Study on influence law of room and pillar gob on pressure behavior of lower seam mining

In order to understand the influence law of irregular coal pillars in the room and pillar gob on the mine pressure appearanceof lower seam mining, a numerical simulation method was used to study the relationship between the integrity of coal pillars and the mine pressure appearance in the gob, by means of physical similarity simulation, the movement and breakage of overburden on the coal face with different integrity conditions were compared and analyzed,and the influence mechanism of coal pillar integrity and high and low position masonry beam structure stability on mining pressure was revealed by theoretical analysis, and the influence mechanism of re-mining pressure has been verified through on-site observation. The results show that there are two main factors that influence the mine pressure appearance: ①the integrity of the coal pillars in the room and pillar gob, the higher the integrity, the stronger the mine pressure appearance will be; ②the stability of the high and low masonry beam structure, when the coal pillars in the room and pillar gob are intact, under the combined action of high and low masonry beam structure, the mining pressure is very strong; however, the low level masonry beam structure is easily affected by mining during the lower layer re-mining process, which causes the structure to slide and lose its stability, thereby greatly reducing the strength of the rock pressure; The on-site rock pressure is obviously different, when the overlying coal pillars are complete, the intrusive pressure strength exceeds 35 MPa, most of the mining face can be observed with complete roof. The integrity of the roof can be used as a precursor to the appearance of mine pressure, once complete area of the roof is found, the support of the working face should be reinforced in time and advanced drilling should be carried out to weaken the complete coal pillar by technical means, so as to control the intensity of the appearance of mining pressure and prevent the occurrence of mine safety accidents. The research results can provide reference for the prevention and control of mining pressure under similar conditions.