A Methodology for Assessing Ground Borne Noise And

A Methodology for Assessing Ground Borne Noise and Vibration Transfer Functions “Tunnel wall-Soil surface” for Metropolitan Rail Networks using the TBM Muck Train as a linear source: Measurements Campaign in the extension of Athens Metro Line 3 towards Piraeus

Vassiliki Zafiropoulou Dr. Researcher Laboratory of Transportation Environmental Acoustics (L.T.E.A.), Faculty of the Civil Engineering, University of Thessaly, Volos, Greece Konstantinos Vogiatzis Associate Professor, Laboratory of Transportation Environmental Acoustics (L.T.E.A.), Faculty of the Civil Engineering, University of Thessaly, Volos, Greece. Haralampos Mouzakis Assistant Professor, National Technical University of Athens, Greece.

Summary Attiko Metro S.A., in view of the further development of the Athens Metro network, has fully initiated the new extension of 7.6 km, for line 3 “Haidari to Piraeus Dimotiko Theatre” towards “University of Piraeus” (forestation), connecting the major Piraeus Port with “Eleftherios Venizelos” International Airport. During the operation of this major urban subway rail transit system, vibrations are expected to be generated when transmitted through the soil and cause vibrations in nearby buildings. In urban areas, these vibrations are a consequence of the vehicle forces acting from the wheels onto the track in local defects. The transmission of ground-borne vibrations from subway rail transit systems in a building is mainly governed by the transfer function (TF) of vibration diffusion from the tunnel wall or invert towards the soil surface in the façade of the given protected building. Therefore at the early stages of a vibration assessment, it is necessary to complete a rigorous and detailed analysis in the basis of a detailed finite element calculation. During the construction of the extension of Athens Metro to Piraeus a methodology was proposed and already tested in situ in order to determine the necessary TF of the rail vibration diffusion inside the given geological media demonstrating the vibration attenuation values in 1/3 octave band analysis. This paper presents the metrological methodology of the relevant measurements campaign and analyses the findings in several sections of the TBM tunnel using as a linear source the TBM muck train and ensuring simultaneous recordings both in tunnel wall and the soil surface. This metrological approach is very important in order to ensure a high accurate estimation of the expected vibration and ground borne noise levels in the façade of each receptor, during operation, and assess possible negative effects on local communities from the metropolitan railway–induced ground vibrations.

PACS no. xx.xx.Nn, xx.xx.Nn

1. Introduction1 locations (location codes: 3-01, 3-51, 3-52, 3-53 respectively) in order that the suitable mitigation The construction of Line 3 extension from “Aghia measures, such as floating slabs, should be taken. Marina” to “Piraeus” constitutes one of the most For the vibration measurements during tunnel significant construction projects in Athens. The new excavation, 10 passbys of the TBM’s muck train Line 3 extension to Piraeus has 7.6 km total length (Tunnel Boring Machine) were used as a linear and is constituted by 6 modern Metro Stations source of vibration, were executed using suitable (Aghia Varvara, Korydallos, Nikaia, Maniatika, triaxial accelerometers in order to assess the Piraeus, Dimotiko Theatro) [1]. The Metro diffusion of vibration and ground borne noise and Extension to Piraeus will serve approximately evaluate the expected effects using an appropriate 132,000 passengers on a daily basis, while the and calibrated Finite Element Model (FEM). distance between the Port and the International Wilcoxon accelerometers of increase sensitivity Airport will be covered by the Metro in just 45 were mounted simultaneously at the tunnel wall (or minutes. Additionally, once the Metro becomes invert) and on the ground surface in the closest operational, the number of vehicles will be reduced building façade and/or within the basement in by approximately 23,000 on a daily basis, leading to residential uses where adverse complaints were a respective daily reduction in CO2 by 120 tn. expressed by the inhabitants in order to form the appropriate Transfer Function (TF) to be used in the FEM. The measured parameters were the following: . Acceleration time series (mm/ s2) . 1/ 3 octave band analysis from 1 to 100 Hz

2.1. Permissible vibration limits

To determine the higher limits of the peak particle velocity (PPV) as a result of the vibrations generated by the construction works that affects the buildings, constructions and generally areas in the region of works, the Contractor should comply with the upper limits of PPV in z direction given in the table I below:

