# Numerical Simulation on Dynamic Response of Drilling Parameters in Loaded Rock Mass
## 5 Conclusions  
Aiming at the problem of in situ identification of rock mechanical parameters of coal and rock mass in mine, this paper takes the drilling pressure relief project of the deep roadway in the Guotun Coal Mine as the background and adopts the research paradigm of a multi-dimensional verification of numerical simulation and a field test to systematically reveal the coupling mechanism of confining pressure-lithology-drilling parameters. According to the geological data of the deep roadway in the Guotun Coal Mine, the material parameters of different lithologies (coal, mudstone, sandy mudstone, and siltstone) are set, and the stress environment under different confining pressure conditions of 0-15 MPa is simulated. Through the simulation experiment of mesoscopic damage drilling based on the ABAQUS platform, the dynamic response law between different lithologies (coal, mudstone, sandy mudstone, and siltstone), confining pressure conditions (0-15 MPa), and drilling parameters (drilling rate, thrust, and torque) is compared and analyzed. The aim is to provide a theoretical basis for on-site identification of rock mechanical parameters. In this paper, the drilling parameters are analyzed and discussed based on numerical simulation combined with on-site drilling pressure relief. The main findings are as follows:  
1. At the same thrust-revolution speed level, the higher the strength of the rock, the greater the torque required for the drilling process and the slower the drilling rate. Figure 20: Stress cloud diagram of drilling for 1 s under different confining pressures. (**a**) 0 MPa; (**b**) 5 MPa; (**c**) 10 MPa; (**d**) 15 MPa. The average drilling rate of the four kinds of rock drilling is coal > mudstone > sandy mudstone > siltstone;
2. When the thrust is constant, with the increase in revolution speed, the drilling rate of coal, mudstone, sandy mudstone, and siltstone is approximately proportional to the linear increase, and the torque shows a negative correlation trend with the increase in the drilling rate. When the revolution speed is constant, with the increase in thrust, the drilling rate and torque of all kinds of rocks will gradually increase accordingly, showing a significant positive correlation trend;
3. With the increase in the confining pressure of the specimen, the average value of the torque increases gradually, and the average value of the drilling rate decreases gradually. There is an approximate linear negative correlation between drilling rate and rock confining pressure, and an approximate linear positive correlation between torque and rock confining pressure;
4. In this paper, the variation in parameters while drilling under different influence conditions is preliminarily studied. At the same time, there are also some shortcomings. For example, only four rock samples of coal, mudstone, sandy mudstone, and siltstone are selected for research, and other common rock types are not involved. The limited selection of rock types limits the universality of the research results. Therefore, future research can consider further increasing the types of rock samples (such as limestone, shale, etc.) and discuss the response characteristics of drilling parameters under complex geological conditions to further improve and expand the experimental results. Conceptualization, Methodology, Writing--review and editing: [PERSON]; Writing--original draft, Visualization: [PERSON] and Y.Z. ; Conceptualization, Methodology, Funding acquisition, Supervision: D.G. ; Investigation, Methodology: J.L. and H.L. All authors have read and agreed to the published version of the manuscript. This research was funded by the Fundamental Research Funds for the Central Universities (No. 3142023005), the Science and Technology Support Project of Langfang (No. 2023013149), the National Natural Science Foundation of China (No. 52204101), and the Natural Science Foundation of Shandong Province (No. ZR2022 QE137). Not applicable.