Documents disponibles écrits par cet auteur

Different approaches for estimating ground strains from pile driving vibrations at a buried archeological site / Scott J. Brandenberg in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 8 (Août 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 8 (Août 2009) . - pp. 1101–1112 Titre : Different approaches for estimating ground strains from pile driving vibrations at a buried archeological site Type de document : texte imprimé Auteurs : Scott J. Brandenberg, Auteur ; Joseph Coe, Auteur ; Robert L. Nigbor, Auteur Année de publication : 2009 Article en page(s) : pp. 1101–1112 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Vibration  Pile  driving  Archaeology  Wave  measurement  Foundation  construction Résumé : Ground strains were estimated from vibrations measured during pile driving operations at a buried, prehistoric archeological site to monitor potential construction impacts. Subsurface characteristics of the site were investigated using multiple cone penetration test (CPT) soundings and the shear wave velocity profile was measured using the seismic CPT method. Embedded geophones and surface accelerometers were then used to measure ground vibrations during pile driving. Displacement gradients were estimated from the vibrations using the following three methods: (1) the difference between adjacent displacements divided by sensor spacing; (2) peak particle velocity divided by depth-dependent wave velocity (i.e., at the depth where the sensor was placed); and (3) peak particle velocity divided by frequency-dependent wave velocity from a measured dispersion curve. Methods (1) and (3) agreed well, while method (2) caused errors that depended on depth of embedment of the sensors and distance from pile driving. Errors in (2) were attributed to a mismatch between the depth-dependent wave velocity and the wave velocity on the frequency band that carried the largest velocity pulse through the dispersive soil profile. Ground strains were related to displacement gradients based on theoretical solutions of harmonic body waves and Rayleigh waves in dispersive elastic media. The peak estimated ground strains were smaller than the threshold volumetric shear strain, but a few centimeters of settlement were nevertheless observed at the site. The spatial extent of the settlement is characterized using attenuation rules fit to the vibration data, and by calibration with a settlement gauge. Ground cracking and vertical offsets that could potentially mask the archaeological history of the site were neither observed nor predicted from the observed vibration amplitudes. Estimated impact on archeological interpretation of artifacts in their stratigraphic context was likely insignificant except in the immediate region where the piles were driven. This insight will assist in future planning at sites with similar subsurface stratigraphy. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000031 [article] Different approaches for estimating ground strains from pile driving vibrations at a buried archeological site [texte imprimé] / Scott J. Brandenberg, Auteur ; Joseph Coe, Auteur ; Robert L. Nigbor, Auteur . - 2009 . - pp. 1101–1112. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 8 (Août 2009) . - pp. 1101–1112 Mots-clés : Vibration  Pile  driving  Archaeology  Wave  measurement  Foundation  construction Résumé : Ground strains were estimated from vibrations measured during pile driving operations at a buried, prehistoric archeological site to monitor potential construction impacts. Subsurface characteristics of the site were investigated using multiple cone penetration test (CPT) soundings and the shear wave velocity profile was measured using the seismic CPT method. Embedded geophones and surface accelerometers were then used to measure ground vibrations during pile driving. Displacement gradients were estimated from the vibrations using the following three methods: (1) the difference between adjacent displacements divided by sensor spacing; (2) peak particle velocity divided by depth-dependent wave velocity (i.e., at the depth where the sensor was placed); and (3) peak particle velocity divided by frequency-dependent wave velocity from a measured dispersion curve. Methods (1) and (3) agreed well, while method (2) caused errors that depended on depth of embedment of the sensors and distance from pile driving. Errors in (2) were attributed to a mismatch between the depth-dependent wave velocity and the wave velocity on the frequency band that carried the largest velocity pulse through the dispersive soil profile. Ground strains were related to displacement gradients based on theoretical solutions of harmonic body waves and Rayleigh waves in dispersive elastic media. The peak estimated ground strains were smaller than the threshold volumetric shear strain, but a few centimeters of settlement were nevertheless observed at the site. The spatial extent of the settlement is characterized using attenuation rules fit to the vibration data, and by calibration with a settlement gauge. Ground cracking and vertical offsets that could potentially mask the archaeological history of the site were neither observed nor predicted from the observed vibration amplitudes. Estimated impact on archeological interpretation of artifacts in their stratigraphic context was likely insignificant except in the immediate region where the piles were driven. This insight will assist in future planning at sites with similar subsurface stratigraphy. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000031

