## 7 Conclusions  
1. Three-dimensional engraving technology can effectively fabricate joint specimens that are applicable to laboratory tests. The joint specimen fabricated by this method has the morphological characteristics of being highly consistent with the prototype, which is available to analyze the shear properties and morphological characteristics of the rock joint with different joint wall strengths made by various rock and rock-like materials. 2. The shear curve of the numerical simulation is basically consistent with the test curve, which verifies the accuracy of the CY constitutive model in simulating progressive failure of discontinuities possessing different joint wall strengths. Integrating the shear stress contour of the numerical simulation and the test results to analyze, the damage area in the shearing process of discontinuities possessing different joint wall strengths is mainly concentrated on the asperity facing the shear direction. The shear wear and cutting destruction of discontinuities possessing different joint wall strengths are mainly distributed in the soft rock. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Normal Stress (MPa)**} & \multicolumn{5}{c}{**The Identifier of Specimens**} \\ \cline{2-6}  & **SSR2** & **SCR2** & **CCR2** & **GCR2** & **GGR2** \\ \hline
0.5 & 0.468 & 0.419 & 0.398 & 0.397 & 0.506 \\
1 & 0.418 & 0.391 & 0.355 & 0.367 & 0.471 \\
2 & 0.376 & 0.353 & 0.311 & 0.338 & 0.398 \\
3 & 0.337 & 0.317 & 0.265 & 0.289 & 0.362 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Dilation values of rock–rock discontinuities and rock–mortar discontinuities (mm). Figure 18: Dilation curves of SSR2, SCR2 and CCR2 under normal stresses are (**a**) 0.5 MPa, (**b**) 1.0 MPa, (**c**) 2.0 MPa and (**d**) 3.0 MPa. 3. The dilation displacement of discontinuities possessing different joint wall compressive strengths decreases with the increase in normal stress. Due to the cooperative effect of roughness and undulation, the dilation displacement of discontinuities possessing different joint wall strengths with JRC of 10.8 is the largest, discontinuities possessing different joint wall strengths with JRC of 18.7 is second and discontinuities possessing different joint wall strengths with JRC of 2.8 is the smallest. The embedding effect of asperities is enhanced and the climbing dilation effect is weakened as a result of the great difference in joint wall strength on both sides of granite-mortar discontinuities. Therefore, the dilation displacement of granite-mortar discontinuities is smaller compared with sandstone-mortar discontinuities. 4. On basis of the numerical results, the peak shear strength and residual shear strength of discontinuities possessing different joint wall strengths are between those of discontinuities possessing identical joint wall strengths composed of hard rock and discontinuities possessing identical joint wall strengths composed of soft rock. Meanwhile, the dilation displacement of discontinuities possessing different joint wall strengths is also between discontinuities possessing identical joint wall strengths composed of hard rock and discontinuities possessing identical joint wall strengths composed of soft rock. All authors made substantial contributions to the conception and design of the study. X.Z. : conceptualization, methodology, funding acquisition and writing--review & editing. S.O. : investigation, data curation and writing original draft. C.F. : methodology and writing--review & editing. L.Y. : data curation and writing--review & editing. D.L. : supervision, methodology and writing--review & editing. All authors have read and agreed to the published version of the manuscript. Open Foundation of Jiangxi Hydraulic Safety Engineering Technology Research Center, Jiangxi Academy of Water Science and Engineering (Grant No. 2022 SKSG06), Young Elite Scientists Sponsorship Program by JXAST (Grant No. 2023 QT06), Jiangxi Provincial Natural Science Foundation for Distinguished Young Scholars (Grant No.