Due to the high speed of railway and the railway network passing through an urban area, the construction of tunnel using tunnel boring machine (TBM) has been increasing. During TBM tunneling, a deep filling section, about 3 m in depth, under the slab track is formed by the circular machine head. The research and the design standards for filling this section are currently insufficient. In addition, when the section is filled with lean concrete, it may negatively affect the propagation of train vibration. Therefore, it is necessary to analyze the dynamic behavior of filling materials and follow a suitable filling method. In this study, laboratory tests were conducted to determine the dynamic properties of bottom filling materials. Granular crushed stone with a cement content of 7-13% was selected as the filling material. Numerical analyses that reflect the results of the laboratory tests were also performed to analyze the dynamic behavior of the filling section under slab track. The results of these analyses showed that resonance occurred in the filling section depending on the critical and subcritical speeds of the vehicle. Keywords: TBM Tunnel, Bottom Filling Materials, Vibration of Slab Track, Resonance