Experimental and theoretical studies in support of implementing the spectral-analysis-of-surface-wave (SASW) method offshore PDF Download

Author: Brent Lyndon Rosenblad
Publisher:
ISBN:
Category : Seismic waves
Languages : en
Pages : 596

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Author: Barbara Aileen Luke
Publisher:
ISBN:
Category : Hydraulic models
Languages : en
Pages : 424

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Author: Mahmoud Sedighi Manesh
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 372

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Author: Sebastiano Foti
Publisher: CRC Press
ISBN: 1482266822
Category : Science
Languages : en
Pages : 482

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Develop a Greater Understanding of How and Why Surface Wave Testing WorksUsing examples and case studies directly drawn from the authors' experience, Surface Wave Methods for Near-Surface Site Characterization addresses both the experimental and theoretical aspects of surface wave propagation in both forward and inverse modeling. This book accents

Author: Jeffrey D. Bertel
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :

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The Spectral-Analysis-of-Surface-Waves (SASW) method is an accepted means of measuring shear wave velocity (VS). In some settings, SASW measurements have produced results that were inconsistent with results from other methods of measurement. The effectiveness of the SASW methodology at complex geotechnical sites was investigated to identify site conditions where the SASW approach may produce erroneous results. Analytical simulations of surface wave measurements were performed. A traditional SASW methodology (global analysis), and a more rigorous approach (array analysis) were used to generate experimental dispersion curves. The effectiveness of these approaches was evaluated by comparing the experimental results to the true dispersion curve. The global analysis yielded dispersion curves that tend to underestimate surface wave velocities at long wavelengths. The array approach worked well for both simple, gradually increasing VS profiles as well as for some complex profiles with large VS contrasts. In some cases both the global and array analysis produce an experimental dispersion curve that is not consistent with the theoretical dispersion curve, especially for soft-over-stiff profiles, a common profile encountered in the field. These results have implications for earthquake site response analysis.

Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 810

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Author: Robert C. Gauer
Publisher:
ISBN:
Category : Marine sediments
Languages : en
Pages : 450

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Author: Maria Catalina Orozco
Publisher:
ISBN:
Category : Rayleigh waves
Languages : en
Pages : 574

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This research focuses on estimating the shear wave velocity (Vs) profile based on the dispersion curve obtained from SASW field test data (i.e., inversion of SASW data). It is common for the person performing the inversion to assume the prior information required to constrain the problem based on his/her own judgment. Additionally, the Vs profile is usually shown as unique without giving a range of possible solutions. For these reasons, this work focuses on: (i) studying the non-uniqueness of the solution to the inverse problem; (ii) implementing an inversion procedure that presents the estimated model parameters in a way that reflects their uncertainties; and (iii) evaluating tools that help choose the appropriate prior information. One global and one local search procedures were chosen to accomplish these purposes: a pure Monte Carlo method and the maximum likelihood method, respectively. The pure Monte Carlo method was chosen to study the non-uniqueness by looking at the range of acceptable solutions (i.e., Vs profiles) obtained with as few constraints as possible. The maximum likelihood method was chosen because it is a statistical approach, which enables us to estimate the uncertainties of the resulting model parameters and to apply tools such as the Bayesian criterion to help select the prior information objectively. The above inversion methods were implemented for synthetic data, which was produced with the same forward algorithm used during inversion. This implies that all uncertainties were caused by the nature of the SASW inversion problem (i.e., there were no uncertainties added by experimental errors in data collection, analysis of the data to create the dispersion curve, layered model to represent a real 3-D soil stratification, or wave propagation theory). At the end of the research, the maximum likelihood method of inversion and the tools for the selection of prior information were successfully used with real experimental data obtained in Memphis, Tennessee.

Author: Sungmoon Hwang
Publisher:
ISBN:
Category :
Languages : en
Pages : 266

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When any method of surface wave testing that involves Rayleigh waves is performed, one important assumption is that plane Rayleigh waves are being measured. In the forward modeling or inversion procedure that is used to analyze the field dispersion curve to determine the field V[subscript s] profile, the analysis is based on the wave field consisting of plane Rayleigh waves. Therefore, field dispersion curves that contain near-field data could adversely distort the field V[subscript s] profile. To minimize the influence of near-field effects, several criteria have been recommended in the past. However, most of the criteria were based on empirical equations that implicitly assumed zones of influence, or numerical simulations. There is a lack of experimental investigation, particularly full-scale field investigations. Even, the numerical solutions have been based on simple soil profiles without significant velocity contrasts between soil layers and/or varying thicknesses of soil layers which can significantly influence near-field effects. Data from full-scale field test using the Spectral-Analysis-of-Surface-Waves (SASW) method was used in this thesis research. SASW tests performed at two stages in the construction of a deep, 90-ft thick backfill were studied. The V[subscript s] profiles were normally dispersive, with a substantial increase in the velocity of the layer beneath the backfill. The study shows the adverse distortions that can occur in the field dispersion curve from near-field effects when the spacing of the receiver pair is: (1) above the zone of rapidly increasing V[subscript s] near the surface and (2) less than the depth to the stiffer layer in deeper measurements. Other factors that affect the results are discussed and recommendations are presented to minimize the introduction of near-field effects, at least in these relatively simple V[subscript s] profiles.

Author: Byungsik Lee
Publisher:
ISBN:
Category : Surface waves (Oceanography)
Languages : en
Pages : 333

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