Building Vibration Induced by Percussive Piling

14th Asia Pacific Vibration Conference, Conference, 5-8 December 2011, The Hong Kong Polytechnic University

Building Vibration Induced by Percussive Piling Chi-tong WONG* Man-kit LEUNG* Wing-chi TANG* and Heung-ming CHOW* * Architectural Services Department, Hong Kong SAR Government, 38/F Queensway Government Offices, Hong Kong SAR E-mail: [email protected] [email protected]

Abstract

Due to the complex phenomenon of propagation of vibration from the ground through the foundation to the building, modelling and predicting building vibration due to piling operation is always a difficult task. Empirical formulae are therefore used to predict the vibration amplitude. However, few publications have been documented for the applicability of these empirical formulae in Hong Kong. This paper presents a prediction method and in-situ measurements for building vibration induced by installation of percussive steel H-piles from a construction site. The prediction makes use of calibrated Hong Kong soil data and the empirical method proposed by the US Federal Transit Administration. The results show that the approach provides a reasonable estimate of the building vibration due to percussive piling work. Key words: Building vibration; percussive piling; in-situ measurements

1. Introduction Vibration Vibration and noise induced by percussive piling are commonly considered as nuisance to the public in neighbouring areas. The vibration induced by piling operation from time to time attracts complaint from the public due to human discomfort felt in a building or cosmetic damage or structural distress caused to a building. For example, on 31 January 2011, when the foundation work was being carried out on a Wan Chai redevelopment site in Hong Kong, more than a dozen residents on the nearby six-storey building was asked by the police to evacuate, as many of them felt the shaking of the building and the furniture for at least twice in three days (The Standard, 1 February 2011). Therefore, though percussive steel H-pile is one of the most economical foundation types among various types of deep foundation if the site and geological condition permits, it is unfortunate that many projects avoid using this system just because of the fear of potential social resistance without carrying out an estimation of the genuine vibration effects beforehand. The vibration on the ground surface due to percussive piling has extensively been studied and documented. documented. However, the interaction interaction between the the ground and the foundation causes reduction in vibration amplitude. The amount of reduction depends on the building mass and stiffness of the foundation. A more massive building has lower response to the ground vibration. The vibration amplitude also decreases as the vibration energy propagates through the building to upper floors. However, in some cases, amplification of the vibration amplitude may occur due to resonance of the floor systems. Because there are so many factors to be considered in the estimate of building vibration due to piling operation, the propagation of vibration from the ground through the foundation to the building is a complex phenomenon that is difficult to model and predict accurately. Hence, empirical formulae are widely used to predict the vibration amplitude. However, few publications have been documented for the applicability of these empirical formulae in Hong Kong. This

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paper therefore presents a prediction method and the in-situ measurements for the building vibration induced by percussive piling work fro m a construction project of the Architectural Services Department of Hong Kong SAR Government.

2. Generation of Groundborne Vibrations When a hammer hits a pile, there is resistance at the pile toe which will generate vibration to the ground. The ground vibration can be divided into body waves and surface waves (Woods, 2004). The amount of groundborne vibration depends on three elements: input driving energy, attenuation rate and attenuation distance between the source and the receptor. It is further subdivided between the energy (resistance) generated from the pile shaft and toe, which depends on the pile and soil impedance (Massarsch and Fellenius, 2008). The rate of attenuation depends on the ground condition and the distance. Vibration level is affected by the penetration resistance, and will be increased when dense strata or boulder are encountered. In stiff or dense soils, smaller amount of energy is dissipated, as elastic deformation of the soil and penetration is small, resulting in higher groundborne vibration. In soft soils, most of the energy is used in overcoming soil friction and in advancing the pile, resulting in low level of ground vibration. The commonly way for quantifying ground vibration is Peak Particle Velocity Velocity (“PPV”). The measuring unit unit of PPV is in “mm/s”. “mm/s”. Extensive studies studies (Attewell and Farmer, 1973; Head and Jardine, 1992; Jongmans, 1996; Hope and Hiller, 2000; and Massarsch and Fellenius, 2008) have been carried out on correlating the ground vibration against different piling installation installation methods. methods. Most methods methods are based on energy approach and are basically basically empirical. There have been many such formulae in slightly different format developed over the years. One of the wisely used formulae for percussive piling was proposed by Hiller and Crabb (2000), as shown in Equation 1:

