STUDY ON THE ROCK-BREAKING FORCES OF TBM DISC CUTTERS WITH UNEVEN WEAR

The disc cutter rock-breaking force of full face rock tunnel boring machines (TBMs) has long been a key topic in tunneling mechanics. However, current studies mainly focus on laboratory cutting tests and numerical simulations, resulting in predominantly empirical models that are insufficient to accurately reflect the influence of uneven cutter wear on rock-breaking forces in practical engineering. In this study, based on plasticity theory, a combined approach of numerical simulation and theoretical analysis is employed to reveal the “plastic-brittle” behavior of rock under disc cutter action. Theoretical formulations for the normal force and rolling force of worn disc cutters are derived, with a maximum validation error less than 4%. A numerical model of rock cutting with unevenly worn disc cutters is established using ABAQUS, enabling a comparative investigation of rock-breaking forces and specific energy. The cutting process under uneven wear is, for the first time, classified into three stages: acceptable, transitional, and unacceptable non-synergistic cutting. A predictive model for specific energy under different installation radii is developed, with a maximum error of 6.5%. Furthermore, a performance index \eta is proposed to quantify the degree of non-synergism in rock breaking induced by uneven wear. The results show that rock-breaking forces increase with wear amount, while the specific energy increases with both wear and installation radius, exhibiting distinct interval characteristics. This study provides theoretical support and practical reference for cutter replacement decisions and the prediction of rock-breaking performance under uneven wear conditions in TBM operations.