关键词: 井筒变形, 围岩强度劣化, 内聚力损失, 井壁修复

Abstract: Coal mine shaft is a key part to ensure smooth production, and its deformation of surrounding rock to failure and damage is still one of the main forms that affect the safety of coal mine production. In view of the weathering, cracking and bulging deformation problems of the Jijianao inlet air shaft of Xinyuan Mine, the geological and production conditions and stress environment of the site were investigated in depth, and the damage factors were analyzed and concluded the complex regional stress distribution, the deteriorated rock conditions, the corrosion and weathering of the shaft walls and the unreasonable support method, and it is pointed out that the deterioration of surrounding rock strength in weak strata, the loss of well wall strength caused by well wall corrosion and weathering, and the unreasonable support method are the main reasons for the deformation of the well wall. According to the field conditions, the changes of the stress environment around the shaft are analyzed in detail, including the increase of the additional stress the horizontal force on the shaft wall. The increase of the additional stress is due to the subsidence of the formation caused by the hydrophobicity of the aquifer, and the increase of the horizontal stress is caused by the attenuation of the rock cohesion caused by the deformation of the surrounding rock; In terms of the strength and deformation of the shaft enclosure structure, through the establishment of the mechanical model of the shaft structure, it is concluded that the damage condition of the shaft is that the horizontal force of the shaft wall exceeds its allowable stress limit value. Deformation and damage of the shaft may occur in the rock mass, and two specific directions for repairing the shaft and maintaining its safety are proposed accordingly. On the premise of synthesizing the advantages and disadvantages of various repair technologies, the comprehensive repair plan is proposed including grouting, prestress grouting anchor cable and shotcrete, and then detailed grouting and prestressed anchor cable support parameters are designed, and the construction process of shaft wall repair is formulated. Finally, a long-term deformation observation was implemented after the project was carried out on site, and the results showed that this scheme could maintain the shaft safety and stability.