## 2 Ring Specimen Processing and Its Physical Parameters
### Basic Physical Properties  
The size and basic physical parameters of the sandstone ring specimens in their natural state and after 10 dry-wet cycles are shown in Table 1.  
It can be seen in Table 1 that the mass of the sandstone ring specimen decreased and the volume increased after 10 dry-wet cycles. The mass loss rate, volume expansion rate, and density reduction rate of the specimen changed with the change in the inner diameter, as shown in Figure 3.  
It can be seen in Figure 3 that after the dry-wet circulation of the sandstone ring specimen, the mass loss rate of the specimen increased from 2.27% to 2.63% with the increase in the inner diameter of the ring specimen. The volume expansion rate of the specimen did not change considerably when the inner diameter was 0-15 mm, with it essentially measuring between 3.75% and 4.25%; when the inner diameter was 15 mm-25 mm, the volume expansion rate of the specimen showed a downward trend, and the volume expansion rate was 3.00% when the inner diameter was 25 mm. The density of the specimen showed an increasing trend with the increase in the inner diameter of the specimen, and the trend was similar to the volume expansion rate. The density reduction rate did not change considerably with the inner diameter of 0-15 mm, with it ranging from 5.95% to \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Inside** \\ **Diameter** \\ **/mm** \\ \end{tabular} } & \multirow{2}{*}{**Specimen**} & \multicolumn{4}{c}{**Raw State**} & \multicolumn{4}{c}{**Dry and Wet Cycle (10 th Time)**} \\ \cline{3-10}  & & & **Outside** & **Inside** & **Diameter** & **Quality** & **Height** & **Diameter** & **Diameter** & **Quality** \\  & & **/mm** & **/mm** & **/mm** & **/g** & **/mm** & **/mm** & **/mm** & **/mm** & **/g** \\ \hline \multirow{3}{*}{0} & PJ06-01 & 25.6 & 50.3 & 0.0 & 125.59 & 25.8 & 50.6 & 0.0 & 122.76 \\  & PJ06-02 & 25.2 & 50.3 & 0.0 & 125.71 & 25.7 & 50.8 & 0.0 & 122.87 \\  & PJ06-03 & 25.2 & 50.2 & 0.0 & 125.20 & 25.7 & 50.7 & 0.0 & 122.37 \\ \hline \multirow{3}{*}{5} & PJ06-04 & 25.4 & 50.3 & 5.1 & 125.88 & 25.9 & 50.8 & 5.0 & 123.01 \\  & PJ06-05 & 25.6 & 50.1 & 5.0 & 123.47 & 26.0 & 50.7 & 4.9 & 120.65 \\  & PJ06-06 & 25.2 & 50.3 & 5.0 & 123.86 & 25.8 & 50.7 & 4.9 & 121.03 \\ \hline \multirow{3}{*}{10} & PJ06-07 & 25.3 & 50.2 & 10.1 & 119.19 & 25.5 & 50.8 & 9.9 & 116.41 \\  & PJ06-08 & 25.4 & 50.3 & 9.9 & 119.61 & 25.8 & 50.7 & 9.7 & 116.81 \\  & PJ06-09 & 25.4 & 50.1 & 10.0 & 119.68 & 25.9 & 50.5 & 9.7 & 116.88 \\ \hline \multirow{3}{*}{15} & PJ06-10 & 25.7 & 50.3 & 15.1 & 115.62 & 26.2 & 50.7 & 14.8 & 112.83 \\  & PJ06-11 & 25.7 & 50.2 & 15.1 & 116.42 & 26.2 & 50.5 & 14.7 & 113.62 \\  & PJ06-12 & 25.1 & 50.3 & 15.0 & 113.65 & 25.5 & 50.7 & 14.7 & 110.90 \\ \hline \multirow{3}{*}{20} & PJ06-13 & 25.3 & 50.3 & 20.1 & 104.60 & 25.7 & 50.7 & 19.7 & 101.96 \\  & PJ06-14 & 25.4 & 50.3 & 19.9 & 104.88 & 25.7 & 50.6 & 19.5 & 102.22 \\ \cline{1-1}  & PJ06-15 & 25.4 & 50.0 & 20.1 & 103.99 & 25.8 & 50.4 & 19.7 & 101.36 \\ \hline \multirow{3}{*}{25} & PJ06-16 & 25.5 & 50.2 & 25.1 & 95.08 & 25.7 & 50.7 & 24.9 & 92.56 \\ \cline{1-1}  & PJ06-17 & 25.4 & 50.2 & 25.1 & 94.21 & 25.7 & 50.5 & 24.8 & 91.72 \\ \cline{1-1}  & PJ06-18 & 25.5 & 50.3 & 25.1 & 94.16 & 25.8 & 50.7 & 24.9 & 91.66 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Basic physical parameters of the sandstone ring specimens before and after dry and wet cycling. Figure 2: Sample diagram after dry and wet cycling. 6.16%. The density reduction rate decreased significantly from 6.15% to 5.47% with an inner diameter of 15 mm\(-\)25 mm. As the inner diameter of the ring specimen increased, the wall thickness decreased, and the contact area between the specimen and water increased during the dry-wet cycle. It was found that the water in the specimen evaporated after the first dry-wet cycle.