## 3 Results  
Geological conditions have a great influence on the mechanical behavior of the tunnel [31]. Through calculation, the longitudinal displacement results after tunnel excavation under different water content conditions are obtained. The results show the deformation trend of tunnel surrounding rock under different water content conditions is consistent. Figure 4 shows the longitudinal deformation contour of surrounding rock with different conditions of water content. The figures indicate that the longitudinal deformation of surrounding rock mainly manifests as vault settlement and arch bottom uplift.  
Figure 4: Longitudinal deformation contour of tunnel surrounding rock under different conditions of water content. (**a**) 0 water content; (**b**) 5% water content; (**c**) 10% water content; (**d**) 15% water content; (**e**) 20% water content; (**f**) 25% water content.  
Taking vault settlement as the main research object, the longitudinal deformation ur of surrounding rock at a certain distance from the tunnel excavation face under different water content conditions is obtained, as shown in Figure 5. The figure shows that, with the increase in water content, the longitudinal deformation of the surrounding rock becomes larger and larger. Especially under 25% water content, the deformation is obviously larger than other water content. Compared with 20% water content, the maximum deformation in the condition of 25% water content increases by 70.2%. This is consistent with the existing research results [30].  
By normalizing the obtained data, the LDP curves under different water content can be obtained, as shown in Figure 6. The figures show that the curves tend to be gentle as the distance from the excavation surface becomes farther and farther. And the curves rise sharply on the excavation surface (i.e., \(x=0\)), indicating that the spatial effect caused by tunnel excavation has influence range, and the influence on the excavation surface is very intense. In the vicinity of the excavation face (i.e., \(x=0\)), with the increase of water content, the growth trend of the LDP curve is steeper, indicating that the release process of surrounding rock stress and displacement is faster. However, with the increase of \(x\), when \(x>0.3R\), the greater the water content of the surrounding rock, the gentler the growth trend of the corresponding curve. The above rules are consistent with the information given in Figure 5. Near the excavation surface, the weakening affection of water content on the surrounding rock's properties is obvious, and the surrounding rock's deformation is severe. For the LDP curve, \(\upmu_{\text{r}}\) under different water content occupies the leading influence position, reflected in the larger the water content of the surrounding rock, the steeper the LDP curve; with the increase of \(x\), when \(x=5\) m (i.e., \(x=0.3R\)), the influence of spatial effect caused by excavation reduces, the trend of surrounding rock deformation is gentle. For the LDP curve, \(\upmu_{\text{max}}\) under different water content occupies the leading influence position, reflected in the larger the water content of the surrounding rock, the gentler the LDP curve. In addition, compared with the unexcavated part (i.e., \(x<0\)), the excavated part (i.e., \(x>0\)) is more affected.  
In summary, for the Xigeda formation, the water content is an essential factor affecting the LDP, which will have a non-negligible impact on the conve  
Figure 5: Comparison of longitudinal deformation of surrounding rock under different water content conditions.