Mitigation solutions for low frequency structure borne noise. Stockholm, December 11, 2012 Presented by Hamid Masoumi

Transcription

1 Mitigation solutions for low frequency structure borne noise Stockhol, Deceber 11, 2012 Presented by Haid Masoui

2 Introduction Traffic generates vibrations: In the ground at 10 to 40 Hz Slab natural frequencies at 12 to 16 Hz Results in a vibration aplification by a factor of 10 Measured at point A Measured at point B B A Passage of a truck at a speed v = 50 k/h, (after Pyl et al. 2004) Brussels, 5 March,

3 Structure-borne noise Siplified equation (conservative): L p = L v5-22 [db] Vibration level at floor or wall L v5 = 20 log 10 (v/v 0 ) (v 0 = 1E-9 /s) Sound pressure L p = 20 log 10 (p/p 0 ) (p 0 = 2E-5 Pa) L pa = (A-weighted L p ) < L A,ax = 40 [db] residential area Stockhol, 11 Deceber,

4 Vibration transission echanis The ain proble is decoposed to: 1. Road-Ground interaction: Road type Ground type Vehicle type V 5 2. Transissibility: Ground type V 0 V 1 V 2 V 3 V 4 3. Ground-foundation interaction: Ground type Foundation type 4. Building response: Wall/floor type Stockhol, 11 Deceber,

5 TF GG [db] TF FB [db] Vibration transission echanis Road-Ground transfer function V 5 TF RG = L v1 - L v0 Transissibility in the ground V 0 V 1 V 2 V 3 V 4 TF GG = L v3 - L v1 Ground-foundation transfer function TF GF = L v4 - L v3 Transissibility in the building TF FB = L v5 - L v4 L v5 = L v0 + TF RG + TF GG + TF GF + TF FB Or L v5 = L v1 + TF GG + TF GF + TF FB Vibration level L v [db] = 20 log 10 (v/v 0 ) (v 0 = 1E-9 /s) f [Hz] f [Hz] Stockhol, 11 Deceber,

6 Traffic-induced vibration itigation Vibrations at a frequency range fro 10 to 30 Hz The itigation syste : (1) reducing the vibration aplitude by iproving the soil around the vibration source, and diffracting the generated waves by trenches and barrier, (2) shifting the frequency content of the induced vibrations and, reducing the energy of the transitted wave by isolating barrier. Brussels, March 5,

7 Vibration itigation systes The itigation syste : reducing the vibration aplitude reducing the energy of the transitted wave shifting the frequency content of the induced vibrations Active isolation by soil iproving Isolation in transission path by barriers Passive isolation by isolating panel Stockhol, 11 Deceber,

8 Vibration itigation by isolating barrier Efficiency paraeters: R b The height ratio H b / λ R The width ratio W b / λ R A The distance ratio R b / λ R where, λ R = C R / f H b W b H b / λ R > 2,0 W b / λ R > 0,2 A r = u A-after / u A-before 0,25 R b / λ R < 1,5 Brussels, March 5,

9 Isolating barrier echanis Reduction factor: The ipedance ratio: The travelling tie: A u / u r t d b t i C b b C b b C A r s s 1 t b A r 1 1 ( ) 1-D bar eleent odel Brussels, March 5,

10 as: 1-D odeling of isolating echanis Z concrete ZEPS 3200 Z concrete Ztire shred Z concrete Zsoil One-layer barrier Multi-layer barrier Brussels, March 5,

11 Nuerical odeling of isolating barrier Before isolating barrier installation After isolating barrier installation ILoss db = 20 Log 10 ( PPV iso PPV non iso ) Stockhol, 11 Deceber,

12 Description of work Validation of itigation solutions for low frequency structure borne noise Selecting a reference site and in-situ easureent Nuerical odeling for pre-diensioning Validation of prediction odel by eans of Scaled test bench easureent with different barrier type will be exained: Concrete barrier Concrete-EPS-Concrete barrier Stockhol, 11 Deceber,

13 Vibration itigation by isolating barrier In-situ easureent L v0 or L v1 and L v3 Building response L v5 > L v (adissible) Ground transissibility before isolating TF GG = L v3 L v1 Ground properties C s, ρ s Target frequency band Pre-diensioning of isolating barrier H b, W b, R b By nuerical siulation Validation of the proposed odel by sall-scale test And tuning the nuerical odeling Selection of barrier diensions H b, W b, R b Stockhol, 11 Deceber,