 W 1.3   r 

(1)

v  k p 

where W is the hammer energy; r is the slope distance (i.e. pile toe and the receiver, rather than the horizontal distance); and k p p is the most important parameter, which varies with different ground condition (and is greater in stiff, dense soils than in loose, soft soils). Though there are numerous values proposed for k p (e.g. BS 5228), there are no such data for Hong Kong soil. Wong et al (2011), based on a number of piling sites in Hong Kong, summarizes the relationship between average k p and equivalent N-value as shown in Figure 1. The result shows that the value of k p p increases together with the increases in equivalent SPT N-value. With the availability of SPT N-value, k p p can be determined readily for the prediction of PPV on the ground. Equation 1 was adopted in BS 5228 in predicting the ground vibration due to percussive piling, and BS 5228 Part 4 also specifies limits on the ground vibration. vibration. For residential premises, the limit on PPV for continuous vibration is 5mm/s and for transient vibration is 10mm/s. The PPV can also be expressed in terms of vibration velocity velocity level (L v) which is defined as shown in Equation 2 (Harris Miller, 2006):

 v    v ref 

(2)

L v  20  log10 

where Lv is the velocity level in decibels, v is the PPV, and v ref is the reference velocity which is usually taken as 2.54x10 -5 mm/s (Harris Miller, 2006).

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Relationship betw een Average k p and Equivalent N 1.8 1.7 1.6 1.5 1.4

Avg. k p

Upper Limit

1.3 1.2 1.1 1.0 0.9 0.8 0.7

Mean k p value

0.6 0.5 0.4 0.3 0.2 0.1 0.0 0

20

40 60 Equivalent. N

80

100

Velodrome TKO

Bailey Street

Kwun Tong Swimming Pool

Cruise Terminal

Sun Yat Sen

Victoria Park Swimming Pool Complex

Fig. 1

1 20

Relationship of average k p versus Equivalent N-value

3. Vibration of Buildings The previous paragraph discusses the prediction of ground vibration due to percussive piling. However, However, occupants of a neighbouring neighbouring building are more concerned about the resulting building building vibration vibration due to the percussive piling. The limits limits specified by BS 5228 represent that for structural damage. However, far before structural damage, occupants will have experienced annoyance and discomfort well below such limits. BS 6472 gives detailed guidance on human response to vibration in buildings. For residential premises, human will start to feel vibration with magnitude of 0.3 mm/s and 1.0 mm/s for continuous vibration and transient vibration, respectively (Sarsby, 2000). When considering the effects of piling vibration on buildings, foundations are initially excited by the ground vibration. For a typical reinforced concrete floor, the fundamental resonance is usually in the range of 20-30 Hz. Amplification is negligible if the excitation frequency is well below that of the fundamental floor resonance. However, typical vibration produced by percussive piling is in the range of 10-30Hz, and hence the potential of amplification is not negligible. The prediction of building vibration is therefore even more difficult than for ground vibration. Most numerical approaches are still in the early stages of development. The approach presented by the US Federal Transit Administration Administration (FTA) (Harris Miller, 2006) is widely employed in the industry. The method basically follows that suggested in the Handbook of Urban Rail Noise and Vibration Control (Saurenman et al., 1982). It relies on a heuristic predictive model for predicting train-induced vibrations in buildings. As the method is devised for vibration from mass transit projects, it may not be entirely applicable for piling work. Yet it is difficult to find a handy method and there are no available numerical methods to compute the vibration. Hence, though the method is very crude, designers prefer this method, especially that it is very easy to use and able to give the

