## 3 Results and Discussion
### Analysis of Rock Formations in the Area of Influence
#### 3.1.1 Total Displacement Response
Right side wall measurement points: The slope of the MS1 and MS2 profile measurement points in the S2-S4 excavation and support after the displacement growth shows a growing trend and the displacement difference between the measurement points gradually increases from the tunnel structure measurement point to the point away from the tunnel body measurement, while the displacement value gradually decreases; after that (S5-S10), the displacement growth slope gradually decreases, and the displacement value of the measurement points does not differ after the tunnel. After the excavation and support of S2-S4, the slope of displacement growth shows an increasing trend and the displacement difference between the measuring points gradually increases; after the excavation and support of S5-S8, the slope of displacement growth remains stable and the displacement difference between the measuring points does not change much, while the displacement value gradually decreases from the measuring point of the tunnel structure to the point far away from the tunnel body; after that, the slope of displacement growth decreases and there is not much difference in the displacement value of the measuring points after the tunnel passes through; after the excavation and support of S4, the displacement growth slope decreases and there is not much difference in the displacement value of the measuring points after the tunnel passes through. After the excavation and support of S8, the slope of displacement growth tends to increase, the displacement difference between the measuring points gradually increases, and the displacement value from the tunnel structure measuring point to the measuring point far away from the cave body gradually decreases; after that (S9 and S10), the slope of displacement growth gradually decreases and there is not much difference in the displacement value of each measuring point after the tunnel. The displacement difference between the measurement points gradually decreases and the displacement value gradually increases from the tunnel structure measurement point to the measurement point far away from the tunnel body; the displacement growth tends to increase, the displacement difference between the measuring points gradually increases, and the displacement value from the tunnel structure measuring point to the measuring point far away from the cave body gradually decreases; after that (S9 and S10), the slope of displacement growth gradually decreases and there is not much difference in the displacement value of each measuring point after the tunnel. The displacement difference between the measurement points gradually decreases and the displacement value gradually increases from the tunnel structure measurement point to the measurement point far away from the tunnel body; the displacement growth slope decreases after the excavation of S10 and there is not much difference between the displacement values of the measurement points. In summary, the displacement of the base plate of the existing tunnel is greatly affected by the excavation time step, and the change rule of the top plate and the left and right side walls is similar. The trend of displacement change at the measuring point is mainly determined by the distance between the excavation surface and the typical profile, and the 40 m range in the middle of the tunnel measuring point is the sensitive area affected by the excavation, which shows slow growth when the distance is far away and fast growth when the distance is close.