Theoretical treatment and design of vibration damping constructions in the upper path structure for underground railways

Abstract

Perspective vibration damping devices, applicable for underground conditions, are considered. The physical model of elastic damping designs for the upper structure of a railway is formulated and on its base the numerical analysis of their effectiveness for underground railways conditions is carried out. The possible realizations of a design as continuous elastic mats and separate elements (shock absorbers) are considered. In the second case, the arrangement of the damping elements under a ballast stratum and under the carrying elements of a rail path (cross ties, concrete blocks, etc.) is possible. General conclusions are following: the most critical frequency band for underground railways’ practice is an octave with mean geometric frequency 31.5 Hz; for correct choice of the vibration isolating measure a simulation of multi-unit oscillation system is needed; usually a two-unit system is more efficient than one-unit both for low and high frequencies; the most efficient mechanism for vibration reducing in 31–63-Hz frequency bands is elastic coefficient lowering and mass enhancing of a unit with maximal vibration levels; damping coefficient increase leads to vibration level reduction for the resonant frequency and weak influence on the amplitude far from the resonant frequency.