## 4 Discussion
### Effect of Ground-Borne Vibrations on the Building  
Vibrations generated as a result of human activity, as it is known, can propagate in the ground, and even over long distances--mainly in the form of Rayleigh waves. Depending on their intensity and the frequency of vibration, they may be imperceptible by the building, or cause more or less significant damage to it. At the junction of the ground and a building, a so-called dynamic soil-structure interaction takes place, and as a result, there is normally a significant reduction of vibrations that are transmitted to the structure. Theoretically, only very rigid buildings that are bound to the rigid ground (rocks) will be subjected to the same forces as the ground. There is virtually never infinite rigidity of the ground, and consequently, at the interface between the ground and the building structure, there will always be a certain radiation and dissipation of energy. The degree of vibration reduction depends on the dynamic parameters of the building and the ground. The main role in dynamic interaction is played by the natural frequency of the building and the shear stiffness of the ground. Besides, there are also very important factors, such as the geometry of the foundation, the method of foundation embedment, the impact of building load on the soil stiffness, soil stratification, shear stiffness with depth, shear strains on soil stiffness on the rigidity of the ground, the frequency of vibrations propagated in the ground, etc. [22]. In accordance with theoretical considerations, guidelines of ISO 4866:2010 [22], DIN 4150-1 [23], and other works, e.g., [24], it is assumed that for most of the vibrations are related to human activity, the ratio of vibration amplitudes recorded on the foundation of the building (\(u_{F}\)) and amplitudes recorded on the surface of the ground in the immediate vicinity of the building (\(u_{N}\)), should be unity or less (\(r_{N}=u_{F}/u_{N}\approx 1\) or \(r_{N}<1\)) [22]. As it can be seen from data shown in Table 2; Table 4, a lower level of vibrations recorded in the building was not always the case--as exemplified by the vibrations recorded on the building at the first measurement point (MP1--located on the outer foundation wall of the building at the level of the adjacent terrain from the side of the source of vibrations) during the operation of the hydraulic compactor in the first stage of the research (source of vibrations at a distance of 15 m from the building)--in X2 mode and 0.4 m (see Table 2, direction x), in X3 mode at a depth of 2.0 (see Table 2, direction y), and vibrations generated by the work of the plate compactor at a depth of 0.4 m (see Table 2, direction x) and 1.2 m (see Table 3, stage II, direction x). In each of these cases, a resonant vibration of the building could have occurred. Each building structure based on the ground is subject not only to loads resulting from the weight of the structure, service loads, and external loads associated with wind pressure and suction, snow load or other atmospheric influences--including loads resulting from variable temperatures and ambient humidity. There are also loads that are related to the uneven settlement of the ground under the foundations, thermal stresses in elements exposed to direct sun impact, or additional stresses in individual structural elements associated with executive or design errors. Long-lasting vibrations propagated in the ground may also contribute to accelerated consolidation or compaction of the soil in the immediate vicinity of buildings and directly under them--as a result of which, damage to structural elements (e.g., cracking of foundations and walls) may occur in buildings exposed to this type of dynamic impact as the effect of exceeding the permissible stresses, even if the level of vibrations propagated in the soil was relatively small, and as such, they could not cause this type of damage.