Numerical analysis for rock cutting force prediction in the tunnel boring process

Abstract Study of rock cutting force prediction is of great significance for improving the efficiency of rock breaking and optimizing the tunnel boring process. A new prediction model named RCC (the Roxborough Model and the CSM Model and the Colorado School of Mines’ Data Integration) model is proposed to predict vertical, rolling and lateral forces acting on the disc cutter based on the theoretical model developed by Roxborough and Phillips (1975) (Roxborough model) and the theoretical model developed by Rostami (1997) (CSM model). The suggested model is based on the improvement that the shape of extrusion surface is reasonably assumed to be trapezoid and the arc segment at the edge of the cutter is reasonably simplified to a straight-line segment. Results of the full-scale linear cutting experiments by the Colorado School of Mines are used to validate the accuracy and reliability of the suggested model, some additional calculation results from the linear cutting prediction formula developed by Ozdemir et al. (1978) (Linear Cutting model) and the CSM model are also used in this purpose. The results indicate that the formulas for calculating vertical force and rolling force presented in this paper are more accurate than the Linear Cutting model and the CSM model. Although the calculation results of the lateral rock breaking force conforms to the variation law of lateral rock breaking force with the penetration and cutter spacing, they are smaller than the experimental data. Finally, through theoretical analysis of the suggested RCC model and numerical simulation by using ANSYS/LS-DYNA, the rationality of the simplified disc cutter used in the RCC model is verified and the influence of penetration depth on the rock cutting force is obtained, which provides a theoretical reference for the study of rock breaking mechanism and optimization of tunneling process.