Earlier work on the study of frequency characteristics of thin-walled underground pipeline to obtain an equation for finding the natural frequencies of the straight sections of the pipeline, taking into account the parameter of the longitudinal force, the magnitude of internal pressure, coefficient of elastic resistance of the soil, the option of thin tubing and added mass of the soil. In this article, using the obtained equation, we study the influence of the length of the section of the pipeline laid in the soil with different physical-mechanical characteristics, and the effect of the parameter of the longitudinal compressive forces at the frequency of free oscillations of thin-walled straight pipeline under the action of various internal working pressure for pipes of different diameters with different wall thicknesses. On the basis of the design data defined in the derived formulae, is determined by the criterion of application of shell theory or the core theory for finding the natural frequencies of thin-walled underground pipelines of large diameter, depending on the length of the element. Simultaneously, the obtained expression allows to determine the critical force at which buckling occurs in the core of the theory («beam buckling»), as well as the formula to determine the critical force, from which buckling occurs by shell theory (flattening of the cross section). Based on these data, it is concluded that flattening the cross section of the pipeline will occur when the force is at times less than required for the formation of «arch release», and consequently to ensure the reliability of underground thin-walled large diameter pipeline should be the first thing to check for resistance on the shell theory.

Sound environment is an essential sensory stimuli influencing on the all functional systems of the body. The nature of this influence depends not only on the volume, but also on the whole complex of factors affecting the subjective perception of sound. The article describes the effect of different noise and music stimuli on health and functional state of the human body, the importance of noise sensitivity due to the severity of the composition offunctional changes.

This paper is based on the equation obtained earlier by V.G. Sokolov to find the frequencies of natural vibrations of straight sections of large-diameter pipelines. In this work, to take into account the effect of hydrostatic pressure on the pipeline wall from oil flowing at different speeds, the solution obtained by M.A. Ilgamov and A.S. Volmyr is used. At the same time, the effect of a stationary fluid flow on the pipeline wall is taken into account in the equation written in forces for the last term of the normal component of inertia forces. The resulting modified equation allows determining the frequency characteristics of the pipeline both according to the rod theory (without taking into account the deformation of the cross section) and according to the theory of shells (taking into account the deformation of the cross section).

This paper raises the question of a new approach to the dynamic calculation of thin-walled underground pipelines of large diameter, which is based on the application of the Vlasov-Novozhilov half-time theory of medium-bend shells, which ignores the M1 moments that bend the cylindrical shell in the longitudinal direction, since they are much smaller than the M2 moments that bend it in the transverse direction. The resolving equation for this approach is a homogeneous 4th-order differential equation that uses two boundary conditions at each end to solve it. The resulting equation takes into account the parameter of the longitudinal force, the value of the internal pressure, the coefficient of elastic resistance of the soil, the parameter of thinness, as well as the attached mass of the soil. Based on the data obtained from the derived formulas, the frequency characteristics of thin-walled underground pipelines of large diameter with different physical and mechanical properties are determined depending on the length of the element, as well as ground conditions. It is established that the minimum frequencies for the shell form of vibrations in various ground conditions are realized only for steel pipes, and for polyethylene and fiberglass pipes, depending on the coefficient of elastic resistance of the soil, they can be realized both in the rod and shell form. At the same time, using a dynamic stability criterion, derived expressions to determine the critical external pressure, taking into account the pipe length and the number of half waves in the cross section in which there is a constructive denial of the pipeline. Based on this expression, a formula for determining the critical depth of laying for thin-walled pipelines is obtained.

The problem of finding the natural frequencies of thin-walled underground oil pipelines is solved, based on the application of a semi-momentless theory of cylindrical shells of medium bending, in which bending moments in the longitudinal direction are not taken into account in view of their smallness compared with moments acting in the transverse direction. The solution to this approach is a fourth-order homogeneous differential equation satisfying the boundary conditions of articulation at each end. This equation includes the parameters of the length, internal pressure, thinness of the pipeline, as well as the values of the coefficient of elastic resistance of the soil, the attached mass of the soil and the attached mass of the flowing oil. Based on the data obtained by the derived formulas, the frequency characteristics of large-diameter thin-walled underground oil pipelines are determined depending on the length of the element, as well as on the soil conditions. It has been established that the minimum frequencies are realized for shell modes of vibration with a length parameter of the pipeline section (the ratio of the length of the section to the radius) not exceeding 13. A formula is derived that allows one to determine the boundary between the use of the rod and shell theory for calculating pipelines for dynamic effects. Using the dynamic stability criterion, in which the frequency of natural oscillations vanishes, expressions are derived that allow one to determine the external critical pressure on the wall of the pipeline, which takes into account the length of the pipeline, as well as the number of half waves in the transverse and longitudinal directions, in which the pipeline goes into emergency condition.