Study On Borehole Stability Of Sealing Segment Of Coal Seam Gas Drainage

In domestic, drainage boreholes of coal seam are widely used foaming polyurethane sealing methods. Foaming polyurethane has lower strength and larger decrement, and the boreholes are not effectively support, causes drainage borehole gas leakage. To solve this problem, my teacher puts forward to one kind new sealing method:pocket assay grouting sealing method. This paper study the stability of borehole with pocket assay grouting sealing method, at the same time, the author makes contrast research on the polyurethane sealing. At first, the author against those two kinds of sealing method, put foaming polyurethane and expanded cement, which fill the borehole, as the support material of borehole, takes the mechanics parameter of foaming polyurethane and expanded cement as the foundation, the displacement vector around the borehole and the fractured zone closed to the borehole were studied by means of theory of gateway support; then the distributions of displacement and yield zone around the borehole have been analyzed by using of FLAC3D, and the simulation results of those two kinds of sealing methods have been compared with each other and studied; at last,the author uses the self-made test apparatus, researches deformation restraining situation of borehole and the fracture development around the borehole in loading condition. Such conclusions can be drawn:the foaming polyurethane sealing methods almost no supports function to the borehole, plastic zone and development of the borehole quite big, a lot of crevasses to produce around borehole in loading condition; pocket assay grouting sealing method can provide the initiative supports strength to the borehole, plastic zone and development of the borehole slightly, the crevasse around the borehole are very few. Research explains pocket assay grouting sealing method is a superior method to foaming polyurethane sealing method.