## 1 Introduction  
As traditional energy sources, such as oil and coal, in the shallow parts of the Earth are gradually depleted, mining deep resources is a strategic, scientific, and technological issue that we must address [1, 2, 3]. Deep rock formations in extreme environments are characterized by complex working conditions, various structures, high hardness, and high resistance to compression. Moreover, traditional drilling and coring techniques encounter challenges related to poor core fidelity and low rock-breaking efficiency [4, 5]. New fidelity drilling and coring techniques aim to obtain complete rock samples, explore in situ stratigraphic information, investigate the in situ characteristics and physical and mechanical properties, and analyze the rock mechanical behavior of deep rocks within high-hardness rock formations at different depths exceeding 1000 m [6]. Core fidelity refers to the accuracy and integrity of the core samples obtained during drilling or coring operations. It measures how well the extracted core samples retain the original characteristics of the subsurface formations. Minimizing the stress impact on the core samples during the drilling process is essential, as residual stresses within the core can influence its physical and mechanical properties. Furthermore, maintaining residual stresses within the linear elastic range after drilling and cutting the core ensures the fidelity of the core samples. As the drilling depth increases, the pressure required to break the core during bit cutting also rises, thus presenting a more significant challenge in achieving core fidelity. By using appropriate coring bits and minimizing disturbances or damage to the core during extraction, fidelity coring enables researchers to obtain samples that accurately reflect the characteristics of subsurface rock formations [7]. The structural parameters of the drill bit used in this process directly affect the magnitude and distribution of stresses within the core, thereby impacting the fidelity of coring performance. Therefore, selecting appropriate drill bit structural parameters can optimize the breaking effect, reduce stress impact on the core, and enhance core fidelity performance. Conducting in-depth research on the influence of core drilling bit parameters on fidelity coring performance holds significant importance for comprehensively understanding the drilling and cutting mechanisms of core drilling bits. In the field of fidelity coring, [PERSON] et al., introduced the concept of in situ insulation and pressure-holding coring principles and techniques. They developed a coring device to achieve fidelity coring under in situ pressure and temperature conditions, allowing for the characterization of deep rocks at various depths [8]. [PERSON] et al., proposed a coring principle and technique for in situ pressure-holding coring in deep coal mines. They also developed an in situ pressure controller to ensure high coring efficiency and stable pressure holding [9; 10]. [PERSON] et al., addressed the limitations of insulated coring and proposed an innovative design of an active insulation system for accurate temperature retention in in situ fidelity coring of deep rock formations [11]. [PERSON] et al., developed an in situ fidelity coring system and designed pressure controllers for different coring formations to minimize disturbance during drilling [12; 13]. In the past, limited research has been conducted to develop fidelity coring tools. Most research in the field of fidelity has primarily concentrated on the temperature and pressure control of cores that have already been drilled by cores. Since a drill bit's cutting teeth directly contacts the core, ensuring fidelity control during the drilling process is crucial. However, very few previous research studies have explored the relationship between the structural parameters of drill bits and fidelity performance.