Fast stacking and phase corrections of shear wave signals in a noisy environment / Scott J. Brandenberg in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°8 (Août 2008) . - pp. 1154–1165 Titre : Fast stacking and phase corrections of shear wave signals in a noisy environment Type de document : texte imprimé Auteurs : Scott J. Brandenberg, Auteur ; Kutter, Bruce L., Auteur ; Daniel W. Wilson, Auteur Année de publication : 2008 Article en page(s) : pp. 1154–1165 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Wave  velocity  Shear  waves  Soil  modulus  Soil-structure  interaction  Centrifuge  Piezoelectricity Résumé : Hardware, software, and analysis of transient response of sources and receivers are presented for a piezoelectric bender element system designed to measure shear wave velocities in noisy environments. Signal-to-noise ratio is improved by signal stacking, wherein data vectors from many pulses are summed. A new fast-stacking algorithm enables signal quality to be improved much more rapidly than conventional stacking. Conventional stacking is accomplished by repeatedly sending an excitation pulse to a source, waiting for the signal and secondary reflections to pass the receiver and then introducing a subsequent excitation pulse. Using conventional stacking, it is important to wait for the signal and secondary reflections to die out before exciting subsequent pulses. In the new fast-stacking algorithm, a varied interval between consecutive pulses is used so that high quality signals can be obtained even if consecutive pulses are excited in rapid succession. Transient behavior of soil–bender interaction was characterized using closed-form analytical solutions of single-degree-of-freedom oscillators, numerical solutions using a beam-on-springs method, and measurements from an array of bender elements in a sand model. The time delay caused by soil–bender interaction was calculated to be half of the natural period of the bender element, and this theoretical time delay was supported by experimental data. This system makes it feasible to rapidly collect accurate shear wave velocity information so that transient changes in shear wave velocity can be monitored even if background noise is large. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A8%2811 [...] [article] Fast stacking and phase corrections of shear wave signals in a noisy environment [texte imprimé] / Scott J. Brandenberg, Auteur ; Kutter, Bruce L., Auteur ; Daniel W. Wilson, Auteur . - 2008 . - pp. 1154–1165. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°8 (Août 2008) . - pp. 1154–1165 Mots-clés : Wave  velocity  Shear  waves  Soil  modulus  Soil-structure  interaction  Centrifuge  Piezoelectricity Résumé : Hardware, software, and analysis of transient response of sources and receivers are presented for a piezoelectric bender element system designed to measure shear wave velocities in noisy environments. Signal-to-noise ratio is improved by signal stacking, wherein data vectors from many pulses are summed. A new fast-stacking algorithm enables signal quality to be improved much more rapidly than conventional stacking. Conventional stacking is accomplished by repeatedly sending an excitation pulse to a source, waiting for the signal and secondary reflections to pass the receiver and then introducing a subsequent excitation pulse. Using conventional stacking, it is important to wait for the signal and secondary reflections to die out before exciting subsequent pulses. In the new fast-stacking algorithm, a varied interval between consecutive pulses is used so that high quality signals can be obtained even if consecutive pulses are excited in rapid succession. Transient behavior of soil–bender interaction was characterized using closed-form analytical solutions of single-degree-of-freedom oscillators, numerical solutions using a beam-on-springs method, and measurements from an array of bender elements in a sand model. The time delay caused by soil–bender interaction was calculated to be half of the natural period of the bender element, and this theoretical time delay was supported by experimental data. This system makes it feasible to rapidly collect accurate shear wave velocity information so that transient changes in shear wave velocity can be monitored even if background noise is large. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A8%2811 [...]

