###### Abstract  
The soil engineering geological characteristics and hidden fault creep activity are the main geological factors affecting the stability of the Beijing-Zhangjiakou high-speed railway foundation. In order to reveal the deep formation structure and physical and mechanical properties of the soil under the Beijing-Zhangjiakou high-speed railway foundation and explore the influence of soil settlement under the static load and dynamic load of high-speed railways, according to the deep-hole engineering geological drilling and soil test, this paper reveals the soil structure and physical and mechanical properties within a 500 m buried depth of the Huailai section of the Beijing-Zhangjiakou high-speed railway. Based on the drilling data, we constructed a 3D geological structure model across fault segments to study the influence mechanism of the dynamic load of trains on differential ground settlement. The results show that the basic physical and mechanical parameters of all kinds of soil have little change with the increase of buried depth, and the ratio of secondary consolidation index \(\rm C_{s}\) to compression index \(\rm C_{c}\) is 0.0036-0.0516. Under the dynamic load of a high-speed train, the vertical displacement of soil gradually decreases with the increase of depth, which mainly affects the soil within a 50 m depth. Within the influence range, the vertical displacement at a certain point is negatively correlated with the speed of a high-speed railway and the horizontal distance from the railway line and the fault. The research results are expected to provide scientific support for the safe operation of the Beijing-Zhangjiakou high-speed railway. deep engineering geology drilling soil test; dynamic load of train; differential settlement 2023200202313266202313200231320023132002313200231320023132002313200231320023132002313200231320023132002313200231320023132002313200231320023132023132002313200231320231320  
speed railways, such as the Beijing-Tianjin high-speed railway (Beijing section), the Beijing-Shanghai high-speed railway (Tianjin, Suzhou-Wuxi-Changzhou section) and the Lu Nan high-speed railway (Heze, Jining section) [1; 2; 3; 4]. The research shows that the load is the main external cause of the settlement of railway subgrade, and the difference of subgrade geotechnical engineering characteristics is the main internal cause. The predecessors have studied the differential settlement of the subgrade, considering the train load as a static load, and achieved fruitful results [5; 6; 7; 8; 9; 10]. In the early stage, [PERSON] et al. (1955) started the research on the strength and deformation of soil under a dynamic load by studying the relationship between the number of cycles and the total deformation of soil [11]. [PERSON] et al. (1975) proposed the exponential cumulative plastic strain formula on the basis of the experimental study to predict the subgrade settlement under the dynamic load of trains [12]. [PERSON] et al. (2010) studied the influence of consolidation conditions and dynamic stress ratio on soil stiffness attenuation characteristics by using dynamic triaxial tests, and established a soil stiffness attenuation model reflecting static and dynamic eccentricity stresses [13]. Under the action of the cyclic dynamic load of a train, the settlement of different engineering geological conditions is different, which leads to the differential settlement of the high-speed railway foundation and threatens the operational safety of the high-speed railway [1]. Under the condition of high-speed running, the effect of the train's dynamic load on a railway track is intensified, and affects the cumulative deformation and dynamic stability of the subgrade [14; 15; 16]. With the rapid development of computer technology and calculation methods, the numerical calculation method has been widely used in dynamic response analysis of the subgrade [17; 18; 19].