Numerical Simulation Analysis of Different Excavation Parameters for TBM 3D Disc Cutters Based on the Discrete Element Method  
[PERSON]  
1 Xinjiang Water Conservancy and Hydropower Survey Design Institute Co., Ltd., Urumqi 830000, China; [EMAIL_ADDRESS] (F.L.) [PERSON]  
2 Xinjiang Shuita Construction Group Co., Ltd., Urumqi 830000, China 2  
[PERSON]  
1 Xinjiang Water Conservancy and Hydropower Survey Design Institute Co., Ltd., Urumqi 830000, China; [EMAIL_ADDRESS] (F.L.) [PERSON]  
3 Faculty of Engineering, China University of Geosciences, Wuhan 430074, China 3* *  
surrounding rock and plastic zone expansion at the arch bottom within the fault zone often increase, leading to potential cutter head sinking and \"bottom bulging\" of the surrounding rock. These conditions create complex force dynamics for TBM operations in fault zones. The improper selection of disc-cutter types or designs under such conditions can reduce rock-breaking efficiency, delay construction schedules, and even pose safety risks. To minimize unnecessary cutter wear and improve efficiency, researchers have explored various optimization strategies for cutter layouts, rock-breaking mechanisms, and tunneling parameters. [PERSON] et al. [5] and [PERSON] et al. [6] developed calculation models for key parameters, such as cutter layout and design, based on geological conditions and structural parameters, introducing a geological adaptive design method for TBM disc cutters. [PERSON] et al. [7] investigated the crack initiation life of TBM disc cutters under different geological conditions and developed a geological matching calculation model based on crack initiation. [PERSON] et al. [8] analyzed the compound rock-breaking characteristics of impact disc cutters, derived cutting load equations, and established models for rock fragmentation volumes. [PERSON] et al. [9] investigated the wedge-induced rock-breaking performance of disc cutters on prefabricated fractured rocks, identifying three stages in the rock-breaking process: the compressive stage, the stress accumulation stage, and the fragmentation stage, based on cutter load fluctuations and acoustic emission characteristics. [PERSON] et al. [10] conducted experiments and simulations to compare the rock-breaking mechanisms of TBM disc cutters under traditional and free-face conditions, concluding that free-face conditions reduce rock-breaking force and improve efficiency. Theoretical analysis has limited applicability, and laboratory experiments are often time-consuming, costly, and inadequate for investigating crack development patterns. In contrast, numerical simulation techniques offer a cost-effective alternative for simulating the rock-breaking process, yielding promising results. [PERSON] et al. [11] developed a finite element model for disc-cutter rock breaking using LS-DYNA, analyzing rolling processes and rock fracture patterns, and identified three fracture modes: forward slip, no slip, and backward slip. [PERSON] et al. [12], using PFC 6.0 simulation software to explore rock-breaking patterns for various cutter configurations (single edge, double edge, and triple edge), discovering that increasing the number of cutters reduced the vertical force and torque per cutter. [PERSON] et al. [13] examined factors affecting TBM disc-cutter efficiency in deep rock excavations, including confining pressure, penetration, cutter spacing, and revolution speed. Their results showed that cutter spacing had the most significant impact on rock-breaking specific energy. [PERSON] et al. [14] used Matrix Discrete Element Method (MatDEM 2.0) software to investigate the rock-breaking mechanism of disk cutters at soil-rock interfaces. Comparative analysis has demonstrated that a numerical simulation can have significant advantages in exploring disc-cutter rock breaking, leading to its growing use by researchers in related studies [15; 16; 17]. Figure 1 illustrates a TBM cutting head, which features numerous disc cutters.