## 2 Theory of Slug Test on Determining Permeability Coefficient of Anisotropic Fractured Rock Mass
### Comparative Analysis of the Slug Tests and Water Pressure Tests Results  
According to the assumption of the rock mass equivalent permeability coefficient, it is assumed that heterogeneous rock strata are mostly composed of many mutually alternating layered rock strata with different permeability. The thickness of each single layer is much smaller than its extension length. When the permeability coefficient \(K_{i}\) and thickness \(M_{i}\) of each layer are known, the equivalent permeability coefficient in the direction parallel to the layer \(K_{p}\) can be calculated by the following equation:  
\[K_{p}=\frac{\sum_{i=1}^{n}K_{i}M_{i}}{\sum_{i=1}^{n}M_{i}} \tag{18}\]  
Therefore, in order to compare the results of the water pressure test and slug test in the same test section, it is necessary to obtain the equivalent permeability coefficient of the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Group**} & \multirow{2}{*}{**Test No.**} & **Initial Water** & & & **Fracture** \\  & & **Level** & & **Test Section** & **Equivalent** \\
**(Corresponding Footage)** & & **Difference** & **Position (m)** & **Permeability** \\  & & **(cm)** & & & **Coefficient (cm/s)** \\ \hline Group No. 1 (Footage No. 2) & HD-01 & 2.5 & Pneumatic & 0.5–0.89 & \(1.06\times 10^{-4}\) \\ Group No. 2 (Footage No. 3) & HD-02 & 3.4 & Pneumatic & 0.5–1.3 & \(1.03\times 10^{-4}\) \\ Group No. 3 (Footage No. 4) & HD-03 & 1.2 & Pneumatic & 0.5–1.8 & \(1.19\times 10^{-4}\) \\ Group No. 4 (Footage No. 5) & HD-04-01 & 0.8 & Pneumatic & 0.5–2.43 & \(1.03\times 10^{-4}\) \\ Group No. 5 (Footage No. 6) & HD-05-01 & 1.8 & Pneumatic & 0.5–3.16 & \(7.75\times 10^{-5}\) \\  & HD-06-01 & 9.3 & Lifting & 0.5–4.76 & \(1.94\times 10^{-5}\) \\ Group No. 6 (Footage No. 7) & HD-06-02 & 1.9 & Pneumatic & 0.5–4.76 & \(5.62\times 10^{-5}\) \\  & HD-06-03 & 7.8 & Lifting & 0.5–4.76 & \(2.83\times 10^{-5}\) \\ Group No. 7 (Footage No. 8) & HD-07-01 & 8.4 & Lifting & 0.5–5.83 & \(1.15\times 10^{-5}\) \\ Group No. 7 (Footage No. 8) & HD-07-02 & 3.1 & Pneumatic & 0.5–5.83 & \(4.95\times 10^{-5}\) \\ Group No. 8 (Footage No. 9) & HD-08-01 & 8.5 & Lifting & 0.5–7.72 & \(8.47\times 10^{-6}\) \\  & HD-08-02 & 3.1 & Pneumatic & 0.5–7.72 & \(3.82\times 10^{-5}\) \\ Group No. 9 (Footage No. 10) & HD-09-01 & 2.9 & Pneumatic & 0.5–8.99 & \(3.4\times 10^{-5}\) \\  & HD-09-02 & 8.1 & Lifting & 0.5–8.99 & \(6.46\times 10^{-6}\) \\  & HD-10-01 & 3.0 & Pneumatic & 0.5–10.12 & \(3.01\times 10^{-5}\) \\ Group No. 10 (Footage No. 11) & HD-10-02 & 8.3 & Lifting & 0.5–10.12 & \(5.59\times 10^{-6}\) \\  & HD-10-03 & 8.0 & Lifting & 0.5–10.12 & \(7.35\times 10^{-6}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Calculation result statistics of slug tests. Figure 8: Calculation results of slug tests in different section positions. slug test in the same test section as the water pressure test, based on the assumption of the rock mass equivalent permeability coefficient. The test section ranges of the first group of the water pressure test are 1.06 to 4.76 m. Therefore, it is required that the equivalent permeability coefficient determined by the slug test corresponding to this test section ranges compares with the water permeability calculated by the water pressure test. However, the test section ranges of the sixth group of the slug test are 0.5 to 4.76 m, and the test section ranges of the first group of the slug test are 0.5 to 0.89 m. The test section ranges of the first group of the slug test are included in the test section ranges of the sixth group of the slug test. Therefore, the equivalent permeability coefficient from 0.89 to 4.76 m can be calculated based on the slug test data, according to the assumed layered rock mass equivalent permeability coefficient method. The test section ranges can be approximately 1.06 to 4.76 m of the test section ranges of the first group of water pressure tests.