Victor V. Krylov

Surface Acoustic Waves in Inhomogeneous Media

This monograph covers important problems caused by the interaction of different types of surface acoustic waves with surface inhomogeneities. The problem of surface acoustic wave interaction with periodic topographic gratings, widely used in filters and resonators, is given careful consideration. The most important results of surface wave scattering by local defects such as grooves, random roughness and elastic wedges are described. Different theoretical approaches and practical rules for solving the surface wave problems are also presented.

GENERATION OF GROUND VIBRATIONS BY SUPERFAST TRAINS

Ground vibrations generated by superfast trains are studied theoretically, taking into account the contribution of each sleeper of the track subjected to the action of the carriage wheel axles. It is shown that a very large increase in vibration level may occur if the train speed exceeds the velocity of Rayleigh surface waves in the ground, a situation which might arise, for example, with TGV passenger trains for which speeds over 500 km/h have been achieved on the experimental track in France. The results are illustrated by numerically calculated graphs of spatial distributions and frequency spectra of ground vibrations generated by trains moving with different speeds. Simple mitigation measures based on waveguide effects for ground vibrations are suggested.

Noise and vibration from high-speed trains

Presents the views of leading international experts on the current status of the problems of generation and propagation of noise and vibration from high-speed trains, and suggests possible ways of reducing their environmental impact.

Vibrational impact of high‐speed trains. I. Effect of track dynamics

The dramatic increase in speeds of modern passenger trains makes it important to consider the vibrational impact of such trains on the built environment. In the author’s earlier paper in which a quasistatic approach to the calculation of track deflection curves had been used [V. V. Krylov, Appl. Acoust. 44, 149–164 (1995)], it had been shown that a very large increase in generated ground vibration level (about 70 dB, as compared to conventional trains) may occur if train speed exceeds the velocity of Rayleigh surface waves in the ground. Such a situation might arise, for example, with French TGV trains for which speeds over 515 km/h have been achieved. The present paper investigates the effect of track bending waves propagating in the system track/ground on railway‐generated ground vibrations. It is shown that for train speeds approaching the minimal phase velocity of bending waves the level of generated ground vibrations is reduced. Theoretical results are illustrated by numerically calculated frequency ...

Calculation of Low-Frequency Ground Vibrations from Railway Trains

Understanding physical mechanisms of railway-induced groundvibrations is an essential prerequisite for reducing their impact on the built environment. In this paper the theory of generation of low-frequencygroundvibrations by moving trains in the framework of the quasi-static wheel pressure effect is developed using the Greens function formalism. Mechanical properties of the rail track and parameters of train and soil (including contact nonlinearity of the track-soil system) are taken into account in a theoretical model that considers generation of elastic waves by each sleeper of the track subjected to the action of all wheel axles. The analytical expressions have been derived and the numerical calculations have been carried out for the vibration spectra generated by trains. It is shown that these spectra depend strongly on the mechanical properties of soil, on the axle loads of the carriages and on the geometrical parameters of the track and train. Some practical methods are suggested to modify the spectra of railway-induced groundvibrations and to decrease their level in the chosen frequency intervals.

Rail movement and ground waves caused by high-speed trains approaching track-soil critical velocities

Abstract The increased speeds of modern trains are normally accompanied with increased transient movements of the rail and ground, which are especially high when train speeds approach some critical wave velocities in the track-ground system. These transient movements may cause large rail deflections, as well as structural vibrations and associated noise in nearby buildings. There are two main critical wave velocities in the track-ground system: the velocity of the Rayleigh surface wave in the ground and the minimum phase velocity of bending waves propagating in the track supported by ballast, the latter velocity being referred to as the track critical velocity. Both these velocities can be exceeded by modern high-speed trains, especially in the case of very soft soil where both critical velocities become very low. The discussion in this paper focuses on the effects of transient rail deflections on associated ground vibrations in the cases of train speeds approaching and exceeding Rayleigh wave and track critical velocities. The obtained theoretical results are illustrated by numerical calculations for TGV and Eurostar high-speed trains travelling along typical tracks built on soft soil.

Ground-borne vibration generated by vehicles crossing road humps and speed control cushions

Abstract Road humps and speed cushions are used to control vehicle speeds in residential areas. Ground-borne vibrations are produced when vehicles pass over these profiles and in some cases they can reach perceptible levels in adjacent buildings. This paper describes a study to assess the size and nature of these vibrations. Measurements of peak particle velocity have been taken alongside a selection of hump and cushion designs using a range of vehicles under controlled driving conditions. Vibration levels have been predicted using a vehicle model and related to measured values. Results from a previous study of the generation and transmission of traffic vibration in different soils have been used to provide guidance on the siting of these surface profiles to avoid disturbance. The research highlights the need to carefully consider the siting of these profiles especially on soft soils.

Harmonic generation and parametric mixing in wedge acoustic waves

Abstract The first theoretical consideration of nonlinear effects in wedge acoustic waves is given. The theory is restricted to the case of antisymmetric wedge modes propagating along the tip of a sharp-angle isotropic solid wedge. The nonlinear wave equation and corresponding tip conditions are derived and then solved using the geometrical-acoustic approach to elastic wedge propagation problems (Krylov, Akust. Zh. 35, 294 (1989)). It is shown that the lowest order of nonlinearity in this equation is cubic. Analytical expressions are derived for the amplitude of the third harmonic as well as for the amplitudes of the wedge waves with “sum” 2 ω 1 + ω 2 and “difference” 2 ω 1 − ω 2 frequencies. Numerical calculations carried out for several low-order wedge modes show a strong dependence of the growth parameter on the integrals describing the overlap of the mode-distributions with depth for different frequencies. The most interesting results have been obtained in the case of generation of waves with “difference” frequencies. Numerical calculations of the growth parameter as a function of the frequency ratio l = ω 3 / ω 1 show strong resonance behaviour around the value l = 1 corresponding to maximum growth rate. Comparison of the theoretical results with existing experiments (Adler et al., IEEE Trans. SU26, 345 (1979)) shows good qualitative agreement.

Flexural edge waves and Comments on "A new bending wave solution for the classical plate equation" [J. Acoust. Soc. Am. 104, 2220-2222 (1998)]

A brief review is presented of the theory of flexural edge waves, first predicted in 1960 by Yu K. Konenkov using Kirchhoff plate theory. It is demonstrated that the flexural edge wave is also predicted by Mindlin’s plate theory, and that the prediction agrees with measured data. It is noted that the edge wave was erroneously presented as a new type of bending wave solution in a recently published paper in this journal.

Contamination of indoor air by toxic soil vapours: the effects of subfloor ventilation and other protective measures

A steady-state analytical model is derived for estimating the concentration of vapour-phase contaminants in indoor air in houses with subfloor voids, given the contaminant concentration in bulk soil. The model includes the key mechanisms of transport and dispersion—contaminant partitioning into the soil-vapour phase, molecular diffusion, suction flow, stack effect, and ventilation, including contaminant transport by ventilation flow between subfloor void and living space. Using the model, different construction styles are examined from the point of view of their resistance to ingress of soil gases. Model results indicate that indoor air concentration depends strongly on wind velocity and on geometrical parameters of void and living space. Worked examples for houses of different construction styles illustrate the effects of wind velocity and house parameters on the concentration of benzene in soil that would give rise to its maximum permissible concentration in indoor air. Brief consideration is also given to concrete raft foundations and clean cover systems.