## 7 Discussion  
When dealing with paste fill, geotechnical studies advise using FOS > 1.4. However, prior studies have stabilized the usage of paste fill; as a result, it is advised to use the FOS on a high scale, specifically between 2.5 and 5. The primary function of internal mechanical properties in backfill is to support the wall or roof of an underground stop aperture. It is necessary to initially check the shear strength if the mining technique involves filling with the aid of the current bearing wall paste. The compressive strength (\(\sigma\)) is designed as the primary parameter and can be related to other mechanical characteristics in the paste \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Type of Paste Fill** & **Density** & **UCS (MPa)** & **Strain** & \
\begin{tabular}{c} **Shear** \\ **Strength** \\ **(MPa)** \\ \end{tabular} & **Cohesion** &
\begin{tabular}{c} **Internal** \\ **Friction** \\ **Angle (\({}^{\circ}\))** \\ \end{tabular} & **FOS** \\
6\% Cement D1 = S1 & 34,571.4 & 0.62 & 0.023 & 0.194 & 0.073 & 11.040 & 1.1 \\
6\% Cement D3 = S8 & 34,333.3 & 0.97 & 0.018 & 0.311 & 0.071 & 13.910 & 1.23 \\
6\% Cement D7 = S11 & 34,523.8 & 2.51 & 0.014 & 1.125 & 0.012 & 23.920 & 0.97 \\
6\% Cement D2 = S14 & 33,428.6 & 5.18 & 0.028 & 2.909 & 0.070 & 28.730 & 1.99 \\
8\% Cement D1 = S2 & 34,095.2 & 1.16 & 0.032 & 0.358 & 0.071 & 13.910 & 1.23 \\
8\% Cement D3 = S5 & 33,142.9 & 1.93 & 0.036 & 0.868 & 0.012 & 23.920 & 0.98 \\
8\% Cement D7 = S12 & 33,571.4 & 5.60 & 0.030 & 3.140 & 0.070 & 28.730 & 1.99 \\
8\% Cement D28 = 15 & 33,714.3 & 12.22 & 0.022 & 7.362 & 0.253 & 30.190 & 3.57 \\
10\% Cement D1 = S3 & 34,095.2 & 2.81 & 0.015 & 1.258 & 0.012 & 23.920 & 0.97 \\
10\% Cement D3 = S6 & 31,619.0 & 3.95 & 0.028 & 2.492 & 0.115 & 31.040 & 2.59 \\
10\% Cement D7 = S9 & 33,571.4 & 7.39 & 0.034 & 4.623 & 0.087 & 31.540 & 2.31 \\
10\% Cement D28 = S16 & 30,552.4 & 9.56 & 0.025 & 6.487 & 0.102 & 33.740 & 2.67 \\
12\% Cement D1 = S4 & 33,619.0 & 4.89 & 0.019 & 3.058 & 0.115 & 31.040 & 2.53 \\
12\% Cement D3 = S7 & 32,095.2 & 7.36 & 0.016 & 4.982 & 0.324 & 32.330 & 4.36 \\
12\% Cement D7 = S10 & 30,904.8 & 7.44 & 0.019 & 5.071 & 0.102 & 33.740 & 2.66 \\
12\% Cement D28 = S13 & 31,333.3 & 13.48 & 0.017 & 9.860 & 0.337 & 35.240 & 4.74 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Simulation results (FOS) with cement paste backfill. Figure 21: Slope angle of 45\({}^{\circ}\): (**a**) FOS = 4.36; (**b**) FOS = 4.74.  
fill refilling system design phase. The UCS value should be at least 5 MPa to serve as a supplementary defense mechanism; for pillar extraction, it should be closer to 1-2 MPa. In this research, the stability and strength of the cement paste fill for 3 days and 28 days, respectively, are known: for the mix cement, 6% reaches strength values of 0.97 and 5.18 MPa; for the mix cement, 8% reaches strength 1.93 and 12.22 MPa; for the mix cement, 10% reaches strength values of 3.95 and 9.56 MPa; and for the mix cement, 12% reaches strength values of 7.36 and 13.48 MPa. As can be seen in graphic 9a, the relationship between unconfined compressive strength (UCS) and curing time is a critical aspect of concrete properties; as the curing time increases, the UCS of concrete also increases. This is because a longer curing time allows for more complete hydration of the cement, resulting in stronger and more durable concrete. So, as shown in Figure 22, the value of UCS increased with a curing time of 28 days to reach the standard. With 6% cement, FOS = 1.23 and 1.99; with 8% cement, FOS = 0.98 and 3.57; with 10% cement, FOS = 2.59 and 2.67; and with cement paste filled with 12% cement, FOS = 4.36 and 4.74 (see Figure 23). This study did not investigate whether filling excavations with cemented paste backfill affects the width, height, and length of the excavations. However, it is likely that the use of cemented paste backfill would influence the dimensions of the excavations, as it provides a more stable and supportive environment compared to other filling methods.