The state of a rigid disk at elastic waves diffraction on it and the possibility of its oscillation suppression using a multi-mass damper was studied in the paper. The operation of a three-mass dynamic oscillation suppression was considered and its application was compared with the operation of a two-mass damper. The effectiveness of the use of multi-mass dampers was estimated by the relative amplitude of disk oscillations and by the width of the frequency zone. It was stated that to suppress disk oscillations in a state of low instability of external impact frequency, the use of single- or two-mass dampers was sufficient. To reduce the disk displacements at unstable frequency of external impact (to cover a wider frequency zone), it is necessary to use a three-mass damper; the width of the damper effective operation significantly increases (about 4-5 times) compared to the operation of a two-mass damper.

The question of the depth of laying occupies a special place in the seismic protection of underground structures. With a seismic shock, different waves appear in the ground. Upon impact on the surface of the half-space, surface waves arise that have a destructive force for underground structures. Waves with longitudinal and transverse components of displacement, called Rayleigh waves, can occur on the surface. Rayleigh waves have a maximum effect on the surface and quickly fade with depth. To protect against the action of such waves, underground structures are laid deep on the ground. Reducing the depth of laying allows you to reduce costs and facilitates the maintenance of the structure. It will be possible to reduce the influence of Rayleigh waves at a shallower depth using dynamic dampers installed on the structure. The analysis of the work of a dynamic damper to reduce the displacement of an underground cylindrical structure allows us to conclude that the damping effect can be achieved both in terms of displacement amplitude and in the frequency zone width.

The longitudinal vibration of a cylindrical rod has been studied in an elastic medium from the action of axial harmonic forces in a state of compression tension. The consideration took into account the damping of vibration of the rod according to the theory of E.S. Sorokin. Taking into account, internal friction made it possible to approach the real state of the rod as a source of wave radiation. The amplitude-frequency characteristic of the structure is built, taking into account changes in the parameters of the environment and the rod. The possibilities of the emergence of the resonance state of the rod are established. At the same time, cases were considered with and without inelastic properties of the rod material. The analysis of the influence of the properties of the environment and the rod on the amplitude of the displacement of the latter is carried out.

The transverse vibrations of an extended cylindrical underground structure under the action of concentrated forces changing according to a harmonic law are considered. The problem of transverse vibrations of a cylindrical rod interacting with an elastic homogeneous medium was solved by the Fourier method. Approximate solutions are obtained using the method of compensating loads. The influence of soil conditions and geometrical dimensions of the structure, the location of active forces on the amplitude-frequency characteristics of the object are analyzed.

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