## 3 Experimental Results and Analysis
### Acceleration  
This section compares and analyzes the time-history curves of the acceleration of the test group and the conventional group when PGA = 0.20 g. The time-history curves of the acceleration when PGA = 0.20 g are depicted in Figure 8; in the figure, 1.0 s was used as the start time of the vibration excitation input. To facilitate the analysis of the test results, the time-history curves were divided into three stages: Stage 1 (within 1.5 s after the vibration excitation input); Stage 2 (between 1.5 s and 2.0 s after the vibration excitation input); and Stage 3 (between 2.0 s and 10.0 s after the vibration excitation was input). In Stage 1, the acceleration of the conventional group increased rapidly and attained peak acceleration. At this time, the foundation was not yet liquefied and had a certain shear strength. In Stage 2, the acceleration of the conventional group rapidly decreased to about half the peak acceleration, indicating that the site liquefied and the soil lost most of its shear strength. In Stage 3, the acceleration of the conventional group remained almost constant. On the whole, in Stage 3, the peak acceleration of the test group was larger than that of the conventional group, indicating that the drainage structure could effectively maintain the shear strength of the foundation soil and had a reinforcement effect on the bridge pile foundation. It should be noted that the acceleration of the A7 measurement point in the conventional group gradually decreased in Stage 3 because the A7 measurement point was close to the ground surface and the liquefaction was intense. In addition, the time-history curves of the acceleration recorded at the A3 and A8 measurement points of the conventional group were asymmetric, which may have been caused by the tilting of the accelerometer during the vibration excitation.  
Figure 9 shows the acceleration amplification factors (i.e., the ratio of peak acceleration at the measurement point to peak acceleration input from the shaking table) of measurement points A1, A2, A3, A4, and A6. Under the action of PGA = 0.10 g, the acceleration amplification factors of both sites were larger than 1, and gradually decreased with the increase of buried depth, indicating that the upper layer of the foundation would be liquefied first, which conforms to the general laws of foundation liquefaction during earthquakes. The acceleration amplification factors of the measurement points in the test group were 1.06, 1.04, and 1.03 times those of the conventional group from top to bottom,  
Figure 7: Distribution of the peak excess pore water pressure ratio along the vertical and horizontal directions.  
and 1.05, 1.04, and 1.02 times those of the conventional group from far away from the sheet-pile wall to near the sheet-pile wall. When PGA = 0.20 g, the acceleration amplification factors of the two sites were greater than those measured under the action of PGA = 0.10 g, and the acceleration amplification factor of the test group was still larger than that of the conventional group, indicating that the drainage structure could discharge the excess pore water in the soil in a timely manner, thus maintaining a higher shear strength in the foundation.  
Figure 8: Time-history curves of the acceleration (when PGA = 0.20 g).  
Figure 9: Distribution of the acceleration amplification factor along the vertical and horizontal directions.