Years of successful participation in many vibration isolation projects, have meant a vast collection of knowledge related to the in-situ performance of RockBallast® and RockXolid® product lines. A collection of some of the most important reference papers has been assembled in the following.
The papers are available upon request. Please click here for further information.
Revised Requirements for Stiffness of Ballast Mats in New Norwegian Railway Lines
A. Brekke
Brekke & Strand akustikk a/s, Oslo, Norway
H. Gåsemyr
Norwegian National Rail Administration, Oslo, Norway
Abstract:
In the Oslo region new railway lines, which include many and long tunnels below dwelling areas, are now planned and constructed. All the tunnel tracks are ballasted tracks. Ballast mats are the preferred remedial actions for reduction of ground borne noise. In the paper the work which leads to revised requirements for ballast mats are presented. Ballast mats having a stiffness of Cdyn, 3 Hz=0.01 N/mm3 have been installed in the most critical sections of the new tunnels. The required thickness of ballast for this track is 550 mm between sleeper underside and ballast mat surface. In the paper the definition and measurement method for maximum structure borne noise levels are given. The paper also shortly presents the results of a social survey on annoyance from this kind of noise, the calculation methods for structure borne noise transmission, and a method for measuring the vibration transmission from the tunnels before the track is installed.
Mitigation of Ground Borne Noise in Rock Railway Tunnels. Part I: Track Design and Simulation
R. Cleave, C. Madshus & L. Grande
Department of Geomechanics, Norwegian Geotechnical Institute, Oslo, Norway
Arild Brekke & Karin Rothschild
Brekke & Strand akustikk a/s, Oslo, Norway
Abstract:
Railway traffic in shallow depth rock tunnels can give unacceptable levels of ground borne noise in buildings above the tunnel. For such a tunnel under construction in Norway the Norwegian Rail Administration (JBV), with the aim of designing the most cost effective track that satisfied the prescribed residential sound levels, commissioned a project involving full scale testing. Evaluation of various track designs was based upon the results of a numerical model of the wagon-track-tunnel system. This model and the corresponding input parameters are the focus of this first part of a two part paper; the second part concentrates on the full scale tests. The numerical model presented herein is a one-dimensional model of the suspended railcar, rail, sleeper, railway substructure (ballast, ballast mats and backfill) and tunnel floor. The model comprises mechanical mass-spring-damper elements and “geolayer” elements embodied by the one-dimensional wave equation. Verification against results from other contributors is presented, and the model is shown to give high quality results with a modicum of computation. The properties of the constituent track materials are also discussed in this paper, with particular attention paid to the in-situ stress conditions.
Mitigation of Ground Borne Noise in Rock Railway Tunnels. Part II: Full Scale Tests
R. Cleave, C. Madshus & L. Grande
Department of Geomechanics, Norwegian Geotechnical Institute, Oslo, Norway
Arild Brekke & Karin Rothschild
Brekke & Strand akustikk a/s, Oslo, Norway
Abstract:
Railway traffic in shallow depth rock tunnels can give unacceptable levels of ground borne noise in buildings above the tunnel. For such a tunnel under construction in Norway a project was commissioned by the Norwegian Rail Administration (JBV) to design the most cost effective track that satisfied the prescribed residential sound levels. A component of this project was a series of full-scale tests. This, the second part of a two-part paper, discusses these full scale tests and compares the measured results against those predicted by the simulation work of the first part of the paper. For each of the seven track substructures tested the acceleration of the rail, sleeper, tunnel floor and tunnel wall were recorded, in addition to the acceleration at various depths throughout the track substructure. Vibration and sound were also measured in the houses above the tunnel. The input to the entire system was via a fully laden freight wagon which had a dynamic excitation force applied to one axle. This force was excited by a hydraulic actuator which, operating under force control, delivered excitation in sweeps of one-third octave bands that covered the relevant frequency range. This paper presents the testing programme and corresponding results, and compares these results with the predictions of the companion paper.