Influence of underlying weak soil on passive earth pressure in cohesionless deposits / Scott J. Brandenberg in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 3 (Mars 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 3 (Mars 2011) . - pp. 273-278 Titre : Influence of underlying weak soil on passive earth pressure in cohesionless deposits Type de document : texte imprimé Auteurs : Scott J. Brandenberg, Auteur ; Pirooz Kashighandi, Auteur Année de publication : 2011 Article en page(s) : pp. 273-278 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Passive  pressure  Earthquakes  Lateral  spreading  Liquefaction Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Finite-element simulations demonstrate the influence of underlying weak soil on mobilization of passive pressures in cohesionless deposits. Traditional passive earth pressure theories with typical angles of interface friction may overestimate passive forces in such cases. Simple analytical models that incorporate the underlying weak soil using traditional passive earth pressure concepts are shown to agree reasonably with the finite-element simulations. The studies presented herein are relevant for cases in which cohesionless soil deposits overlie soft clay, liquefiable sand, or other weak layers. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i3/p273_s1?isAuthorized=no [article] Influence of underlying weak soil on passive earth pressure in cohesionless deposits [texte imprimé] / Scott J. Brandenberg, Auteur ; Pirooz Kashighandi, Auteur . - 2011 . - pp. 273-278. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 3 (Mars 2011) . - pp. 273-278 Mots-clés : Passive  pressure  Earthquakes  Lateral  spreading  Liquefaction Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : Finite-element simulations demonstrate the influence of underlying weak soil on mobilization of passive pressures in cohesionless deposits. Traditional passive earth pressure theories with typical angles of interface friction may overestimate passive forces in such cases. Simple analytical models that incorporate the underlying weak soil using traditional passive earth pressure concepts are shown to agree reasonably with the finite-element simulations. The studies presented herein are relevant for cases in which cohesionless soil deposits overlie soft clay, liquefiable sand, or other weak layers. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i3/p273_s1?isAuthorized=no

p-Wave reflection imaging of submerged soil models using ultrasound / Joseph Coe in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 10 (Octobre 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 10 (Octobre 2010) . - pp. 1358-1367 Titre : p-Wave reflection imaging of submerged soil models using ultrasound Type de document : texte imprimé Auteurs : Joseph Coe, Auteur ; Scott J. Brandenberg, Auteur Année de publication : 2010 Article en page(s) : pp. 1358-1367 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Soils  Ultrasonic  methods  Transfer  functions  Transducers  Imaging  techniques  Signal  processing  Submerging  Reflection  Compression  waves Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : An ultrasonic p-wave reflection imaging system is used to noninvasively image submerged soil models with embedded anomalies and complex geometric layer contacts. The ultrasonic transducers emit compressive waves into water that subsequently transmit into the underlying soil, and measurements of the reflections are used to construct the images. The properties of the transducers and data acquisition hardware and software are explained. Fast signal stacking is used to improve signal-to-noise ratio and provide clearer images. Transducer directivity is explained as a wave passage effect, and transfer functions are derived for square and circular transducers to quantify directivity. The transfer functions agree reasonably with measured amplitude data. The cause of errors in the imaged position of dipping reflectors is explained, and a Kirchhoff migration algorithm is implemented to correct these errors. A soil model consisting of embedded high- and low-impedance anomalies, dipping soil layer contacts, and an undulating concrete base layer was imaged using 500- and 100-kHz transducers. The geometric features of the model are clearly visible in the images recorded with the 500-kHz transducers and less clear with the 100-kHz transducers. The lateral spatial resolution of the migrated images is shown to be much larger than one wavelength. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...] [article] p-Wave reflection imaging of submerged soil models using ultrasound [texte imprimé] / Joseph Coe, Auteur ; Scott J. Brandenberg, Auteur . - 2010 . - pp. 1358-1367. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 10 (Octobre 2010) . - pp. 1358-1367 Mots-clés : Soils  Ultrasonic  methods  Transfer  functions  Transducers  Imaging  techniques  Signal  processing  Submerging  Reflection  Compression  waves Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : An ultrasonic p-wave reflection imaging system is used to noninvasively image submerged soil models with embedded anomalies and complex geometric layer contacts. The ultrasonic transducers emit compressive waves into water that subsequently transmit into the underlying soil, and measurements of the reflections are used to construct the images. The properties of the transducers and data acquisition hardware and software are explained. Fast signal stacking is used to improve signal-to-noise ratio and provide clearer images. Transducer directivity is explained as a wave passage effect, and transfer functions are derived for square and circular transducers to quantify directivity. The transfer functions agree reasonably with measured amplitude data. The cause of errors in the imaged position of dipping reflectors is explained, and a Kirchhoff migration algorithm is implemented to correct these errors. A soil model consisting of embedded high- and low-impedance anomalies, dipping soil layer contacts, and an undulating concrete base layer was imaged using 500- and 100-kHz transducers. The geometric features of the model are clearly visible in the images recorded with the 500-kHz transducers and less clear with the 100-kHz transducers. The lateral spatial resolution of the migrated images is shown to be much larger than one wavelength. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...]

