Full Waveform Reflectivity for Inversion of Surface Wave Dispersion in Shallow Site Investigations

O’Neill, Adam

doi:10.4133/1.2923302

Cited by 44 publications

(49 citation statements)

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“…The halfspace V s was, however underestimated between 1.5 and 5.7m depth and the inverted V s appears to 'smooth' over the interlayer boundary. This 'smoothing' and underestimation has been observed previously by O'Neill (2004) and by Safani et al (2005) for a similar two layer model. In this case the smoothing is probably a result of the large velocity contrast between layers.…”

supporting

confidence: 53%

Assessment of an MASW Approach Incorporating Discrete Particle Modeling

Donohue

Long

2008

JEEG

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A Discrete Particle Scheme (DPS) consisting of interacting circular particles is utilized to examine a popular Multichannel Analysis of Surface Waves (MASW) approach. Synthetic earth models of various complexity are generated using the DPS and analyzed by selected MASW dispersion and inversion techniques. For simple two layer and multilayer models where velocity increases with depth, inversion using the dominant fundamental mode results in MASW profiles of shear wave velocity [Formula: see text] that closely match the true synthetic [Formula: see text] profiles. Inversion using the default parameters produces gradational increases in velocity, rather than true discontinuities. When tested on a multilayer model containing a low velocity layer (LVL), inversion using a fundamental mode assumption results in a moderate increase in error. MASW field tests at a highly uniform site in Norway (Onsøy) and a site with distinctive layer boundaries in Ireland (Ballinasloe) result in highly repeatable profiles of [Formula: see text]. Resolution of dispersion curves at low frequencies [Formula: see text] is a problem at the Ballinasloe test site, which limits the depth of penetration of the technique. MASW inversion results compare excellently with downhole seismic cone tests at the Onsøy test site and reasonably with a seismic refraction survey at the Ballinasloe site.

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confidence: 53%

Assessment of an MASW Approach Incorporating Discrete Particle Modeling

Donohue

Long

2008

JEEG

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“…The resolution of MASW method is considered usually as a rule of thumb (Bodet et al 2005, Richart et al 1970, O'Neill 2003, Shtivelman 1999). Many conclusions are based on experimental results.…”

Section: Resolution Of Masw Methodsmentioning

confidence: 99%

Combination of HVSR and MASW Methods to Obtain Shear Wave Velocity Model of Subsurface in Israel

Gorstein

Ezersky

2015

IJGE

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Estimating possible site effect is an integral part of evaluation of the seismic hazard and reduction of earthquake damages. In regions with low or moderate seismicity as in Israel, the site response should be determined by analytical tools. These computations require knowledge of the subsurface geological structure in terms of shear-wave velocity (Vs) profile down to seismic bedrock. Conventionally, this problem is resolved by joint implementation of Horizontal-to-Vertical Spectral Ratios (HVSR or Nakamura's) technique, which is based on ambient noise measurements and seismic methods such as S-wave refraction or Multichannel Analysis of Surface Waves (MASW) method. The first one does not allow deep penetration of seismic waves because of its weak source. The MASW method using 4.5 Hz geophones is restricted in penetration depth of surface waves because of frequency (wavelength) limitations. In this study, we have applied 2.5 Hz geophones and special data processing to provide constructing Vs section to a depth of 100 m and deeper. In combination with HVSR measurements, MASW enables constructing reliable subsurface model, which could be integrated into the seismic hazard assessment. Testing of this combined methodology was carried out at a number of sites with differing geological structures in Israel.

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“…They concluded that the observed discontinuities were created by mode jumping between successively higher modes. This phenomenon was later emphasized by other researchers too ͑Foti et O'Neill, 2003;Zhang and Lu, 2003͒, but no studies have focused on the explanation of this behavior. Furthermore, in all these studies, the velocity of the bottom half-space was always set to be the highest velocity of the system in order to avoid tracing dispersion curves in the complex wave number domain.…”

Section: Background On Surface Wave Testing Of Pavementsmentioning

confidence: 99%

“…However, the potential of evaluating deeper embedded layers in a nondestructive manner has always been one of the main motivations for surface wave testing of pavements. It is mainly the inclusion of higher modes that has been assumed to be the main source of the experienced difficulties ͑Aouad, 1993; Foinquinos et al, 1995;Roesset et al, 1990͒. To resolve multiple modes of propagation, multichannel measurements and two-dimensional wave field transformation techniques have been introduced in near surface site characterization ͑Gabriels et Foti, 2000;O'Neill, 2003;Beaty and Smith, 2003͒. These methods require more data to be collected in the field but are capable of resolving different modes of propagation in the typical soil site frequency range of 5 to 80 Hz.…”

Section: Background On Surface Wave Testing Of Pavementsmentioning

confidence: 99%

“…The MASW transformation technique is described in Paper I of this thesis. Multichannel measurements and 2-D wavefield transformation techniques are now widely utilized in surface wave soil site applications (Zywicki, 1999;Foti, 2000;Beaty et al, 2002;O'Neill, 2003;Moro et al, 2003; The MASW method has so far been applied to geoenvironmental projects to map bedrock surface and find fracture zones where contamination can be spread with ground water and (Xia et al, 2000a), locate buried objects under the ground surface (Park et al, 1998a;1999a), map V S in water-bottom sediments with underwater MASW (Park et al, 2000b), perform joint analysis of both surface waves and refracted body waves (Ivanov et al, 2000a;2000b). In this thesis the MASW transformation technique is utilized in surface wave testing of pavements.…”

Section: πmentioning

confidence: 99%

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Surface wave testing of pavements.

Rydén

2009

The Journal of the Acoustical Society of America

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Pavements are constructed using several layers of materials, and their durability depends on the quality of all of these strata. It is, therefore, valuable to be able to determine the properties of the layers nondestructively. A method is presented for evaluating the thickness and stiffness of multilayered pavement structures from guided waves measured at the surface. In this type of layered structure, the interaction of leaky Lamb waves in the embedded layers generates surface waves corresponding only to certain portions of the guided wave dispersion curves and branches measurable at the pavement surface. To resolve the different mode branches, the wavefield is measured at the surface by using a light hammer as the source and an accelerometer as receiver, generating a synthetic receiver array. The recorded data are transformed to a phase velocity spectrum, which is then inverted to give the layer properties using a global inversion algorithm. The theoretical background along with experimental results of the application to nondestructive testing of pavements will be presented. Ongoing research on noncontact air-coupled measurements is also demonstrated. This opens up the possibility for faster on-the-fly surface wave testing of pavement layers, since surface contact is no longer required.

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Full Waveform Reflectivity for Inversion of Surface Wave Dispersion in Shallow Site Investigations

Cited by 44 publications

References 0 publications

Assessment of an MASW Approach Incorporating Discrete Particle Modeling

Assessment of an MASW Approach Incorporating Discrete Particle Modeling

Combination of HVSR and MASW Methods to Obtain Shear Wave Velocity Model of Subsurface in Israel

Surface wave testing of pavements.

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