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estimate quickly. Hence, it was determined to validate its applicability in Hong Kong with the project site in this paper. One-third-octave analysis is commonly used to analyze the vibration signals. In such an analysis, the time domain vibration signal is passed through a series of band-pass filters whose upper and lower frequency bands are defined by the American National Standards Institute (ANSI, 2004). FTA’s method consists of adding a number of adjustments, including building coupling loss (Figure 2), transmission through the building and floor resonances, to the 1/3-octave band spectrum of the projected ground-surface vibration. For estimating floor-to-floor vibration attenuation, -2dB/floor (1-5 floors above ground) and -1dB/floor (5-10 floors above ground) are suggested. The FTA manual also points out that some floors may exhibit resonant behaviour, amplifying vibrations by up to 6dB. According to the Study Report for TCRP Project D-12 sponsored by FTA (Zapfe et al., 2009), there are a number of areas where there is less confidence in the data and assumptions. These areas include: (1) the attenuation of vibration as the vibration energy travels from the ground into the building foundation and then propagates throughout the building, and (2) the amplification resulting from resonances of floors and other structural elements. Hence, the current practice in the US is that the resulting predictions are augmented with a factor of safety to account for these uncertainties. An allowance of up to 5 dB is therefore commonly adopted (Zapfe et al., 2009).

Fig. 2 Building coupling loss (extracted from FTA 2006)

4. Case Study In-situ measurements in one project at Bailey Street, Hung Hom, Hong Kong (location plan in Figure 3) were carried out to validate the predicted vibration level using FTA method. Percussive steel H-piles were used as the foundation system in the project. Field measurements were performed on the site and the building nearby (Peninsula Square), during the installation of the steel H-piles. Peninsula Square is a high-rise commercial reinforced concrete building with piled foundation.

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Fig. 3 Location plan of Joint-User Joint-User Complex at Bailey Street

The following is the information of the pile at the time of measurements: Hammer weight = 16t Height of drop = 1.5m Pile size = 305×305×180kg/m Grade S460J0 H-pile Efficiency = 90% Depth of pile at final set = 54m below ground Distance of the building from the pile = 25m Ground vibration is measured using vibrograph (Figure 4), which houses triaxial geophones of sensitivity and frequency range of 0.127-254mm/s 0.127-254mm/s and 2-250 Hz, respectively. respectively. Histogram mode was used for recording ground vibration under piling operation. In order to have better contact between the triaxial geophones and the ground surface, a sand bag was put on top of the vibrograph during measurement. Fig. 4

Vibrograph.

5. Prediction and Verification of Building Vibration Typical frequency spectra of the measured velocity are shown in Figure 5. It can be observed that the dominated frequency due to percussive piling is around 10-20Hz. The spectral vibration magnitude corresponding to vertical direction is the largest one among the three orthogonal directions. However, the translational velocities should not be ignored when considering vibration problem due to piling operation. PPV taken as the vector s um of the three orthogonal components is therefore used in the measurement. Tables 1 and 2 summarize the mean value estimate and the upper limit estimate of the vibration level against the measured vibration levels respectively. There is no amplification due to floor resonance at span of G/F, as G/F slab is on-grade. The measured PPV is the mean values of the measured data. There are four cases in total. Case 1 considers the “mean k p” value without any allowance for the uncertainty, uncertainty, while Case 2 uses the same k p p value but with +5dB allowance for the uncertainty. For Case 3, the “upper limit of k p p” value is applied with no allowance for the uncertainty. Case 4 is same as Case 3 except allowing only +2dB instead of +5dB as the upper limit of k p p value has been chosen.

