## 5 Conclusions  
In this paper, a series of physical and mechanical tests were carried out on sandstone with different bedding angles after high-temperature treatment, and the changes in its physical and mechanical properties were studied and analyzed. The following conclusions can be drawn:  
(1) High temperature changes the appearance characteristics of sandstone. With increasing temperature, the sandstone changed from purple-grey to red at normal temperature, the surface changed from smooth to rough, and the knocking sound changed from crisp to dull. With increasing temperature, the uniaxial compressive strength of sandstone with the same bedding angle increased first and then decreased, the longitudinal wave velocity, shear wave velocity, elastic modulus, and cohesion decreased, and the internal friction angle slightly increased. (2) For sandstone with different bedding angles, the physical and mechanical properties show obvious anisotropy. Under the same temperature conditions, the wave velocities of sandstone with bedding angles of 60\({}^{\circ}\) and 90\({}^{\circ}\) were significantly higher than those of \begin{table}
\begin{tabular}{c c c c} \hline
**Property** & **Trend Type** & **Ref.** & **Sampling Location** \\ \hline \multirow{4}{*}{\(v_{p}\)} & 1 & [PERSON] et al. [31]; & Henan Province, China \\  & 1 & [PERSON] et al. [13]; & Shandong Province, China \\  & 2 & [PERSON] et al. [32]; & Henan Province, China \\  & 3 & [PERSON] et al. [33]; & Henan Province, China \\  & & [PERSON] et al. [34]; & Cotta, Germany \\ \hline \multirow{4}{*}{\(\sigma_{c}\)} & 1 & [PERSON] et al. [33]; & Henan Province, China \\  & 1 & [PERSON] et al. [35]; & Pliezhausen, Germany \\  & 2 & [PERSON] et al. [36]; & Maulbronner, Germany \\  & 2 & [PERSON] et al. [37]; & Ordos Basin, China \\  & 3 & [PERSON] et al. [38]; & Shaanxi Province, China \\  & 3 & [PERSON] et al. [8]; & Shaanxi Province, China \\ \hline \multirow{4}{*}{\(E\)} & 1 & [PERSON] et al. [15]; & Xinjiang Uygur Autonomous \\  & 1 & [PERSON] et al. [37]; & Region, China \\  & 1 & [PERSON] et al. [38]; & Ordos Basin, China \\  & 2 & [PERSON] et al. [32]; & Dholpur, India \\  & 2 & [PERSON] et al. [32]; & Henan Province, China \\  & 2 & [PERSON] et al. [8]; & Shaanxi Province, China \\ \hline \end{tabular}
\end{table} 
Table 2: Previous research results and similar trends. sandstone with other dip angles. When the bedding angles were 30\({}^{\circ}\) and 60\({}^{\circ}\), the mechanical properties of the sandstone were better. When the bedding angle was 45\({}^{\circ}\), the mechanical properties of sandstone were the worst compared with other dip angles. After temperature treatment at 800 \({}^{\circ}\)C and above, the deterioration rate of the mechanical properties of sandstone with bedding dip angles of 60\({}^{\circ}\) and 90\({}^{\circ}\) was significantly higher than that of sandstone with other bedding dip angles, indicating that the mechanical properties of sandstone with these two bedding dip angles were greatly affected by temperature at this temperature level. (3) High temperature increases the development degree of micropores and microfractures in the sandstone bedding plane and matrix [21], thus increasing the anisotropy degree of the mechanical properties of sandstone with different bedding angles. With increasing heating temperature, the anisotropy of the uniaxial compressive strength and elastic modulus of the rock samples increased, the degree of anisotropy of cohesion decreased, and the degree of anisotropy of the internal friction angle changed little. (4) The failure mode of sandstone is closely related to bedding dip, temperature, and confining pressure. With increasing confining pressure, the cracks inside the rock sample were compressed, and the failure mode of the rock sample changed to shear failure. With increasing temperature, the rock sample gradually transitioned from brittle failure to ductile failure.