Microwave heating L-type method for reducing composite strong mine pressure of thick hard roof and left coal pillar

Abstract

The invention discloses a microwave heating L-type method for reducing the composite strong mine pressure of a thick hard roof and a left coal pillar, and belongs to the technical field of coal mining. The method combines microwave heating with coal mining, and an L-shaped well is drilled in the ground right above a residual mining area left coal pillar; when microwave (electromagnetic wave with the frequency of 300 MHz-300 GHz) acts on a rock body, an electromagnetic field applies energy to the rock body in a form of wave, and the energy is converted through the heat absorption of the rock, so that similar friction is generated inside an object, the temperature is increased, and the rock body is cracked under the combined action of internal stress generated in the rock body, evaporation of water in the rock body, decomposition and expansion of substances and the like. The method fully utilizes the characteristics of high efficiency, large energy density, wide adaptability, strong penetrability and the like of microwave heating rock breaking, realizes double functions of one well, enables pre-splitting on a thick and hard top plate of an underlying coal bed and the residual coal pillars in a residual mining area, and achieves the purpose of reducing the composite strong mine pressure of the thick and hard top plate and the residual coal pillars in the residual mining area.

Description

technical field [0001] The invention relates to a microwave heating L-type method for reducing the composite strong mine pressure of a thick and hard roof and left coal pillars, and belongs to the technical field of coal mining. Background technique [0002] Most of the coal mines in my country use the downward mining method, that is, the overlying coal seam is mined first and then the underlying coal seam is mined. When the underlying coal seam is mined, it will pass through the thick and hard roof between the layers and the remaining coal pillars in the overlying residual mining area, and the coal mining work will be affected by the combined strong mine pressure. [0003] Composite strong rock pressure mainly comes from: (a) thick and hard roof: due to natural geological conditions, the underlying coal seams in many mining areas have thick and hard roofs with large thickness, high strength, no joints and fissures, and good integrity; (b) residual Remaining coal pillars in ...

AI Technical Summary

Problems solved by technology

[0004] When mining the underlying coal seam affected by the thick and hard roof and the combined strong mine pressure of the remaining coal pillars in the residual mining area, the mine pressure on the working face will be strong, the working face will be severely swollen, and the roof of the gob will collapse violently accompanied by huge The pressure of the support on the working face increases significantly, the support is crushed, and the single pillar of the roadway is damaged from time to time. Moreover, the initial / period pressure step distance of the thick and hard roof in the stope will also increase, and a large amount of energy will be accumulated. When mining When the thick and hard roof of the field suddenly falls, the accumulated energy will be released instantly, which will cause severe impact dynamic disasters, cause equipment damage, casualties, and seriously endanger mine safety production

[0005] It is difficult to predict and prevent the combined strong mine pressure caused by the thick and hard roof and the remaining coal pillars in the residual mining area. The current control method for the combined strong mine pressure in the underlying coal seam affected by the thick and hard roof and the remaining coal pillars in the residual mining area There are: a. Passive control method: (1) Adjust the mining direction and layout orientation of the working face of the underlying coal seam, so as to avoid the concentrated stress affected area of ​​the remaining coal pillars in the residual mining area, but the working face is still affected by the pressure of the thick and hard roof , did not solve the problem fundamentally; (2) Strengthen the support of the working face of the underlying coal seam, but when the mine pressure of the working face is strong, it is difficult to ensure safe production through simply strengthening the technical measures of the support, and the support High cost; (3) Larger coal pillars are also left in the underlying coal seam working face affected by the thick and hard roof and the remaining coal pillars in the residual mining area, but this causes a great waste of coal resources; b. Active control method : (1) Blasting is carried out in thick and hard roofs and coal pillars left in residual mining areas, but the construction volume is large and the controllability is poor, especially for high-gas mines, which are prone to gas explosions and have potential safety hazards; (2) Using water pressure blasting Fractured thick hard roofs and residual coal pillars in the residual mining area consume a lot of water resources, and the chemical reagents in the high-pressure fracturing fluid during the fracturing process are likely to pollute the downhole environment

It can be seen from the above control methods of composite strong rock pressure that the passive control method is not effective and does not really solve the problem; the construction site of the active control method is mostly in the working face or in the roadway, which affects the coal mining work, and it is necessary to crack thick and hard rocks separately. Roof and remaining coal pillars in the residual mining area, the steps are cumbersome

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