Experimental and numerical investigations on the force characteristics of cutter in different regions of the TBM cutterhead

Abstract

The cutters on the cutterhead of a tunnel boring machine (TBM) are usually divided into center cutters, face cutters, and gage cutters, and have significantly different force characteristics. In this study, the authors conduct a series of full-scale cutter rotary cutting tests to compare the differences in the cutter force, the morphology of rock ships, and the efficiency of rock breaking. The results indicate that with increasing cutter spacing, the influence exerted by the cutters on one another in terms of their performance at breaking rocks decreases and their normal force gradually increases, while the rolling force of the cutters is less influenced by the spacing between them. The ratio of the normal force to the rolling force of the gage cutter is less than that of the face cutter, indicating a lower efficiency of breaking rock of the gage cutter. The ratio of rock chips with larger size (>50 mm) and smaller size (<10 mm) gradually decreases while that of rock chips with medium size (about 10–50 mm) gradually increases with increasing installation angle, such that the distribution of the particle size becomes more uniform. Excessive or insufficient penetration rate (PR) will increase the proportion of small rock chips, and a moderate PR will produce rock chips with a larger characteristic size and a more uniform size distribution. Then, a three-dimensional rock-breaking model by all cutters of actual TBM cutterhead is established based on the particle flow method. The results of the simulations indicate that the force on the inner ring of the center cutter is greater than that on the outer ring, and an increase in the installation radius weakens the load difference between the two rings. The normal and rolling forces of face cutters gradually increase, while their side force first increases and then decreases. The side force of the gage cutter significantly increases with the installation angle.