithologies. When the lower layer of the composite roof has a small thickness of coal seam or rock formation, insufficient support strength, unqualified bracket quality or large mine pressure, it is easy to cause a composite roof push-type roofing accident.
The composite roof has no obvious signs and features before the roof is launched, and it may occur in any process. Therefore, the quality of the brackets should be strictly checked. The coal mines with conditions should be supported by hydraulic supports and the composite roof. Perform dynamic monitoring.
c, general preventive measures
It is possible to control the mining height so that the soft rock layer falls behind the hard top. Do not destroy the composite roof for mining work. According to the actual work experience, the pseudo-tilt working face is applied. When erecting the truss and truss, it should be supported in the direction of possible movement of the rock mass.
Pipe fittings are used to connect pieces of pipe together. Pipe fittings connect to pipes in one of two ways: by threads or by slip fit. Metal pipes are threaded, while plastic pipe can be threaded or slip fit. As the names indicate, threaded pipes screw together to connect, while slip fit pipes use sleeves that slip into one another. They are organized by male and female connectors.
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