According to the falling range of the top surface of the working face and the number of casualties, the top surface accidents of the working face are divided into two types: local roofing and large roofing;
Local roofing is generally caused by the fact that the direct roof that has suffered some degree of damage has not been timely supported or the bracket has not fully functioned or even failed. Affected by the original, geological structure, mining, etc., there will be many staggered fissures in the direct top, which will cause the continuity of the direct roof to be damaged to a certain extent. Thus, once the support is not timely or the support loses its function, the rock within the local range The block may fall and a local top will occur. Generally, one or several layers of similar properties directly above the coal seam are referred to as direct tops. There is sometimes a thin layer between the coal seam and the direct top, which is called a pseudo-top. Large-scale roofing occurs mostly during the initial collapse of the direct roof, during the initial pressure of the basic roof and during the surrounding pressure, or when the thick roof of the hard and difficult roof falls over a large area. This is because in the above case, the force of the bracket in the vertical layer direction and the parallel layer direction is much larger than usual, and if the support ability of the bracket is insufficient or the stability of the bracket is not good, it is easy to be crushed or pushed. Lead to large roofing.
According to the mechanical reasons of the roof, the top surface accidents of the working face are divided into four categories: leakage type, pressure type, push type and comprehensive type.
The skimmer-type roof is caused by the collapse of the broken roof without the effective protection caused by gravity; the collapsed roof is the roof caused by the top plate force in the vertical direction to crush the working surface bracket; the push-type roof is The roof collapse caused by the force of the top plate parallel to the direction of the plane; the integrated roof is the roof caused by two or more mechanical reasons.
Second, the main measures for prevention and control of roof accidents in coal mining face
1. The performance of the bracket should be compatible with the mining conditions such as roof roof and dip angle. The performance of the bracket should be adapted to the mining conditions such as roof roof and dip angle. It is essential to prevent roof accidents on the working face. Otherwise, it will not achieve good support effect or even lead to serious The topping. The performance of the bracket should have three aspects: support, protection and stability, namely: affordable, well protected and stable. The so-called support is to require the support to have a certain supporting force, but also has a certain shrinkage, so as to ensure that the support can support the pressure exerted from the direct top and the basic top when the pressure is applied, so that the support is not crushed due to the collapse of the support The so-called good protection is not only required to ensure timely and effective protection of the bracket, but also broken and known as the roof, which does not cause the roof to fall due to the leakage of the broken rock; the so-called stable is to require the bracket to have the ability to resist the thrust along the layer, without causing the bracket to be pushed down. Lead to the top.
2, to improve the level of mechanization of coal mining
Domestic and foreign data show that with the improvement of the mechanization degree of coal mining, especially the speed of the working face and the performance of the working face support, the roof is timely and effectively controlled, so that the roof accident is significantly reduced, and the casualties are greatly reduced. According to domestic statistics, more than 95% of the casualties in the roof of the working face occur in the blasting and general mining working face using the single bracket, but the fully mechanized mining face using the hydraulic support rarely occurs. Therefore, the coal mining is improved. The degree of mechanization is one of the important ways to prevent roof accidents.
3. Promote work surface support quality and roof dynamic monitoring technology
Through the quality of the supporting surface and the dynamic monitoring of the roof, the working condition of the working surface bracket and the state of the roof can be known and mastered in time, and the problems found can be dealt with or adjusted in time, so that the hidden dangers can be eliminated in time to prevent Suffering from it.
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