Review article

The article considers the problem of determination of the spectrum of frequencies and forms of natural oscillations for an underground main pipeline of large diameter (> 1000 mm), taking into account the damper. The problem solution is constructed using the theory of cylindrical shells of medium bending. The damping effect of the soil is taken into account in the radial component of the inertia forces and is based on the kinematic theory regarding the assumption of the medium resistance proportional to the speed of the median surface element moving in this medium. There have been obtained results, the analysis of which shows that the influence of the damper makes a significant correction in determining the frequencies in the direction of their decrease. The higher the dynamic viscosity of the soil, the more significant is the discrepancy of the results between ωmn и ω* mn. With an increase in the dynamic viscosity coefficient, the frequency decreases, and at certain values the damping coefficient dm = ωmn, which is the boundary of the transition from periodic to aperiodic oscillations, that is, there is no oscillatory process.