# Research on Control Technology of Large-Section Water-Bearing Broken Surrounding Rock Roadway
## 5 Numerical Simulation Analysis  
### Numerical Modeling  
According to the test results of the physical and mechanical properties obtained from the formation conditions and on-site sampling detailed in the geological survey report, the relevant parameters of the solid units, including the simulated rock strata and the supporting structure, have been selected. Ultimately, the physical and mechanical parameters utilized in the model are presented in Table 3.  
According to the geological summary and engineering situation described above, and because the target area of the simulated roadway is the water-bearing section, it is assumed that the rock mass of the whole model is water-saturated before the simulated excavation of the roadway. According to the elevation data of the groundwater level in the area provided by the field technicians, the pore water pressure at the roadway section is about 1.2 MPa, and then the hydrostatic pressure value is assigned to the numerical simulation grid unit instead of the pore water pressure. The corresponding numerical model is established by using FLAC3D simulation software (FLAC3D 6.0), as shown in Figure 8a. The model size is 50 m long, 50 m wide, and 20 m deep. It is divided into 222,207 grid units and 155,734 grid nodes.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Lithologic** & **Bulk** & **Shear** & **Cohesion** & **Angle of Internal** & **Volumetric** & **Porosity** \\
**Characters** & **Modulus** & **Modulus** & **(GPa)** & **(MPa)** & **(\({}^{\circ}\))** & **(kg/m\({}^{3}\))** & **(\%)** \\ \hline Dolomite & 10 & 8.6 & 5 & 38 & 2750 & 0.2 \\ \hline Slate & 5.12 & 2.31 & 2.32 & 28 & 2690 & 0.5 \\ \hline Soft rock & 1.5 & 0.4 & 0.52 & 20 & 2750 & 0.1 \\ strata & & & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Mechanical and physical parameters of surrounding rock.  
Figure 7: The displacement of the crushing zone under different water content.  
Before excavating the numerical model roadway, the mechanical and physical parameters of the surrounding rock, as presented in Table 3, are substituted into Equations (3) and (4). The resulting radius of the plastic zone is 6.29 m, and the displacement of the broken zone is 86.78 mm. These findings provide verification and serve as a reference for subsequent numerical simulation analyses.  
According to the previous field investigation and the analysis of surrounding rock characteristics, the deformation characteristics and instability mechanism of surrounding rock mass have been basically understood. On this basis, the roadway support is optimized and analyzed, and the optimized support scheme is put forward. Through numerical simulation, the optimized support effect is analyzed and studied. The optimized support scheme adopts the combined support mode of steel arch, local grouting, and mesh shotcrete. Among them, the steel arch adopts a 12 # mining I-steel arch, one every 1 m; the grouting hole is drilled in the weak interlayer of the two sides of the roadway. The slurry is mainly P.O42.5 cement, the pressure of the grouting hole is 3 MPa, and the grouting depth is 6 m. The strength of net shotcrete is C20, and the thickness of shotcrete is 100 mm. The structural diagram of the optimized support scheme is shown in Figure 8b.