in shock ground pressure mines
When mining shock ground pressure coal seam, two working faces shall not be arranged in the stress concentration area to carry out mining operation at the same time, and one of the working faces shall be stopped when the distance between two digging faces is less than 150m, when the distance between coal mining face and digging face is less than 350m, and when the distance between two coal mining faces is less than 500m. Mining interactions between neighboring mines and adjacent mining areas should be avoided.
Reasonable arrangement of roadway and mining in shock ground pressure mines
Open cuts must not be located in seams with severe impact ground pressure, and permanent chambers must not be located in seams with impact ground pressure. Coal seam roadways and chambers should not be constructed with bottom coals, and if bottom coals are present, measures must be taken to pre-pressurize the bottom slabs.
Roadways in thick seams with severe ground pressure should be located outside the stress concentration zone. The two parallel roadways should be avoided to affect each other in time and space when digging double roadways.
The impact ground pressure coal seam should be mined in strict sequence, and no isolated coal pillar should be left. No coal pillar shall be left in the air space, if it is necessary to leave a coal pillar in the air space, it shall be demonstrated and reported to the technical person in charge of the enterprise for approval, and the position, size and influence range of the coal pillar shall be marked on the plan of the mining project. Mining island coal pillar, should be anti-shock safety mining demonstration; serious impact pressure mine shall not mine the island coal pillar.
Impact ground pressure on the coal seam, should be based on the top and bottom of the lithology of the appropriate increase in the width of the roadway. Priority should be given to the selection of no coal pillar protection process, the use of large coal pillar protection should avoid the stress concentration area, it is strictly prohibited to leave a large coal pillar to affect the neighboring layers of mining. Rigid support is strictly prohibited in the roadway.
When using the collapse method to manage the roof, the support (pillar) should have sufficient support strength, and all pillars in the mining area must be returned to the net.
Special measures must be formulated when the impact ground pressure coal seam digging work faces near large geological formations, mining hollow areas, and other stress concentration areas.
It should be clearly stipulated in the operation regulations that the anti-impact measures should be taken during the period of initial pressure, periodical pressure, and "square" of the mining hollow area.
When mining and recovering coal pillars in the area surrounded by the air-mining zone on three or four sides in the coal seam without impact ground pressure, special anti-shock measures must be formulated.
Explanation of implementation
Stress is a necessary condition for the occurrence of impact ground pressure, and mining activities will lead to changes in the distribution of stress in the coal (rock) body and an increase in the concentration of stress.
Within the range of concentrated stress, if two working faces are arranged for simultaneous mining or digging, the supporting pressure of the two working faces will be superimposed, and its value will increase exponentially, which is very easy to induce impact ground pressure. Therefore, in order to avoid the impact of ground pressure coal seam mining, digging face in time, space and mutual interference, the working face should be left between the mining and digging enough stagger.
When the double lanes are digging at the same time, in order to avoid the mutual interference of the two parallel lanes in time and space, the stagger between the front and back of the double lanes should be more than 150m.
Both sides of the working face and above the boundary of the two sides for the hollow area, called the island working face. Influenced by the superposition of support pressure in multiple directions, the mining stress level of the island working face is higher, the top plate movement is intense, and the risk of impact ground pressure is higher.
After the work face is mined back, the length of the hollow area is approximately equal to the tilted length of the work face, i.e., the hollow area is "square". The overlying rock layer is positively "O-X" broken, the stress concentration is high, and the mineral pressure is obvious, which is the key prevention and control stage of impact ground pressure.
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