## 5 Conclusions  
In conclusion, we have developed a novel nonlinear creep model that considers temperature-pH damage to address the issue that the Nishihara creep model curve for sandstone under the coupled effect of chemical corrosion and temperature is poorly fitted with actual creep test data.  
1. Based on the Nishihara creep model, the viscoelastic elements in the Nishihara model are replaced with viscoelastic elements incorporating the temperature and pH influence factors, and the new viscoelastic element is discovered to accurately describe the influence of temperature and pH on rock creep characteristics. The viscoplastic elements in the Nishihara model are replaced with nonlinear viscoplastic elements, and the nonlinear viscoplastic element is discovered to accurately describe the accelerated creep stage of the rock mass. Further, a nonlinear creep model under the coupled effect of chemical corrosion and temperature is established after two revisions to the Nishihara creep model, and it can well describe the influence of temperature and pH on the rock's creep characteristics.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Axial** & \(\mathbf{E_{1}}\) & \(\mathbf{E_{2}}\) & \(\mathbf{\eta_{1}}\) & \(\mathbf{\eta_{2}}\) & \(\mathbf{\alpha}\) & \(\mathbf{n}\) & **The Fitting Degree** \\
**Pressure/MPa** & **/GPa** & **/GPa** & **(\(\times\)10\({}^{3}\) GPa-h)** & **(\(\times\)10\({}^{3}\) GPa-h)** & **(\(\times\)10\({}^{3}\) GPa-h)** & **(\(\times\)10\({}^{3}\) GPa-h)** & **(\(\times\)10\({}^{3}\) GPa-h)** & **(\(\times\)10\({}^{3}\) GPa-h)** \\ \hline
8 & 1.294 & 3.146 & \(\backslash\) & 1.520 & 0.212 & \(\backslash\) & 0.95 \\
16 & 1.352 & 4.524 & 0.0001 & 2.458 & 0.102 & 10.869 & 0.92 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Model parameters.  
Figure 7: Comparison of creep test results with the new model: (**a**) Comparison of creep models for \(\sigma<\sigma_{s}\); (**b**) Comparison of creep models for \(\sigma>\sigma_{s}\).  
In this study, the creep test of sandstone specimens is conducted under the coupled effect of chemical corrosion and temperature, and a portion of the sandstone creep test data is compared with the creep curve of the nonlinear creep model considering temperature-pH damage. The comparison results show that the creep curve of the nonlinear creep model established in this study fits well with the sandstone creep test data. The validity of the newly developed nonlinear creep model has been established, and it can accurately describe the effects of temperature and pH on sandstone creep characteristics.  
The manuscript was prepared through the contribution of all authors. Conceptualization, X.X. and Y.W.; methodology, Y.W.; software, G.N.; validation, Y.Z.; data curation, D.C.; writing--original draft preparation, X.X.; writing--review and editing, G.N.; supervision, S.Z.; project administration, Y.W. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Natural Science Foundation of China (42307236; 12302264), the Natural Science Foundation of Shandong Province (ZR2023 QE001), the Research Fund of the State Key Laboratory of Coal Resources and Safe Mining (SKLCRSM19 KF015), the Research Fund of the Key Laboratory of Mine Disaster Prevention and Control of the Ministry of Education (MDPC201915), the Qingdao Natural Science Foundation (24-4-4-zri)-80-jch).  
Not applicable.  
The data used to support the findings of this study are available from the corresponding author upon request.  
The authors declare that there are no conflicts of interest regarding the publication of this article.