Causes and prevention of accidental collapse of brackets and roof failure

First, the reason why the gun collapsed the bracket

(1) The quality of the bracket (column) is not good. Such as coal mining bracket face (column) is not enough to meet the mountain, wedge play is not tight, or the top free no brake tight, or will they play on the floating coal gangue; such as stents heading face Bangding recite Untrue, the column foot is shallow, the corner is too large or too small, or there is no support wood, pull strip, anti-backup, etc., the bracket is collapsed when the shot is fired.

(2) The arrangement of the blasthole is not compatible with the hardness and height of the coal seam. The collapse of the large coal causes the bracket to collapse.

(3) The angle of the blasthole is skewed, the blasthole is shallow, the charge is too much, the cannon is loaded less, the quality is poor, and the stent collapses when the shot is fired.

(4) The width of the tunnel of the coal mining face is small, too close to the bracket, and the bracket collapses when the gun is fired.

Second, measures to prevent the collapse of the cannon

(1) Before shooting, you must check the bracket and handle it. The top of the heading face should be inserted into the back, and the brace, struts or anti-backups should be applied to carry out the necessary reinforcement; in addition to strengthening the brake top, the support of the coal mining face should use tight wedges and struts. Ways to carry out the necessary reinforcement.

(2) Choose a reasonable method of grooving the face. The parameters such as the arrangement, angle and number of blastholes should be reasonably selected.

(3) The coal mining face should have a wide enough gun. The boring face should have sufficient grooving depth.

Third, the main reason for the fall of the gun

(1) The distance between the fundus and the top of the top of the mining face is too small or entered into the top plate, causing a roof when shooting.

(2) The mining work face encountered geological structure, the roof was loose and broken, and the method of placing small guns with less charge was not taken, and the shot was fired.

(3) The amount of charge in the top eye is too large, and the impact on the top plate is strong during blasting, causing roofing.

(4) The number of blasting blastholes exceeds the provisions of the "Operational Regulations", the area of ​​the empty roof is large, and the bracket fails to keep up with it in time; or when the blasting is performed, the slamming is not performed.

(5) The angle of the blasthole is not suitable. When the shot is fired, it collapses and collapses the pillar, resulting in a large area of ​​empty roof. The bracket does not keep up in time, causing the roof to fall.

(6) All the collapsed coal mining face does not take the old roof, and the coal roof has large cracks. When the roof is directly shot, the time, sequence and distance of the topping support are unreasonable, which can also cause roof collapse.

Fourth, prevention methods

(1) The blasthole fundus near the roof of the coal seam should be separated from the roof by a distance of 0.2 m to 0.3 m.

(2) According to the blasthole arrangement, angle, charge amount and blasting amount specified in the “Working Regulations” of the mining face, the work shall be prevented to prevent the collapse of the bracket, and the oversized empty top area and the empty top distance shall be formed.

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