Weighted residual numerical differentiation algorithm applied to experimental bending moment data / Scott J. Brandenberg in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 6 (Juin 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 6 (Juin 2010) . - pp. 854-863 Titre : Weighted residual numerical differentiation algorithm applied to experimental bending moment data Type de document : texte imprimé Auteurs : Scott J. Brandenberg, Auteur ; Daniel W. Wilson, Auteur ; Mark M. Rashid, Auteur Année de publication : 2010 Article en page(s) : pp. 854-863 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Differential  equations  Bending  moments  Centrifuge  model  Soil  liquefaction  Pile  foundations Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A weighted-residual approach for differentiating one-dimensional discrete data is presented and applied to an experimental program in which distributions of bending moment were measured along a model pile foundation in a centrifuge test. The weighted-residual approach is validated by first differentiating a sinusoidal bending moment distribution, and errors in first and second derivatives associated with various ratios of wavelength to sampling interval are computed. A bending moment distribution from a finite-element simulation of a pile foundation is differentiated using the weighted-residual technique, by fitting cubic splines, and by polynomial regression, and second derivatives are compared with the recorded subgrade reaction distributions. The influence of adding noise to the sampled bending moment distribution prior to differentiation is explored and is found to be most influential when sampling intervals are small. Bending moment data recorded during the centrifuge experiment are double differentiated and uncertainty in strain gauge calibration factors and position are incorporated using a Monte Carlo simulation to assess potential errors in the computed second derivatives. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i6/p854_s1?isAuthorized=no [article] Weighted residual numerical differentiation algorithm applied to experimental bending moment data [texte imprimé] / Scott J. Brandenberg, Auteur ; Daniel W. Wilson, Auteur ; Mark M. Rashid, Auteur . - 2010 . - pp. 854-863. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 6 (Juin 2010) . - pp. 854-863 Mots-clés : Differential  equations  Bending  moments  Centrifuge  model  Soil  liquefaction  Pile  foundations Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A weighted-residual approach for differentiating one-dimensional discrete data is presented and applied to an experimental program in which distributions of bending moment were measured along a model pile foundation in a centrifuge test. The weighted-residual approach is validated by first differentiating a sinusoidal bending moment distribution, and errors in first and second derivatives associated with various ratios of wavelength to sampling interval are computed. A bending moment distribution from a finite-element simulation of a pile foundation is differentiated using the weighted-residual technique, by fitting cubic splines, and by polynomial regression, and second derivatives are compared with the recorded subgrade reaction distributions. The influence of adding noise to the sampled bending moment distribution prior to differentiation is explored and is found to be most influential when sampling intervals are small. Bending moment data recorded during the centrifuge experiment are double differentiated and uncertainty in strain gauge calibration factors and position are incorporated using a Monte Carlo simulation to assess potential errors in the computed second derivatives. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i6/p854_s1?isAuthorized=no