Study On Characteristics And Maintenance Of Shaft Damage Due To The Extraction Of Industry Square Pillar

As the throat of coal mine, the stability of shaft is very important. Meanwhile, the coal within the shaft and industry square pillar is great huge. This thesis is aimed at studying the effect of the extraction of industry square pillar on the auxiliary shaft in Xiangshan Corp. Through the probability integral method, the displacement and strain of industry squre and shaft were predicted, using MATLAB. Under different mining technologies of shaft pillar, the characteristics and law of the shaft damage were further studied as well, with the numerical simulation software of FLAC3D. When the coal is excavted, upper shaft has compressive strain in radical direction for the strata squeezes the shaft; lower shaft has tensile strain in radical direction for the surrounding rock has the trend of moving towards the goaf. The upper shaft has tensile strain in vertical direction, but there is no failure. The lower shaft has compressive strain in vertical direction, and it fails. Under special mining methods, the shaft still has some stress concentration, which will not bring failure. According to the effect of each factor on the shaft due to the extraction of shaft pillar, the factors are ranked as following from serious to slight: mining method of the working face between dimetric pillar and shaft protective pillar > size of the dimetric pillar > mining direction of the working face between dimetric pillar and shaft protective pillar > mining method of the working face between dimetric pillar and closed pillar. According to the field survey, shaft fracture belongs to the combination of vertical compressive failure and horizontal section failure. The main reason is that the strata were unstable when the shaft was built, due to the extraction of working face. Since the configuration of the fracture area is"one soft stratus between two hard strata", the vertical and horizontal stresses within the soft stratus were huge and the shaft broke in vertical and horizontal direction at last. This is also the reason why the north shaft fracture was more serious. The shaft fracture was solved through the method of the combination of"bolting, wire netting, and channel steel".