Research on design of small diameter TBM cutterhead in gas control roadway of Well 1 Bailongshan Coal Mine

Well 1 of Bailongshan Coal Mine is a coal and gas blow-out mine, the use of full-face tunnel boring machine (TBM) can better meet the needs of safe, efficient and environmentally friendly construction of coal mines. The cutterhead is a key component to determine the efficiency of TBM construction, and its reasonable design is essential to ensure the safety of coal mine production. Based on the analysis of the differences in engineering demands and geological characteristics between coal mine gas control roadway and non-coal mine tunnel, the design requirements of TBM cutterhead in coal mine gas control roadway are summarized, and the design process of TBM cutter head in gas control roadway is illustrated. The small diameter TBM cutterhead is designed for the gas control roadway in Well 1 of Bailongshan Coal Mine, and the initial scheme of the cutterhead is determined from three main aspects: the body structure, the layout of the cutters, and muck removal structure, then, the scheme of cutterhead is finally formed in combination with the verification of overturning moment, unbalanced force, strength and stiffness. The TBM cutterhead of gas control roadway in Well 1 Bailongshan Coal Mine adopts a planar two-part structure, the cutters are arranged in the form of single helix cutter layout, and the cutter spacing design is determined according to the discrete element simulation analysis. The scraper bucket is uniform distributed around the cutterhead, and its size is determined according to the volume of muck removal. The analysis of mechanical properties shows that the maximum overturning torque of the cutterhead is 946.53 kNm, and the overturning torque generated by the cutters is 523.28 kNm, accounting for 55.3%. The maximum horizontal and vertical unbalanced force generated by the cutters is 78.12 kN, which is only accounts for 17.2% of the vertical unbalanced force generated by the cutterhead gravity. The maximum stress of the cutterhead is 99 MPa and the maximum deformation is 0.4 mm, which is equivalent to that the overall thickness strain of the cutterhead is about 0.27‰, its performance meeting the design requirements. The cutterhead design process for gas control roadway in Well 1 of Bailongshan Coal Mine can provide reference for TBM cutterhead design of similar projects.