Control receptor Peak particle velocity PPV(z) 0.2 mm/sec Monuments, (At the base of the Figure 1. Line 3 Extension to Piraeus archaeological findings, monument, ancient Exhibits in exhibits, on the floor 2. Vibration measurements during the archaeological or on the wall of the operation of muck train as a linear Museums etc. source building) Special buildings Apart from the positive consequences of the subway (E.g. hospitals, theatres, schools, libraries, network construction and operation as described 0,5 mm/sec concert halls, audience above, the adverse complaints of residents owing to rooms) the ground borne noise and vibration during the 5 mm/sec for metro construction is an important problem that Other buildings continuous vibration should be encountered especially in crossover (Classification 10 mm/sec for locations (CO) of the metro line as per the relevant according to ISO 4866) intermittent Noise & Vibration (N&V) study executed within the vibrations Environmental Impact Assessment Study (EIA) of Table I. Permissible limits of vibration the project [2]. For this purpose, noise and vibration measurements were performed in turnout/ crossover

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Maximum vibration velocity limits were also determined in the frequency range defined in DIN 4150 (Part 3), as follows [3]:

. For the foundation: f ≤ 50 Hz at 3 mm/sec

50< f ≤ 100 Hz at 8 mm/sec . For the upper floors: 8 mm/sec for all frequencies.

2.2. Results of vibration measurements

Measurements were executed in 4 crossover locations at (a) Aghia Varvara: crossovers 3-01 and 3-51, and (b) Korydallos: crossovers 3-52 and 3-53). Peak particle velocity (PPV) was then calculated and after the 1/3 octave analysis the relevant TF was assessed for each location. In the following figures the relevant measurement locations and the corresponding vibration Transfer Functions (TFs) are presented.

Figure 3. Vibration velocity level at tunnel wall (muck train operation) in Aghia Varvara location (CO 3-01, 3- 51)

Receptor

Figure 2. Measurement location in Aghia Varvara: (CO

3-01 and 3-51)

Figure 4. Vibration velocity level on the soil surface (muck train operation) in Aghia Varvara location (CO 3- 01, 3-51)

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Figure 5. Transfer Function (TF) between the soil surface Figure 7. Vibration velocity level on the tunnel wall and the tunnel wall (muck train operation) in Aghia (muck train operation) in Korydallos location (CO 3-52, 3-53) Varvara location (CO 3-01, 3-51)

Measurement

location

Figure 8. Vibration velocity level on the soil surface Figure 6. Measurement location in Korydallos location (muck train operation) in Korydallos location (CO 3-52, (CO 3-52 and 3-53) 3-53)

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Figure 9. Vibration velocity level (muck train operation) Figure 11. Transfer Function (TF) between the basement on the soil surface in basement (floor -1) in Korydallos and the tunnel wall (muck train operation) in Korydallos location (CO 3-52, 3-53) location (CO 3-52, 3-53)

3. Finite Element Model (FEM)

The prediction of ground borne noise and vibration

levels in nearby buildings consists of the following steps [4], [5]: . finite element modeling of the tunnel section type located in the considered section, including the adequate soil stiffness and the wheel-rail system characteristics, in order to calculate the tunnel wall vibration levels generated by the

wheel-rail contact excitation

. propagation of the vibration levels from the tunnel to nearby buildings through the ground . soil-structure coupling at basement levels . amplification of the vibration levels at some frequencies (due to resonances of walls and

floors) . calculation of noise generated in the rooms by

vibration of walls and floors.

In figure 15 hereafter the calculation process of vibration velocity is demonstrated. Figure 10. Transfer Function (TF) between the soil surface and the tunnel wall (muck train operation) in Korydallos location (CO 3-52, 3-53)

