Abstract:
The coal base in western China is the core “ballast stone” of China’s energy security. In order to improve the resource recovery rate, the stability of small coal pillar open roadway is widely used. In this paper, the mechanical model of small coal pillar open roadway is established in Meidoushan Coal Mine of National Energy Group, and the correlation between the surrounding rock subsidence of small coal pillar and the supporting force of small coal pillar is quantified. The identification model of coal pillar stability is established by using naive Bayes model to judge the stability of coal pillar before and after regulation. Through the refined three-dimensional numerical calculation, the regulation effect of small coal pillar surrounding rock in open roadway is studied, and the field implementation is verified. The results show that there is a negative correlation between the maximum subsidence of the direct roof of the open roadway and the supporting strength of the small coal pillar by constructing four kinds of overlying rock structures at different fault lines. It shows that the subsidence of direct roof can be controlled by increasing the strength of small coal pillar, and the instability of surrounding rock of roadway can be improved. A coal pillar stability identification model was established based on naive Bayes and 11 surrounding rock parameters, and the accuracy of Ac reached 0.953 7, which met the identification requirements. The original coal pillar and the modified coal pillar are identified, and the feasibility of the control scheme is proved from the algorithm point of view. Through FLAC3D numerical simulation before and after the coordinated control scheme of surrounding rock modification, the stress value of coal pillar is increased by 57.6%, and the deformation is reduced by 22.8%. The stress of the supporting body is reduced, and the maximum displacement is reduced by 31.2%. The stress difference between the two sides decreases, and the stress distribution of roadway surrounding rock becomes more balanced. The in-situ implementation of the scheme can increase the maximum stress of coal pillar to 2.325 times, and the stress fluctuation is stable, and the deformation of roof and two sides is reduced by more than 80%. The feasibility of the coordinated control scheme of surrounding rock modification to prevent and control the deformation and failure of small coal pillar open-air roadway is verified, and the stability of surrounding rock is ensured. The research results provide basic support for the scientific design of small coal pillars in open roadway in western mining area, and provide reference for the prevention and control of the instability of open roadway with small coal pillars in western mining area.