# Model Test on Effect of Ground Fissure on the Behavior of Oblique Two-Section Subway Tunnel
## 3 Results and Discussion  
### Acceleration Response of Soil  
#### 3.1.1 Dynamic Response at Different Depth  
The results from test points of A3, A7, and A10 in the hanging wall, and A2, A6, and A9 in the football were analyzed to investigate the dynamic response at different embedded  
Figure 6: Layout of pressure cells in the soil (unit: cm): (**a**) elevation view of pressure cells layout; (**b**) top view of pressure cells layout at the height of 15 cm; (**c**) top view of pressure cells layout at the height of 50 cm; (**d**) top view of pressure cells layout at the height of 85 cm. Figure 7: Layout of pressure cells and strain gauges on the subway tunnel (unit: cm). depth. Figures 8 and 9 show the acceleration time series and the peak acceleration curve at test points under 10 Hz excitation at 60 and 100 cm from the right margin of the tunnel. When the vibration exciter at 60 cm works, the peak acceleration at points A6 and A7 (0.06 and 0.13 m/s\({}^{2}\), respectively) is obviously higher than that at A2 and A3 (0.04 and 0.11 m/s\({}^{2}\), respectively), indicating the attenuation effect of the soil layer on the subway-induced vibration. Meanwhile, peak acceleration at points A9 and A10 at the tunnel crown is quite low in such a condition, with values of 0.02 and 0.08 m/s\({}^{2}\), respectively. When the vibration exciter at 100 cm works, the test results show a similar variation as the test points at the tunnel bottom, which show the largest peak acceleration, and the points at the tunnel crown and 10 cm below the tunnel bottom, which show the decreasing peak acceleration. In general, the soil acceleration attenuates both upward and downward from  
Figures 10 and 11 show the acceleration time series and peak acceleration of test points (A2, A3, A6, A7, A9, A10) under the combined impact of the ground fissure descending (1 cm) and 10 Hz excitation at 60 and 100 cm from the right margin of the tunnel. Results show a complicated stress state for soil and tunnel near the ground fissure because of the oblique intersection between the ground fissure and tunnel. Figure 10: _Cont_. Figure 9: Peak acceleration curves under the scenario of inactive ground fissure: (**a**) vibration exciter at 60 cm; (**b**) vibration exciter at 100 cm. In the central axis section of the tunnel, voiding and compacting phenomena between the tunnel and soil mass are identified near the ground fissure. Among them, the tunnel bottom in the hanging wall and the tunnel crown in the football are voided from the soil, while the tunnel crown in the hanging wall and the tunnel bottom in the football are compacted with the soil. Moreover, the variation of the contact state between the tunnel and soil also affects the propagation process of vibration. When the vibration exciter at 60 cm from the right margin of the tunnel works, the test points of A6 and A2 that are below the tunnel in the hanging wall present a decreasing acceleration (0.04 and 0.02 m/s\({}^{2}\), respectively) due to the impact of the partial void, while the compaction causes the increase in acceleration at point A9 (0.03 m/s\({}^{2}\)). Similarly, A7 and A3 test points at the tunnel bottom in the football show a decreasing peak acceleration (0.14 and 0.12 m/s\({}^{2}\), respectively), while the A10 point shows an increasing one (0.07 m/s\({}^{2}\)). Additionally, the test results of the scenario that the vibration exciter at 100 cm works also show a similar variation, except for a higher peak acceleration in the compaction region and a lower acceleration in the voiding region. Figure 11: Peak acceleration curves under the scenario of hanging wall descend 1 cm: (**a**) vibration exciter at 60 cm; (**b**) vibration exciter at 100 cm. Figure 10: Acceleration time series under the scenario of hanging wall descend 1 cm: (**a**) vibration exciter at 60 cm; (**b**) vibration exciter at 100 cm. In summary, for a two-section subway tunnel, the peak acceleration of soil shows the maximum value near the tunnel bottom and decreases with the increase in distance from the vibration exciter.