# Research on Control Technology of Large-Section Water-Bearing Broken Surrounding Rock Roadway
## 4 Physical and Mechanical Research and Analysis of Water-Bearing Broken Surrounding Rock  
In order to reveal the influence of groundwater on the strength of the surrounding rock, this section obtains the strength characteristics of rock specimens under different water contents by testing rock specimens with different water contents. Through field investigation, rock sampling was carried out in the surrounding rock section of the Y1# roadway in the Yingping section of the Wengfu phosphate mine (as shown in Figure 5) so as to carry out indoor tests. Figure 4: Pore water pressure and broken zone range and displacement relationship curve. Figure 5: Specim sampling points and rock specimens. After the preparation of the rock sample is completed, it is dried and then the specimen is immersed in water. As shown in Table 2, the soaking schemes of the specimens with different water contents are shown. After the specimen is immersed in water, the uniaxial compression tests with different water contents are carried out, as shown in Figure 6. Figure 6a indicates that the peak strength of the rock specimens is negatively correlated with water content. The fitting curve for peak strength demonstrates a trend of slow decline, linear decline, and then slow decline; that is, as water content increases, the peak strength of the rock specimens approaches a fixed value. Specifically, the peak strength of rock specimens with water contents of 0.11%, 0.22%, 0.29%, and 0.41% is reduced by 5.56%, 30.86%, 46.06%, and 55.3%, respectively, compared to the peak strength of the specimens under dry conditions. Therefore, as water content increases, the compressive strength of the rock specimens decreases. It can be observed from Figure 6b that as the water content increases, the elastic modulus (\(E\)) decreases during the elastic deformation stage of the stress-strain curve. The elastic modulus of the rock specimens exhibits a negative correlation with water content, following a negative exponential function. When the moisture content is 0.11%, the elastic modulus decreases by 20.43% compared to the modulus measured during drying. At a moisture content of 0.22%, the elastic modulus decreases by 38.75% relative to the drying condition. When the moisture content reaches 0.29%, the elastic modulus decreases by 51.18% compared to the drying state. At a moisture content of 0.41%, the elastic modulus decreases by 59.31% compared to the modulus during drying. This indicates that as water content increases, the softening of the rock specimens becomes more pronounced, resulting in a shorter elastic deformation stage. Additionally, it can be concluded that the Poisson's ratio of the rock specimens increases exponentially with rising water content. Compared to the dry state, the Poisson's ratio increases by 7.51%, 19.72%, 30.99%, and 42.25% at moisture contents of 0.11%, 0.22%, 0.29%, and 0.41%, respectively. Figure 6: Strength characteristics of rock specimens under different water content: (**a**) peak strength; (**b**) elastic modulus and Poisson’s ratio. In Figure 6b, the fitting formulas of water content and elastic modulus \(E\) and Poisson's ratio \(\mu\) are obtained, respectively:  
\[E_{(\delta)}=16.61e^{\frac{-\delta}{64.65}}-0.364 \tag{15}\]  
\[\mu_{(\delta)}=0.108^{\frac{-\delta}{64.61}}-0.105 \tag{16}\]  
Equations (15) and (16) are substituted into Equation (14), and the parallel standing Equation (12) can obtain the relationship between different water content and the displacement of the crushing zone:  
\[u_{p}=\frac{\left(0.108e^{\frac{-\delta}{64.65}}-1.105\right)R_{p}^{2}}{\left( 16.61e^{\frac{-\delta}{64.65}}-0.364\right)r}\{[p_{0}+(1-2\eta)p_{w}]\sin\varphi +2C\cdot\cos\varphi\} \tag{17}\]  
In the above equation, except for the moisture content of the independent variable, the remaining variables take the fixed value.