# Numerical Simulation of Rock-Breaking Mechanism by Spherical Tooth Impact in Granite Formation  
[PERSON]  
1 School of Engineering and Technology, China University of Geosciences, Beijing 100083, China; [EMAIL_ADDRESS] (J.  
sufficient space and passage for trapped personnel. The button layout design of the DTH hammer drill bit is a critical factor in improving rock-breaking efficiency and extending the service life of the drill bit [4]. Therefore, research on the rock-breaking mechanism of tungsten carbide buttons, the optimization of drilling parameters, and the rational design of button distribution play a vital role in enhancing drilling efficiency. Numerous studies have explored the rock-breaking mechanism of tungsten carbide buttons via experimental and numerical approaches. Previous studies on rock-breaking mechanisms primarily focused on single-button performance. For instance, [PERSON] et al. [5] analyzed the effects of loading and indenter spacing on rock damage using numerical simulations and experiments. They compared two measurement methods and concluded that rock indentation damage is primarily caused by the development of tensile strain. [PERSON] et al. [6] confirmed that the compaction zone under the indenter is limited. Rock failure only occurs when the circumferential stress exceeds the tensile strength of the rock. [PERSON] et al. [7] studied the compression failure mechanism of sandstone by recording force-displacement curves during the indentation process. They employed digital image correlation (DIC), a non-destructive optical technique, to measure the full-field displacements on the sandstone surface. [PERSON] et al. [8] explored the impact fracture mechanism of rocks under low-energy conditions through single-head impact experiments. Using 3D scanning technology, they obtained precise parameters of the impact craters. [PERSON] et al. [9] conducted quasi-static indentation and dynamic impact tests using conical and spherical drill bits on sandstone, granite, and basalt. They examined the relationship between contact force and displacement. [PERSON] et al. [10] demonstrated through numerical methods that dynamic loading and indenter spacing play a critical role in the rock-breaking process with dual indenters, providing a basis for optimizing rock-breaking efficiency. [PERSON] et al. [11] proposed the plastic energy consumption ratio as an indicator to evaluate the efficiency of indenters breaking hard rocks. Their results showed that the lower the plastic energy consumption ratio, the higher the efficiency of rock indentation failure. [PERSON] [12] employed non-destructive techniques such as acoustic emission and electronic speckle interferometry to study the indentation process of rocks using wedge-shaped tools. They found that the geometric characteristics of the wedge-shaped tools and the mechanical properties of the rock significantly affect the indentation pressure and damage zone size. Additionally, under certain lateral confinement conditions, the rock failure mode transitions from brittle to plastic behavior. A wealth of research has focused on the energy transfer efficiency and rock-breaking mechanisms of impact drilling. [PERSON] et al. [13] developed a mathematical model for pneumatic rotary drilling and analyzed the impact energy transfer in pneumatic top-hammer rock drilling. [PERSON] et al. [14; 15] investigated the effect of waveforms on the energy transfer efficiency of impact drilling in both integrated drill rods and detachable drill bits using a one-dimensional stress wave propagation model. [PERSON] et al. [16] established a three-dimensional impact system model, considering the strong nonlinearity during the impact process, to study the energy transfer efficiency of impact drills. In further studies, [PERSON] et al. [17; 18] explored the energy transfer efficiency and rock damage caused by multi-button drill bits in axial-torsional coupled impact drilling.