<p>Empirically based seismic - analysis methods that rely on recorded ground motions are routinely used to evaluate structural damage and guide the design of high-speed railway track-bridge systems (HSRTBS). Their accuracy, however, is constrained by the sparse distribution of seismic stations, especially in rugged terrain where ground-motion variability is pronounced. To overcome this limitation, this work utilizes high-precision, physics-based numerical simulations to model complex spatial seismic wave fields. Leveraging the sub-fault input interface provided by SPECFEM3D, we construct a kinematic hybrid source model of the 2016 Meinong <i>M</i>_w 6.4 earthquake and simulate the complete source-path-site process. The resulting wave field is validated against observed records and by comparing RotD50 intensity measures with the NGA-West 2 ground-motion prediction equations. After verification, a detailed dynamic analysis of the HSRTBS is performed under both the synthetic and recorded seismic excitations. The results show excellent agreement, demonstrating that physics-based ground-motion simulations can effectively characterize the spatiotemporal evolution of seismic wave fields in complex terrain. This method addresses the limitations of sparse seismic station records and provides reliable, site-specific, and spatially variable seismic inputs. These findings confirm the feasibility and robustness of physics-based ground-motion simulations as a reliable alternative to conventional empirical approaches for the seismic analysis of the HSRTBS.</p>