The Crushing Mode and the Optimal Penetration of Two Disc Cutters Cutting Marble under Different Confining Stress

According to the actual working condition of the full face hard rock tunnel boring machine (TBM), a 2-D discrete element model for breaking marble by two TBM disc cutters is established, it simulates the whole progress of cracks production and propagation under different confining stress and penetration; based on CSM prediction model, forces of two cutters and specific energy consumptions are calculated to determine the best penetration. The simulating result shows that there are three kinds of breaking modes of marble under different confining stress and penetration; As well as the trend that specific energy consumption decrease first and then increase with the penetration increases, and there is optimal penetration to make specific energy consumption the lowest each confining stress. The optimal penetration and the lowest specific energy consumption are determined when confining stress range from 0 to 40MPa according to the simulation results.