## 3 Experimental Results and Analysis  
### Excess Pore Water Pressure  
To clearly describe the variations of excess pore water pressure during the vibration excitation, the excess pore water pressure ratio, \(R_{\text{u}}\), was defined as follows:  
\[R_{\text{u}}=\Delta u\ /\ \sigma \tag{1}\]  
where \(\Delta u\) and \(\sigma\) were the measured excess pore water pressure and the total stress, respectively. In previous studies, the excess pore water pressure ratio has often been defined as the ratio of excess pore water pressure to effective stress, with 1.0 used as the liquefaction standard [37]. The total stress was generally larger than the effective stress in the liquefaction process. Therefore, in this test, the criterion for liquefaction to occur was that \(R_{\text{u}}\) reached 0.8. The layout diagram of the pore pressure gauge is shown in Figure 4. Due to the limitations in article length, for this paper, only the excess pore water pressure of P1, P3, P4, P5, and P7 measurement points were analyzed when PGA = 0.10 g and PGA = 0.20 g. Furthermore, the seismic response was more significant when PGA = 0.10 g and PGA = 0.20 g. Figure 6 shows the time-history curve of excess pore water pressure ratio. In the figure, 2.5 s was taken as the start time of the vibration excitation input. Under the action of PGA = 0.10 g, the excess pore water pressure ratio of the test group was significantly lower than that of the conventional group. This is due to the fact that the excess pore water in the conventional group could only be discharged from the soil through the irregular drainage channels formed by the soil during vibration excitation. The drainage channels formed between the drainage structure and pebbles in the test group had better drainage effects than those in the conventional group, thus effectively reducing the development of excess pore water pressure. In addition, the peak excess pore water pressure ratio of the conventional group reached 0.8 at the P7 measurement point, indicating that the soil in the conventional group had been liquefied. However, the peak excess pore water pressure ratio of the test group also occurred at the P7 measurement point, but its value was only 0.6, meaning it did not reach the liquefaction standard. When PGA = 0.20 g, after inputting vibration excitation, the excess pore water pressure ratio of both sites underwent rapid increase of about 1.5 s to reach the peak value. After reaching the peak, the excess pore water pressure ratio of the conventional group was maintained at a higher level compared to that of the test group, but the difference between them was not as large as when PGA = 0.10 g. This indicates that the effect of the drainage structure in the test group decreased as the vibration intensity increased. When the vibration excitation stopped, the excess pore water pressure ratios of the test and conventional groups started to decrease. Figure 7 shows the vertical and horizontal variation of the peak excess pore water pressure ratio in the two sites. Under the action of PGA = 0.10 g, the peak excess pore water pressure ratios at the three measurement points were less in the test group than in the conventional group, being 0.69, 0.66, and 0.62 times greater than in the conventional group along the depth. Meanwhile, the peak excess pore water pressure ratio decreased with the increased of buried depth, which indicates that when the vibration excitation is input, the upper layer of the site liquefies first, and then gradually the lower layer. This