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Fig. 5

Typical Typical frequency frequency spectra spectra of measured

velocity induced by percussive piling (transverse PPV=1.28mm/s; vertical PPV=3.18mm/s; longitudinal PPV=1.14mm/s )

Table 1. Location

Mean value value estimate (building coupling loss=6dB)

Measured PPV (mm/s)

Case 1 (kp=1.0) Attenuation2dB per storey

Case 2 (kp=1.0) Attenuation2 dB per storey + 5dB (allowance)

1.4

2.3 mm/s(99dB)

2.3 mm/s(99dB)

Outside building

Attenuation / resonance (/+ dB) G/F

column

0.9

span

1.0

1/F

column

0.9

span

2.3

2/F

column

0.9

6 6 8 2 10

span

2.8

4

Table 2. Location Outside building

dB

PPV (mm/s)

93

1.1

93

1.1

91

0.9

97 89 95

Attenuation / resonance (/+ dB)

dB

PPV (mm/s)

1 1 3

98

2.0

98

2.0

96

1.6

1.8

3

102

3.2

0.7

5

94

1.3

1.4

1

100

2.5

The upper limit estimate (building (building coupling coupling loss=6dB) loss=6dB)

Measured PPV (mm/s)

Case 3 (kp=1.3) Attenuation2dB per storey

Case 4 (kp=1.3) Attenuation2 dB per storey + 2dB (allowance)

1.4

2.9 mm/s(101dB)

2.9 mm/s(101dB)

G/F

column

0.9

span

1.0

1/F

column

0.9

span

2.3

2/F

column span

Attenuation / resonance (/+ dB) 6

dB

PPV (mm/s)

95

1 .5

6 8

95

1.5

93

1 .2

2 10

99

0.9

91

2.8

4

97

1.9

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Attenuation / resonance (/+ dB) 4

dB

PPV (mm/s)

97

1.9

4 6

97

1.9

95

1.5

2.3

0

101

2.9

0 .9

8

93

1.2

2

99

2.3


6. Discussions In Case 1, the calculated PPVs are quite close to the measured data except mid-span of 2/F where the predicted vibration level is only half of the measured one. In Case 2, +5dB allowance is added to cater for the uncertainty in the reality. It is found that the large discrepancy between the calculated and the measured vibration level at mid-span of 2/F is greatly reduced. The relatively large uncertainty in the empirical parameter of k p p justifies an allowance of +5dB. In Case 3, where the upper limit of k p p is used, most of the estimated vibration levels are slightly larger than or equal to those measured except mid-span of 2/F. It is observed that the amplification of vibration level at mid-span of 2/F is quite large that +5dB allowance of uncertainty may not be enough if mean value of k p p is adopted (e.g. Case 2). However, the estimated vibration level in Case 4 is 3.2mm/s (102dB) if +5dB instead of +2dB is employed. In this case, the estimated vibration level (3.2mm/s) is slightly larger than the measured value (2.8mm/s), which is conservative. Therefore, it can be concluded that +5dB allowance is generally good enough to cover the uncertainty provided that the upper limit of k p p is used.

7. Conclusions The measured field data match quite well with the estimated results based on FTA method, if adequate allowance allowance has been made made for the uncertainty. uncertainty. It is concluded concluded that the approach suggested by FTA, although crude, provides a reasonable estimate of the building vibration due to percussive piling work. For the allowance of uncertainties, 0-5dB is well representing the uncertainty, provided that the upper limit of k p p (Figure 1) is used. In this particular case-study, the amplification of vibration level at mid-span of 2/F is relatively large, and the limit of +6dB suggested by the FTA manual may not be enough to cater for the amplification. More data should be collected for further investigation in this area.

References (1)

Amick,

H.

and

Gendreau,

M.,

Construction

vibrations

and

their

impact

on

vibration-sensitive facilities, Presented at the ASCE Construction Congress 6, Orlando, Florida, 22 February 2000 (2)

ANSI, Specification for octave-band and fractional-octave-band analog and digital filters, In S1.11-2004, American National Standards Institute, New York, 2004

(3)

Athanasopoulos, G.A. and Pelekis, P.C., Ground vibrations from sheetpile driving in urban environment: measurements, analysis and effects on buildings and occupants, Soil Dynamic and Earthquake Engineering, Volume 19, 2000, pp 371-87

(4)

Attewell, P.B. and Farmer, I.W., Attenuation of ground vibrations from pile driving, Ground Engineering, 6(4), 1973, pp. 26–9

(5)

BSI, BS 5228-2:2009 - Code of practice for noise and vibration control on construction and open sites – Part 2: Vibration, BSI, London, 2009

