###### Abstract  
A series of dynamic large-scale model tests and three-dimensional finite element analyses were conducted to investigate the dynamic response of track embankment and XCC pile-raft composite foundation in soft soil for a ballastless high-speed railway under moving train loads. The results indicate that the vibration velocity obtained from the FE numerical simulation agrees well with that from the model test in vibration waveform, amplitude, and frequency characteristics. The peak values corresponding to the passing frequency of train carriage geometry (lc = 25 m), bogie (lab = 7.5 m), and axle distance (lwb = 2.5 m) respectively reflect the characteristic frequencies of the train compartment, adjacent bogie, and wheel load passing through. The peak velocity significantly depends on the distance from the track center in the horizontal direction, of which the attenuation follows the exponential curve distribution. The vibration velocities decrease rapidly within embankment, show a vibration enhancement region from raft to the 1 m depth of foundation soil, then decreases gradually along the subsoil foundation, to a very low level at the bottom of the subsoil, which is much lower than that at the track slab and roadbed. The pile-raft composite foundation can reduce the vibration level effectively and improve the safety of trains running in soft soil areas. high-speed train loads; XCC (X-section cast-in-place concrete) pile-raft foundation; large-scale model test; soft soil; vibration propagation; attenuation +
Footnote †: journal: Applied Sciences  
**Citation:** [PERSON]; [PERSON]. Experimental and Numerical Study of the Dynamic Response of XCC  
Pile-Raft Foundation under  
High-Speed Train Loads. _Appl. Sci._**2021**, _11_, 9260. [[https://doi.org/10.3390/app11199260](https://doi.org/10.3390/app11199260)]([https://doi.org/10.3390/app11199260](https://doi.org/10.3390/app11199260))  
Academic Editor: [PERSON]  
Received: 12 September 2021  
Accepted: 3 October 2021  
Published: 6 October 2021  
**Published:**  
**Subfileware's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. in soils underneath the track structure by faster trains will inevitably cause larger permanent settlements. [PERSON] and [PERSON] [8] proposed a substructure approach to study the dynamic interaction of track structures and layered soils under moving train loads. They indicated that the excessive response at high speeds should be controlled by applying the soil improvement technique at the track as demonstrated from the computer simulation by [PERSON] [2], [PERSON] and [PERSON] [4], and actually taken at the site as reported by [PERSON] and [PERSON] [3]. [PERSON] et al. [11] developed an analytical model to assess the design parameters of a slab track railway system from a dynamic viewpoint. They indicated that for high frequencies, an increase of the track stiffness is most effective, whereas for low frequencies, soil improvement is a better solution. Soft ground improvement using piles has increasingly been used as a rapid construction technique for high-speed railway embankments over soft soil areas. The bear capacity of piles and pile-soil interaction effect under different loading conditions have been studied by [PERSON] and [PERSON] [12] and [PERSON]; [PERSON] et al. [13]. Extensive studies have been carried out to obtain insight into the mechanisms of the geosynthetic reinforced pile supported (GRPS) embankment by considering the pile-soil interactions [14; 15; 16; 17; 18]. [PERSON] et al. [16] studied the properties of soil arching under a dynamic load by using numerical methods and model tests. [PERSON] et al. [19] developed a three-dimensional finite element method (FEM) to study the dynamic responses of GRPF under high-speed rail loads. [PERSON] et al. [20] established a two-dimensional plane model to investigate the influence factor on soil arching for a pile-supported railway embankment subjected to train-induced loadings.