Reducing railway-induced ground-borne vibration by using open trenches and soft-filled barriers

Abstract

A trench can act as a barrier to ground vibration and is a potential mitigation measure for low frequency vibration induced by surface railways. However, to be effective at very low frequencies the depth required becomes impractical. Nevertheless, for soil with a layered structure in the top few metres, if a trench can be arranged to cut through the upper, soft layer of soil, it can be effective in reducing the most important components of vibration from the trains. This study considers the possibility of using such a realistically feasible solution.Barriers containing a soft fill material are also considered. The study uses coupled finite element / boundary element models expressed in terms of the axial wavenumber. It is found to be important to include the track in the model as this determines how the load is distributed at the soil's surface which significantly affects the insertion loss of the barrier. Calculations are presented for a range of typical layered grounds in which the depth of the upper soil layer is varied. Variations in the width and depth of the trench or barrier are also considered. The results show that, in all ground conditions considered, the notional rectangular open trench performs best. The depth is the most important parameter whereas the width has only a small influence on its performance. More practical arrangements are also considered in which the 2 sides of the trench are angled. Barriers consisting of a soft fill material are shown to be much less effective than an open trench but still have some potential benefit. It is found that the stiffness of the barrier material and not its impedance is the most important material parameter.

Modelling, simulation and evaluation of ground vibration caused by rail vehicles

“…A similar model was used by Jin et al [114] to represent a metro tunnel and comparisons were made with field measurements. Coupled 2.5D FE-BE models were also applied to surface railways in [115][116][117][118][119][120]. In [121] a 2.5D model was developed based on the method of fundamental solutions coupled to the finite element method (MFS-FEM) and in [122] the finite element method was coupled with a scaled boundary finite element method (FEM-SBFEM).…”

“…Mitigation measures can first be proposed for the track and the soil. Trenches and isolating screens were firstly suggested to isolate railway-induced vibration at high frequencies [120,[163][164][165]. The required depth is calculated in terms of the Rayleigh wavelength: a trench or a barrier is therefore invisible for long wavelength or low frequency vibration.…”

Mitigation of Traffic Induced Vibration Using Geocell Inclusions

“…The open trench approach was found the first and efficient approach for the mitigation of vibration in active and passive methods (Woods, 1968). However, to prevent the instability of sidewalls of an open trench, it was filled with different geo-materials (Thompson et al, 2016). The bentonite, water, concrete, soil and bentonite mixture, and EPS (expanded polystyrene) geofoam were the examples of such materials.…”

Model for predicting the vibrations of historical timber buildings due to traffic loads and its experimental validation

“…Ulgen et al 30 studied the foundation design and vibration isolation of a high-precision instrument subjected to ground-borne vibrations. Thompson et al 31 discussed reducing railway-induced ground-borne vibration by using open trenches and soft-filled barriers.…”