## 3 Experimental Validation of the Models
2, vibration frequencies were transmitted without changes up to about 7.8 Hz. Above a frequency of about 8 Hz in the frequency characteristic of foundation vibrations, the influence of the building in attenuating the dominant frequencies occurring in the ground was visible--comp. Figure 9b. Figure 8: Measured free-field and foundation vibration of the actual building and the corresponding Fourier spectra in the case of horizontal transverse direction (x): (**a**) induced by the mining tremor No. 1; (**b**) induced by the mining tremor No. 2. To verify and assess the suitability of the proposed models, a comparison of the measurement results of the horizontal components of vibration at the foundation level with those calculated for the three analyzed variants of the subsoil model was carried out in terms of the vibration waveforms in the time domain, the dominant frequencies, and the maximum values of acceleration vibrations. These comparisons are shown in Figures 10 and 11 and in Table 2.  
In the case of mining tremor No. 1, for the horizontal component x of vibrations, larger maximum values of vibrations at the foundation level were obtained for the SM1 model than from measurements. This proves that the SM1 model does not correspond well with the real building. A similar result was obtained for mining tremor No. 2. Good agreement between the calculated records of the x component of vibrations was obtained for the SM2 and SM3 models, with slightly larger values calculated for the SM2 model, which results from taking into account the damping in the SM3 model. Figure 9: Measured free-field and foundation vibration of the actual building and the corresponding Fourier spectra in the case of horizontal longitudinal direction (y): (**a**) induced by the mining tremor No. 1; (**b**) induced by the mining tremor No. 2. In the calculated FFT course for the horizontal component x for mining tremor No. 1, low components were visible in the range of 4.4-5.2 Hz and from 9.3 to 10.4 Hz. Higher vibration components were 12 to 17.5 Hz. In the FFT course for the waveform of the x component of vibrations from measurements, vibration components at frequencies of 6-8.5 Hz were also visible, which did not appear for the SM2 and SM3 models. In the calculated FFT course for the horizontal component x for mining tremor No. 2, low components were smaller than for mining tremor No. 1 and remained in the range of 3.5-5.2 Hz and from 8.7 to 9.7 Hz. The dominant low frequencies in the vibration waveforms calculated at the level of the foundations for the analyzed models corresponded well with those obtained from in situ vibration measurements. Additionally, in the SM1 model, higher dominant frequencies from the range of 13.5 to 15 Hz were visible. In the case of the y-component of vibrations for mining tremors No. 1 and No. 2, significantly higher maximum vibration values at the foundation level were obtained in the  
Figure 10: Foundation vibration of the masonry building (brick load-bearing walls) and the corresponding Fourier spectra computed using SM1, SM2, and SM3 subsoil models vs. measured building foundation vibration in the case of horizontal transverse direction (x): (**a**) induced by the mining tremor No. 1; (**b**) induced by the mining tremor No. 2.  
case of a fully fixed model (SM1, nonflexible subsoil) compared with measured vibrations. This is due to the greater stiffness of the fixed model compared with the actual building. The calculated maximum values of the horizontal component y of vibrations for the SM2 and SM3 models did not show significant differences. This proves the negligible effect of damping included in the SM3 model. A representative record of the horizontal component y of vibrations (mining tremor No. 1) measured at the foundation level was characterized by a wide band of dominant low frequencies from 6.3 to 9 Hz. However, a dominant low frequency of about 6.3 Hz could be distinguished.