14 Measureent at the selected site Location A: bus over a speed table V 1 V 2 V 3 V 4 Stockhol, 11 Deceber,

15 Measureent at the selected site Location B: bus over a road joint V 1 V 2 V 3 V 4 Stockhol, 11 Deceber,

16 Reference site The soil has a Brussels foration with gray fine sand, lie, and lie sandstone. Stockhol, 11 Deceber,

17 Measureent at the selected site Transissibility through the propagation path (TF GG = L v3 - L v1 ) Ground conditions : inhoogeneity; pipes; sewers; obstacles Location A Location B Stockhol, 11 Deceber,

18 Measureent at the selected site Ground-foundation interaction Soil properties Foundation type Location A Location B Stockhol, 11 Deceber,

19 Prediensioning Using a coupled FEM-BEM odel R b H b W b Case 1 Case 2 W p = 0,60 W p = 0,80 Concrete barrier H p = 9,0 H p = 12,0 R p = 2,25 R p = 3,0 Concrete-EPS-Concrete barrier W p = 3x0,6 W p = 3x0,8 H p = 6,0 H p = 8,0 R p = 2,25 R p = 3,0 Stockhol, 11 Deceber,

20 Pre-diensioning Using a coupled FEM-BEM odel Stockhol, 11 Deceber,

21 Experiental test bench Stockhol, 11 Deceber,

22 Experiental test bench Measureent setup Stockhol, 11 Deceber,

23 Experiental test bench Soil treatent Sand pluviation Density test Ipedance test SASW test Brussels, March 5,

24 Experiental test bench Measureent setup Excitation with a shaker A rando haronic vibration Frequency range fro 100 to 900 Hz Acceleration 100 v/g Brussels, March 5,

25 Experiental test bench Concrete barrier Concrete-EPS-Concrete barrier Stockhol, 11 Deceber,

26 Experiental validation by sall-scale test Geoetrically Scaled by factor of N Frequency band Concrete barrier Concrete-EPS-Concrete barrier Sall-scale odel f = Hz W = 0,04 H = 0,60 R = 0,15 W = 0,12 H = 0,4 R = 0,15 Full-scale N = 15 f p = 6,7 73 Hz W p = 0,60 H p = 9,0 R p = 2,25 W p = 3x0,6 H p = 6,0 R p = 2,25 Full-scale N = 20 f p = 5,0 55 Hz W p = 0,80 H p = 12,0 R p = 3,0 W p = 3x0,8 H p = 8,0 R p = 3,0 denotes to sall-scale odel p denotes to full-scale prototype N is the geoetrical scale factor Stockhol, 11 Deceber,

27 Experiental validation by sall-scale test Sall-scale test Frequency band f [Hz] Wavelength λ R [] concrete barrier H b = 0,60 [] Depth ratio H b λ R [-] W b = 0,04 [] Width ratio W b λ R [-] concrete-eps-concrete barrier H b = 0,40 [] Depth ratio H b λ R [-] W b = 0,12 [] Width ratio W b λ R [-] ,5 1,2 0,08 0,80 0, ,25 2,4 0,16 1,60 0, ,167 3,6 0,24 2,40 0, ,125 4,8 0,32 3,20 0, ,1 6,0 0,40 4,0 1,20 Stockhol, 11 Deceber,

28 Experiental validation by sall-scale test Sall-scale test Frequency band f [Hz] Full-scale test N=15 Frequency band f p [Hz] Full-scale test N=20 Frequency band f p [Hz] , , ,3-46, , , Stockhol, 11 Deceber,

29 Experiental validation by sall-scale test Concrete barrier Concrete-EPS-Concrete barrier Nuerical Experiental Stockhol, 11 Deceber,

30 Experiental validation by sall-scale test Mean value of insertion loss over the points behind the barrier: x ILoss db = 1/(x 2 x 1 ) 2 ILoss dx x 1 Concrete barrier Concrete-EPS-concrete barrier Stockhol, 11 Deceber,

31 Conclusion Isolating barriers are introduced as a solution for traffic-induced vibration itigation. A practical solution has been proposed for reducing the structure-borne noise in building. A nuerical siulation is proposed for barrier design and evaluation of their efficiencies. Results of nuerical siulation have been successfully validated by eans of experiental sall-scale test. Brussels, 5 March,