Grand Paris Express – Study of Vibration Propagation in the Ground

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Context & Issue

The Grand Paris Express embodies the ambitious vision of a constantly evolving metropolis. This flagship urban development project aims to transform the Paris region into an innovative, interconnected transport network.

However, the construction of this network will not be achieved without taking into account the concerns of local residents. Both the choice of track layout and the question of ground vibrations have to be carefully studied to limit disruption to local residents throughout the construction and operation of the new train lines.

Client / Enduser Benefits

Development of the rail transport network in an urban environment

This involves building new automatic metro lines and stations, as well as upgrading existing infrastructure.

Peace and quiet for residents

This includes careful selection of routes to minimize the impact on residential neighborhoods

Cost management with optimized sizing of solutions and track laying

The use of innovative technologies and sustainable materials for infrastructure construction are at the heart of track-laying processes to optimize lead times and investments.

The challenges for Vibratec

Mapping sensitive areas

Comprehensive selection of sensitive areas along the entirety of the new network..

Driving new standards

Definition of a set of target values that can be used as references on a national level.

Mastering project phases

Follow-up throughout all project phases (definition, specification and validation of solutions) in order to anticipate any problems and, if necessary, to identify responsibilities.

Vibration and structure-borne noise computation for residents living above future Grand Paris Express lines

The subject of vibrations produced by certain urban transport systems and transmitted to neighboring buildings is becoming a major concern. In common cases, the effects produced are a feeling of discomfort linked to :

the physical perception of vibrations applied to the human body or to building installations,
solid-borne noise re-emitted by the building’s structural elements.

The vibration levels emitted by a moving rail vehicle depend on a large number of parameters, such as :

Vibratory excitation applied to the track as the rolling stock passes (emission),
Soil properties in terms of vibration transmissibility (propagation),
Building vibration sensitivity (immission).

For transport systems using iron/rail rolling surfaces, excitation levels depend on the following parameters:

Rail and wheel irregularity levels,
Dynamic properties of the track.

It is generally accepted that anti-vibration track-laying systems are the most effective and economic solution.

Development points

#01 Identification of vibration hotspots (sensitive sites, representative buildings) and determination of the vibration source.

#02 Characterization of soil dynamic properties.

#03 Calculation of vibration and structure-borne noise levels for each zone identified as being at risk.

#04 Sizing of mitigation solutions to meet project targets.

#05 Calculation of vibration and structure-borne noise impact levels, including mitigation measures.

#06 Drawing up specifications for mitigation solutions.

#07 Verification of mitigation solution effectiveness: laboratory tests and/or after track manufacture.

#08 Diagnosis of the network in operation: maintenance assistance, inspections following complaints from residents.

Study and simulation of future vibrations

This study was carried out using the 2 following approaches:

Use of GroundVib software to determine the term ‘excitation sources’ at platform level, and initial calculations to identify potential critical points.
If necessary, and depending on the complexity of the situation (tunnel, viaduct, non-homogeneous ground, etc.), more detailed simulation with 2.5D or 3D modeling at the complex points identified. These simulations are carried out once the platform structures are defined, to provide a more accurate estimate of future vibration levels at critical points.

Railway