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TUNNEL WALL VIBRATION 

PROPAGATION THROUGH SOIL

 SOIL VIBRATION  COUPLING TO THE BUILDING VIBRATION  FOUNDATION VIBRATION



PROPAGATION THROUGH TYPICAL ATHENIAN BUILDING STRUCTURE 

FLOOR AND WALL VIBRATION 

SOUND RADIATION DUE TO VIBRATION

 PERCEPTIBLE VIBRATION - NOISE

Figure 13. Numerical simulation in crossover locations Figure 12. Transmission path graphic (number of nodes: 2823, number of elements: 3157, total number of parameters: 5658) For the finalization of the model, two numeric simulations were prepared in conditions of direct In order that the border conditions of the problem to fixation with and without the implementation of be properly captured, springs and dampers were floating slab at locations of crossovers (CO). In the used in the transverse and longitudinal direction at context of the worst scenario, the vibrations, the perimeter nodes of the model. The stiffness of generated from the tunnel invert were considered to the springs and the damping of the dampers for P and be diffused in the soil without decrease owing to S waves for ground categories 1 and 2 are shown in interface. For the calculation of the vibration the table below. velocity at tunnel invert, 1/3 octave band from 10 to 200 Hz was used. Subsequently, eigenvalue and Modulus Spring Spring Damping Damping eigenvector were calculated for every simulation. of Robustne Robustne index index For the calculations, the velocity of the railway was Elasticity ss ss considered 60 km/h and the vertical force at the 2 P kNs/m P kNs/m interface between wheel and rail was assumed equal kN/m S kN/m S kN/m to 25 N/Hz. In figure 16 the relevant cross section is 0.1x106 140000 929 93333 536 presented for above case of crossovers in direct fixation (DF). In the perimeter of the simulations, 0.8x106 1120000 2627 746667 1516 springs and dampers were mounted in order to avoid 1.09x106 1526000 3066 1017333 1770 reflections at the borders. The physical and Table II. Mechanical characteristics of grounds, for all mechanical characteristics of the materials that were crossover locations. used in the simulation of concrete are the following:

. Ε=3,2.x1010N/m2 4. The proposed type of floating slab . v=0.25 (FS) . ρ=25kN/m3 The vibration exceedances of permitted values in

turnout/ crossover locations lead to the need of implementing mitigation measures such as floating slabs. The recommended floating slab consists of a continuous reinforced concrete plate which rests on a layer of continuous rubber substrate type CDM-

DFMA-L6 consisting of 2 layers-43020

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CDM/10mm with wavy form with min thickness of Max level Min level Limit Turnout/ kdyn 10 mm and max 20 mm. For the elastic support of in dB(A) in dB(A) in dB(A) floating slab a layout containing continuous Aghia Varvara, elastomer layer beneath the entire surface of the 3-01 & 3-51, 26.3 11.9 3 floating slab was recommended that is expected to kdyn=16 MN/m yield the desired impairment of ground borne noise Aghia Varvara, 3-01 & 3-51, 29.6 12.7 and vibration. The elastic layer has a total thickness 3 kdyn=22 MN/m of 40 mm. Figure 17 hereafter indicates the Metsovou 10, recommended floating slab. 3-52 & 3-53, 27.3 25.0 3 kdyn=16 MN/m Metsovou 10, 40.0

3-52 & 3-53, 30.3 27.9 3 kdyn=22 MN/m Metsovou 11,

3-52 & 3-53, 27.1 25.2 3 kdyn=16 MN/m Metsovou 11,

3-52 & 3-53, 30.0 28.1 3 kdyn=22 MN/m Table IIΙ. Results of ground borne noise level in dB(A)

with the implementation of floating slab

6. Conclusions

The Line 3 Extension to Piraeus is one the most

substantial projects in Athens. The construction and Figure 14. The recommended floating slab constructed by the operation of the underground subway are CDM-DFMA-L6 40mm of width with lateral buffers CDM 97. expected to have a positive impact on the lives of inhabitants. Nevertheless, subway’s operation may 5. Estimation of ground borne noise and vibration in provoke adverse complaints owing to the ground the closest receptor borne noise and vibration generated from the tunnel during the metro operation. For this reason, According to the results described aforementioned, the mitigation measures should be taken implementation of floating slab in control locations mentioned (implementation of floating slabs) so as residents was considered mandatory. The implementation of the proposed and nearby constructions to be protected from floating slab in turnout/ crossover locations is estimated to ground borne noise and possible excitation decrease vibrations generated from subway’s operation. As it is respectively. In this project, the measurement results illustrated in the following table IIΙ, the levels of ground borne of ground borne vibration and the methodology for noise and vibration after the implementation of floating slabs the need of mounting of floating slabs were are within the statutory limits for all the control locations (Aghia analytically described for three control positions Varvara and Korydallos) examined. (Aghia Varvara, Korydallos and Amorgou). However, Attiko Metro decided not to implement a floating slab at Amorgou location supporting that this consideration was too conservative.

References [1] http://www.ametro.gr/ [2] K. E. Vogiatzis: Environmental ground borne noise and vibration protection of sensitive cultural receptors along the Athens Metro Extension to Piraeus. Science of Total Environment (2012), Vol. 439, 230-237. [3] German Standard DIN 4150–3:1999–02 Vibration in buildings—Part 3: effects on structures

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[4] K. E. Vogiatzis: Protection of the cultural heritage from underground Metro vibration & ground borne noise in Athens centre: The case of Kerameikos Archaeological Museum & Gazi Cultural centre. International Journal of Acoustics and Vibration (2012), Vol. 17, 59-72. [5] K. Vogiatzis, H. Mouzakis: Ground borne noise and Vibration transmitted from subway networks to multi- storey reinforced concrete buildings. Transport (2017), ISSN: 1648-4142 (Print) 1648-3480 (Online).

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