## 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
Similarly, the test section ranges of the water pressure test are 4.37 to 10.12 m, so it is necessary to calculate the equivalent permeability coefficient determined by the slug test that corresponds to this test section ranges. However, the test section ranges of the tenth group of the slug test are 0.5 to 10.12 m and the test section ranges of the sixth group of the slug test are 0.5 to 4.76 m. So, the equivalent permeability coefficient from 4.76 to 10.12 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 4.37 to 10.12 m of the test section ranges of the second group of water pressure tests. Similarly, the test section ranges of the third group of the water pressure test are 1.37 to 10.12 m, and the equivalent permeability coefficient determined by the slug test corresponding to this test section ranges shall also be calculated. The test section ranges of the tenth group of the slug test are 0.5 to 10.12 m, and the test section ranges of the second group of the slug test are 0.5 to 1.3 m. Therefore, similarly, according to the assumed layered rock mass equivalent permeability coefficient method, the equivalent permeability coefficient from 1.3 to 10.12 m can be calculated based on the slug test data. The test section ranges can be approximately 1.37 to 10.12 m of the test section ranges of the third group of water pressure tests. The equivalent permeability coefficient of fractures by the slug test in the test section corresponding to the three groups of water pressure tests is calculated, according to the assumed layered rock mass equivalent permeability coefficient method. The calculation results are shown in Table 5.  
According to the relationship between water permeability and permeability coefficient in the Chinese \"Code for engineering geological investigation of water resources and hydropower\" (GB50487-2008) [29], it can be observed from Figure 9 that the water permeability calculation results of the three groups of water pressure tests are basically consistent with the equivalent permeability coefficient results determined by the slug test in the corresponding test section, which can indicate the accuracy and applicability of the proposed slug test method and self-developed test system used to determine the fracture permeability coefficient, which is more convenient and efficient than other test methods. \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Test Section No.**} & **Test Section Ranges of** & **Test Section Ranges of Slug** & **Water Permeability (Lu)** & **Equivalent Permeability** \\  & **Water Pressure Tests (m)** & **Tests (m)** & & **Coefficient (cm/s)** \\ \hline Test section No. 1 & 1.06–4.76 & 0.89–4.76 & 9.9 & 5.12 \(\times\) 10\({}^{-5}\) \\ Test section No. 2 & 4.37–10.12 & 4.76–10.12 & 3.9 & 0.94 \(\times\) 10\({}^{-5}\) \\ Test section No. 3 & 1.37–10.12 & 1.3–10.12 & 2.8 & 2.35 \(\times\) 10\({}^{-5}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Water permeability of three group water pressure tests and fracture equivalent permeability coefficient determined by slug tests of the corresponding test section.