The multi-stage rock fragmentation load prediction model of tunnel boring machine cutter group based on dense core theory

Disk cutter is a working part of the tunnel boring machine (TBM), which is directly in contact with the rock, bearing a strong impact load and vibration, so the structure is very easy to have damage and failure. The accurate prediction of the cutter group load is the key to structure design of cutters. However, the existing prediction model cannot reflect the multi-peak characteristics in the breaking process. In this paper, a theoretical prediction model of the disk cutter group of a TBM is presented. The model is based on dense core theory, rock characteristics, the types of disk cutters, the layout and structural parameters of the cutters, tunneling parameters, and the compound multi-stage space breaking load. A linear disk cutting test was carried out to verify the accuracy of the theoretical prediction model. The model reflects the multi-stage peak value and segmented step of the cutter load, and based on the theoretical prediction model, the effects of the cutter installation radius and the tilt angle of the gauge cutters on the load are analyzed. The results presented provide a theoretical basis for the prediction of the cutter load and the arrangement of the cutters in a TBM.