Numerical Study on the Influence of the Width of the SBM Disc Cutter on Rock Breaking

The study of the rock-breaking pattern of shaft boring machine (SBM) cutters is the basis for cutter design. In order to reveal the influence of the cutter blade width on the rock-breaking effect, this study established a discrete-continuous coupled rock mass numerical model. By setting different blade widths and types, the variation patterns of cutter forces, rock-breaking area, and specific energy with the blade width were revealed. The influence of the blade type on the breaking coefficient was further quantified according to the fractal dimension. The results show that under the cutting action, the rock mass can be divided into dense core, fractured zone, and elastic deformation zone, with the fractured zones mainly located on the lower side of the cutter's central axis. As the width of the cutter increases, the cutter penetration force and side force increase linearly with the increase in blade width, the breaking area increases and then tends to remain constant, the specific energy decreases first and then increases, and the rock fragmentation factor increases linearly. After scaling the width of the flat blade up to 18 mm and the arc blade to 24 mm, further increase in the blade width does not improve the breaking efficiency but only results in a smaller slag granularity.