# Research on Control Technology of Large-Section Water-Bearing Broken Surrounding Rock Roadway
## 2 Engineering Summary and Analysis of Surrounding Rock Failure Characteristics
### Theoretical Model Establishment and Analysis of Roadway
Analysis of the Influence of Pore Water Pressure on the Radius and Displacement of the Fracture Zone  
In the water-bearing broken surrounding rock roadway, the factors influencing the surrounding rock are varied. This section mainly analyzes the influence of pore water pressure on the radius and displacement of the fracture zone. Notably, the displacement of the surrounding rock is greatest when \(r=R_{0}\), and this displacement is inversely proportional to the elastic modulus (\(E\)). Consequently, the displacement law of the broken zone studied in the following sections is based on the condition where \(r=R_{0}\). Furthermore, the influence of the elastic modulus (\(E\)) and radius (\(r\)) will not be considered in this analysis. The buried depth of the Y1# belt transportation roadway at the 830 working face is 385 m. The lithology of the stratum consists of slate. The cross-section shape of the roadway is a three-center circular arch measuring 4.6 m by 3.85 m. Calculations indicate that the roadway is similar to a circle with a radius of 2.5 m; therefore, the excavation radius of the roadway is set to \(R_{0}=2.5\) m. Considering that the radius of influence of external water is 10 times the radius of the roadway excavation, so let \(R_{s}=25\) m.  
Through the calculation and analysis of MATLAB's Equations (12) and (14), the relationship between pore water pressure and the range and displacement of surrounding rock fracture zone under different supporting forces is calculated with pore water pressure as the influencing factor. Given that the surrounding rock of the roadway is relatively broken and contains a weak interlayer, the cohesion (C) is set at 0.85 MPa. Parameters not included in this discussion are assigned fixed values, as shown in Table 1.  
Analysis of the Influence of Pore Water Pressure on the Range and Displacement of the Fracture Zone  
In order to find out the degree of influence of pore water pressure on the fracture zone of the surrounding rock under different supporting conditions, pore water pressures of 0 MPa, 0.4 MPa, 0.8 MPa, 1.2 MPa, 1.6 MPa, and 2 MPa were applied. The resulting influence curves depicting the influence of different water pressures and the radius and displacement of the fracture zone in the surrounding rock under different supporting conditions are drawn (Figure 4). It can be observed from the figure that as water pressure increases, both the radius and displacement of the crushing zone gradually expand. The main reason for this phenomenon is that following the excavation and unloading of the surrounding rock, the seepage water within the pores and fissures of the rock mass dissipates significantly to the free surface. At this point, the reduction in water pressure diminishes the degree of cementation between the rock mass structures. Concurrently, the two-way effective stress acting on the surrounding rock mass gradually increases, thereby accelerating the failure process of the rock mass structure. As the rate of water pressure dissipation increases, this effect becomes even more pronounced. Consequently, the surrounding rock mass becomes more susceptible to yield failure, ultimately resulting in the observation that higher water pressure correlates with a larger radius and displacement of the fracture zone following excavation and unloading. For example, when the supporting force \(p_{i}=0.3\) MPa, the radius of the surrounding rock fracture zone with a pore water pressure of 0 MPa is 10.29 m, and the displacement of the fracture zone is 89.32 mm. In contrast, the radius of the surrounding rock fracture zone with a pore water pressure of 2 MPa is 14.25 m, and the \begin{table}
\begin{tabular}{c c c c c c} \hline \(p_{0}\)/MPa & \(p_{0}\)/MPa & \(\eta\) & \(\varphi\)/\({}^{\circ}\) & \(E\)/GPa & \(\mu\) \\ \hline
10.36 & 0.8 & 0.3 & 22 & 12 & 0.5 \\ \hline \end{tabular}
\end{table} 
Table 1: Petrophysical parameters. displacement of the fracture zone is 183.26 mm.