## 5 Conclusions  
The effects of joint roughness and inclination on the dynamic mechanical properties, stress wave propagation characteristics, and failure mode of jointed rocks have been investigated by conducting impact tests for prefabricated serrated joint cement mortar specimens. The conclusions are drawn as follows.  
1. Both joint roughness and inclination have certain effects on the peak stress of the jointed specimen. The peak stress initially decreases then increases with the increase of the joint inclination angle, namely a V-shape variation. The influence of JRC on the peak stress of jointed specimens is negligible at inclination angles of 0\({}^{\circ}\) or 90\({}^{\circ}\). The peak stress gradually increases with JRC increasing when the joint inclination angle is in the range of 30\({}^{\circ}\) to 60\({}^{\circ}\). Jointed specimens exhibit the lowest peak stress at an inclination angle of 45\({}^{\circ}\) and JRC of 0.
2. The existence of joint inclination and roughness affect the stress wave propagation through the jointed specimen. When the JRC increases from 0 to 20, the reflection of stress waves on the joints gradually increases, and the transmission decreases for the joint inclination angles of 0\({}^{\circ}\) and 90\({}^{\circ}\). On the contrary, when the joint inclination angle is in the range of 30\({}^{\circ}\) to 60\({}^{\circ}\), the reflection of stress waves on the joints gradually decreases, and the transmission gradually increases with JRC increasing from 0 to 20.
3. The effect of JRC on the failure mode under impact load is significant. Jointed rocks exhibit three typical failure modes, namely splitting tensile failure parallel to the joint surface, shear slip failure along the joint surface, and compound failure of splitting tensile and shear.
4. Joint roughness and inclination influence the energy transfer through jointed rocks. With the joint inclination angle increasing, reflected energy coefficient initially increases then decreases, while the transmitted energy coefficient initially decreases then increases. At joint inclination angles of 0\({}^{\circ}\) or 90\({}^{\circ}\), the reflected energy coefficient increases with the increase of JRC from 0 to 20, while the transmitted energy decreases. However, when joint inclination angles are in the range of 30\({}^{\circ}\) to 60\({}^{\circ}\), the reflected energy coefficient gradually decreases with JRC increasing, while the transmitted energy coefficient gradually increases.  
Conceptualization, P.Y.; Software, Q.Z.; Validation, A.L.; Formal analysis, A.L.; Data curation, C.C.; Writing--original draft, A.L.; Writing--review & editing, P.Y. All authors have read and agreed to the published version of the manuscript.  
This work was funded by Anhui Provincial Natural Science Foundation (No. 2108085 ME156 and No. 1808085 QE148), China Postdoctoral Science Foundation (No. 2018M642504), The University Synergy Innovation Program of Anhui Province (No. GXXT-2022-020), and Natural Science Research Project of Colleges and Universities in Anhui Province (No. KJ2017A097).  
The data used to support the findings of this study are available from the corresponding author upon request.  
The authors declare no conflict of interest.