(6)

BSI, BS 6472-1:2008 – Guide to evaluation of human exposure to vibration in buildings-Part 1: Vibration sources other than blasting, BSI, London, 2008

(7)

BSI, BS 7385-1:1990 - Evaluation and measurement for vibration in buildings – Part 1: Guide for measurement of vibration and evaluation of their effects on buildings, BSI, London, 1990

(8)

BSI, BS 7385-2:1993 - Evaluation and measurement for vibration in buildings – Part 2: Guide to damage levels from groundborne vibration, BSI, London, 1993

(9)

Clough, G. W. and Chameau, J., Measured effects of vibratory sheet pile driving, Journal of the Geotechnical Engineering Division, ASCE, 106(GT10), 1980, pp. 1080 – 99

(10) Harris Miller, Miller & Hanson Inc., Transit noise and vibration impact assessment, Federal Transit Administration (FTA), (FTA), 2006. (11) Head, J.M. and Jardine, F.M., Construction industry research and information association

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(CIRIA) technical note 142 - groundborne vibrations arising from piling, CIRIA, London, 1992 (12) Hiller D. M. and Crabb G. I., Groundborne vibration caused by mechanized construction works, TRL Report 429, Transport Research Laboratory, Berkshire, 2000 (13) Hope, V.S. and Hiller, D.M., The prediction of groundborne vibration from percussive piling, Canadian Geotech. Journal, Volume 37, 2000, pp 700-11 (14) Jongmans D., Prediction of ground vibration caused by pile driving: a new methodology, Engineering Geology, Volume Volume 42, 1996, pp. 25-36 (15) Massarsch K. R. and Fellenius, B.H., Ground vibrations induced by impact pile driving, International Conference on Case Histories in Geotechnical Engineering, Arlington, Virginia, 12-18 August 2008 (16) Massarsch, K. R., Settlements and damage caused by construction-induced vibrations, Proceedings, Intern. Workshop Wave 2000, Bochum, Germany, 13–15 December 2000, pp. 299 – 315 (17) Mohamed, R. and Dobry, R., Settlements of cohesionless soils due to pile driving, Proceedings, 9th Southeast Asian Geotechnical Conference, Bangkok, Thailand, 1987, pp. 7-23 – 30 (18) Sarsby, R.W., Environmental geotechnics, Thomas Telford Ltd, London, 2000 (19) Saurenman H.J., Nelson J.T. and Wilson G.P., Handbook of urban rail noise and vibration control (Report UMTA-MA-06-0099-82-1) Wilson, Ihrig & Associates, Oakland, California, 1982 (20) Wiss, J.F., Construction vibrations: state-of-the art, Journal of the Geotechnical Engineering Division, ASCE, Volume 107(GT2), 1982, pp. 167-81 (21) Wong, C.T. Wong, M.K., Leung, M.K. and Tang, W.C, Groundborne vibration from percussive piling, To be presented at the 14th Asia Pacific Vibration Conference, Hong Kong Polytechnic University, 5-8 December 2011 (22) Woods, R.D. and Sharma V.M., Dynamic effects of pile installations on adjacent structures Balkema Publishers, Washington, DC, 2004 (23) Yeung, A.T., Tham, L.G., Yang J. and Li, K.S.V., Ground vibration induced by percussion piling, Proceedings of the 16th International Conference on Soil Mechanics and Geotechnical Engineering, Volume 4, 2005, pp. 2205-8 (24) Zapfe J.A., Saurenman H.J. and Fidell S.A., Contractor’s final report for TCRP project D-12 - groundborne noise and vibration in buildings caused by rail transit, Transportation Research Board, Washington, DC, 2009

Acknowledgements The authors would like to record their thanks to the Director of Architectural Services for her kind permission of publishing the paper. The authors would also like to record their thanks to the staff in Division One of the Structural Engineering Branch in the Architectural Services Department, Hong Kong SAR Government for their help in preparing the manuscript.

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Building Vibration Induced by Percussive Piling

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