# A Thorough Investigation of the Dynamic Properties of Granite under Cyclic Loading
## 2 Literature Review and Discussion
(2018) investigated the dynamic properties of granite under static-cyclic impact loading and found that the confining pressure had no significant effect on the dynamic elastic modulus and that the damage mode was mainly tensile damage. [PERSON] et al. (2018) investigated the effects of stress level, strain amplitude, and loading frequency on the damping ratio and damping coefficient of granite and sandstone. It was found that the effects of stress level and strain amplitude on damping ratio were more obvious than those of frequency, and the effect of frequency on damping coefficient was greater than that of strain amplitude and stress level. Table 1 summarizes the experimental designs by different researchers for acquiring the dynamic properties of rock. By reviewing the literature, we found that the experiments designed by research scholars were sufficiently complete. However, there are improvements that we can make to assess the current working state of rock based on test results. For instance, most of the scholars controlled only one, two, or three experimental variables for their rock tests, which may be insufficient for our current study. Additionally, the range of variables controlled by the scholars was rather limited. We introduced more control parameters and expanded the range of parameters in the experiment. With this improved approach, we can capture trends in the dynamic properties of specimens across multiple variables and a broader range of variables. In other words, we can obtain more comprehensive data, which is essential for us to conduct inverse analysis of the data. Simultaneously, we observed from Table 1 that most experiments conducted by researchers on granite had limited controlled parameters or a narrow range of control. Obtaining trends in the dynamic properties of granite specimens under multiple variables and a wider range of variables enables a more comprehensive study of interactions and causality among different factors. It also allows us to explore a broader range of factors influencing the dynamic properties of granite. Therefore, by utilizing our existing laboratory equipment, we defined the experimental variables as follows: loading frequency (1-20 Hz), confining pressure (5-30 MPa), dynamic stress amplitude (5-27.5 MPa), number of cycles (50 times and more), and the degree of specimen defects. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**References** & **Rock Type** & **Loading Method** & **Variables** & **Parameters** \\ \hline [PERSON] et al. (2018) & Coal & Split Hopkinson pressure bar & Confining pressures (0–20 MPa) & Failure mode \\  & & (SHPB) loading & & \\ [PERSON] et al. (2018) & Granite and red sandstone & Cyclic triaxial compression test & Confining pressures (5–25 MPa) & Dynamic shear modulus and damping ratio \\ [PERSON] et al. (2018) & Coal–rock & Dynamic impact test & Striking velocity (\(\sim\)6 m /s), & Dynamic compressive strength, elastic modulus \\ [PERSON] et al. (2018) & Sandstone & Split Hopkinson pressure bar & Temperature (\(-\)20—1 \({}^{\circ}\)C) & Strength change laws and failure patterns \\ [PERSON] et al. (2018) & Rock-like materials & Split Hopkinson pressure bar & Impact pressure (0.3–0.7 MPa), joint roughness coefficient (0–8.38) & Dynamic elastic modulus, mean dynamic compressive strength, average peak strain \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of rock properties study. This study conducted a series of cyclic loading tests on granite specimens to understand the effects of loading frequency, confining pressure, dynamic stress amplitude, and number of cycles on the dynamic properties of granite specimens, and the dynamic response model of the granite specimens was constructed. According to the degree of test completion, this paper introduces the effects of loading frequency, confining pressure, dynamic stress amplitude, and number of cycles on the dynamic characteristics of intact granite specimens and constructs the dynamic response model of granite specimens.