A Methodology for Assessing Ground Borne Noise And
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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 Copyright © 2018 | EAA – HELINA | ISSN: 2226-5147 - 1321 - All rights reserved Euronoise 2018 - Conference Proceedings 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 - 1322 - Euronoise 2018 - Conference Proceedings 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) - 1323 - Euronoise 2018 - Conference Proceedings 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) - 1324 - Euronoise 2018 - Conference Proceedings 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) - 1325 - Euronoise 2018 - Conference Proceedings 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.