## 3 Analysis of the Results
### Sensitive Study under the Different Geological Conditions  
To study the effect of the two support schemes under different geological conditions, sensitive studies were carried out, and the results were expressed by some typical dates that have been analyzed in Sections 3.1 and 3.2. In the two-dimensional tunnel cross section analysis, the support spacing was set to 3 m, as in Section 3.1. The maximum stress, the displacement, and the failure zone area were given. In the axial analysis, the support effect ratio of the non-radial to the radial support of the support face were given. Thus, the variation of the support effect under different geological conditions could be evaluated accurately. The results are shown in Figures 18-21. Figure 17: Support influence domain diagram and three typical situations: (**a**) influence domain diagram (**b**) support spacing = domain length, (**c**) support spacing = 50% of the domain length, and (**d**) spacing = 25% of domain length (the colors represent the magnitude of the effect of the influence domain). Figure 19: Displacement and variations of the support face under the two support schemes: (**a**) unsupported displacement, (**b**) roof displacement variations, and (**c**) lateral displacement variations. Figure 20: Failure zone area and variations of the support face under the two support schemes: (**a**) unsupported failure zone area and (**b**) failure zone are variations. Figure 18 presents the maximum stresses and their variations under the three geological conditions. Figure 18a shows the maximum vertical and horizontal stress without the support around the tunnel. Apparently, the vertical stress remained almost constant (about 82 MPa) under different geological conditions. The maximum horizontal stress was constant (about 61 MPa) with a good rock mass quality, but it increased greatly (about 10 MPa) under the soft geological condition. Figure 18b,c shows the stress growth rate caused by the support. When the rock mass became softer, the vertical stress grew greatly, and the horizontal stress also increased, but only by a small amount, which demonstrates that the support effect on the vertical stress was more obvious than that of the horizontal stress with the change in the geological conditions. Finally, the difference between the radial and non-radial support was very small. Figure 19 shows the displacement reductions and their variations under the three geological conditions. As expected, as shown in Figure 19a, the displacement was reduced with the rock mass of a better quality, and the displacement difference between the roof and the lateral was small. Figure 19b,c shows the roof and lateral displacement reduction rate. Apparently, the reduction rate of the radial support was always higher than that of the non-radial support, which demonstrates that the support effect of the radial was always better than that of the non-radial support. Moreover, the difference in the curve was close to a constant, which reveals that the support effect ratio remained almost constant under different geological conditions. Figure 20 describes the failure zone area variation. Figure 20a shows that under the unsupported condition, the failure zone area was reduced with the better rock mass quality, as one would intuitively expect. In Figure 20b, the failure zone area reduction rate was the highest for the medium geological condition and the lowest rate was found at the Stiff geological condition and well below the other. The reason for this could be that in the Stiff geological condition, the tunnel had better stability, so that the support did not have much of an effect. In contrast, the effect of the support on the soft geological condition was not enough to stabilize the tunnel, which resulted in a lower reduction rate. Figure 21 shows the support effect ratio of the non-radial to the radial support. The higher ratio shows that the support effect of the non-radial was closer to the radial. Apparently, this rate was higher for the softer rock mass.