## 4 Conclusions  
In this work, a combination of a model test and numerical simulations is used to reveal the dynamic response characteristics of a pile-soil composite foundation with an adjacent tunnel, using peak vibration acceleration, peak vibration velocity, and peak vibration displacement as evaluation indexes. The conclusions can be summarized as follows:  
1. For the model test and FE simulation, the peak acceleration is at maximum at the ground surface when the train load is applied. The peak acceleration inside the foundation decreases with the increase in the distance from the ground surface and the pile and decreases significantly at the buried depth of the tunnel. The dynamic response of the tunnel lining near the vibration source is significantly greater than that of the other side, and the adjacent tunnel has an obvious vibration isolation effect. Figure 14: Reduction in dynamic response indexes from tunnel roof to tunnel floor. (**a**) Peak vibration acceleration. (**b**) Peak vibration velocity. (**c**) Peak vibration displacement. 2. When the moving train load is applied, the distribution characteristics of peak vibration acceleration, peak vibration velocity, and peak vibration displacement are similar. The dynamic response indexes of the ordinary pile-ground foundation vary less. Due to the superposition effect of the pile group, the dynamic response indexes show a \"wavy\" distribution with the increase in the horizontal distance from the pile. When there is an adjacent tunnel, the dynamic response indexes increase significantly, and the largest increases are 142%, 58%, and 41% at the buried depth of the tunnel roof, respectively. The dynamic response indexes between the adjacent tunnel and the pile are characterized by a monotonic distribution and decrease with increasing distance from the pile. 3. According to the security control thresholds of the peak vibration velocity of the underground structure, the foundation within 3.6 m from near pile is in the dangerously affected zone at the burial depth of tunnel, the foundation 3.6-11.4 m away from the pile is in the strongly affected zone, and the foundation outside 11.4 m from pile is in the weakly affected zone. Similar engineering cases can refer to this method to evaluate the impact due to moving train loads and determine whether vibration damping measures are required. 4. When there is an adjacent tunnel, the dynamic response of the pile-soil foundation is positively correlated with the increase in the train speed under the moving train loads and the dynamic response indexes increase the most at the surface. With the increase in train speed, the impact of the tunnel structure on the attenuation of the dynamic response induced by moving train loads within the pile-soil foundation becomes more evident, especially the peak vibration acceleration. The conclusions drawn from the study of the dynamic response of the pile-soil foundation with the adjacent tunnel under high-speed train load have certain engineering application value for similar projects. However, there are still some problems to be further studied: the influence of different geological conditions and structural materials on the dynamic response needs to be further studied. The vibration isolation measures that may be adopted in practical engineering have a certain impact on the final results. Q.X. : methodology, writing-original draft. Y.Z. : conceptualization, funding acquisition, writing-review and editing. S.X. : investigation, software. H.F.: funding acquisition, project administration. D.W.: investigation. C.W. : data curation. M.Z. : data curation. D.X. : visualization. Y.L. : funding acquisition, resources. All authors have read and agreed to the published version of the manuscript.