With the gradual densification of China’s railway network, more and more railways are inevitably crossing active fault zones. Creep dislocation and stick–slip dislocation of the fault zones can lead to uneven deformation and cracks in the railway subgrade, threatening the sustainability of the railway. Therefore, a model test and numerical simulation were used to analyze the deformation mechanism and sustainability of the subgrade and foundation induced by a strike–slip fault dislocation in a flat site under different angles between the subgrade and fault strikes. The test and simulation results show that (1) under the influence of strike–slip fault dislocation, the horizontal direction of the subgrade appeared to have an S–shaped displacement. The top surface of the subgrade appeared to have a vertical settlement. Further, tension–shear cracks and compression crush zones appeared on the subgrade’s surface. (2) When the angle between the fault and subgrade strikes increased, the subgrade’s uneven deformations induced by fault dislocation first decreased and then increased. The angle between the main tension–shear crack on the top surface of the subgrade and the fault strike showed a trend of increasing and then decreasing. In addition, the compressive stress along the subgrade strike decreased, while the tensile stress along the subgrade strike gradually increased. (3) The tension–shear cracks in the subgrade and foundation were spiral and converged to the basement strike–slip fault along the depth direction. This study provides a reference for the safe operation and sustainability of railways near faults.

The spatial distribution characteristics and slip rate in the Xianshuihe Fault Zone (XSHFZ) are still subject to controversy, and the segments where creeping movement occurs within the fault remain unclear. In this paper, the three-dimensional deformation field of the XSHFZ and its neighboring areas is obtained by integrating InSAR and GNSS data. Subsequently, based on the three-dimensional deformation field, an elastic dislocation model is employed to analyze the slip rate, locking state, and creeping movement within the XSHFZ. The results show that the XSHFZ is a typical sinistral strike–slip fault with compressional characteristics. The slip rate of the XSHFZ ranges from 9.3 to 14.3 mm/yr. The average strike–slip rate of the Qianning and Kangding segments surpasses that of the eastern and western segments, while the Moxi segment exhibits the lowest slip rate. The locking depth of the XSHFZ is estimated to be between 13 and 26 km, with shallow creep movement predominantly concentrated in three segments: Daofu, Qianning, and Kangding, where the shallow creep rate ranges from 1.5 to 4.9 mm/yr. The XSHFZ is known for its short recurrence period of strong earthquakes and frequent seismic activities. A quantitative study of fault slip rates, locking depth, and creeping movement provides essential support for analyzing its seismic hazards. The seismic hazard of each segment of the Xianshuihe Fault Zone (XSHFZ) was analyzed based on the principle of seismic moment balance. The areas with high seismic hazards in the Xianshuihe Fault Zone correspond to the locations of seismic gaps along the fault. Specifically, the Qianning segment and the Yalahe and Selaha faults within the Kangding segment are associated with seismic gaps and are at risk of experiencing earthquakes with magnitudes of 6.9, 6.9, and 6.6, respectively. The results highlight the importance of continuous monitoring and preparedness measures to mitigate the seismic risks present in the XSHFZ.