Download or read book Experimental and theoretical studies in support of implementing the spectral analysis of surface wave SASW method offshore written by Brent Lyndon Rosenblad and published by . This book was released on 2000 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theoretical investigation of the spectral analysis of surface waves SASW technique for application offshore written by Mahmoud Sedighi Manesh and published by . This book was released on 1991 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book In Situ Measurement of Stiffness Profiles in the Seafloor Using the Spectral analysis of surface waves SASW Method written by Barbara Aileen Luke and published by . This book was released on 1995 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analytical Study of the Spectral analysis of surface waves Method at Complex Geotechnical Sites written by Jeffrey D. Bertel and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Surface Wave Methods for Near Surface Site Characterization written by Sebastiano Foti and published by CRC Press. This book was released on 2014-08-21 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2001 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental study of applying the spectral analysis of surface waves method offshore written by Robert C. Gauer and published by . This book was released on 1990 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Inversion Method for Spectral Analysis of Surface Waves SASW written by Maria Catalina Orozco and published by . This book was released on 2003 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Experimental Investigation of Near field Effects on the SASW Dispersion Curve written by Sungmoon Hwang and published by . This book was released on 2014 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Analytical Studies of Surface Wave Propagation Along the Seafloor for Application to Spectral analysis of surface waves SASW Testing written by Byungsik Lee and published by . This book was released on 1996 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings written by and published by . This book was released on 1993 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Interpretation and Analysis Techniques for Spectral analysis of surface waves SASW Measurements written by Sung-Ho Joh and published by . This book was released on 1997 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 2000 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Surface Wave Methods for Deep Shear Wave Velocity Profiling Applied in the Upper Mississippi Embayment written by Jianhua Li and published by . This book was released on 2008 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface wave methods have become an important tool for non-intrusively and inexpensively determining shear wave velocity (V [subscript-s]) profiles for many geotechnical earthquake engineering applications. The primary objectives of this study are to (1) compare active-source and passive (ambient vibration) surface wave methods for developing V [subscript-s] profiles to depths of 200 to 300 m at deep soil sites, and (2) identify the primary factors affecting the reliability and consistency of surface wave methods. This comparative study became possible with the advent of a unique low- frequency field vibrator developed as part of the National Science Foundation's (NSF) Network for Earthquake Engineering Simulation (NEES) program. This vibrator is able to actively excite surface wave energy down to frequencies of less than 1 Hz. Four surface wave methods (two active-source methods and two passive-source methods) were applied in this study, namely: (1) the Spectral-Analysis-of-Surface-Waves (SASW) method, (2) the active-source frequency- wavenumber ([function]-k) method, (3) the passive-source frequency-wavenumber ([function]-k) method and (4) the refraction microtremor (ReMi) method. The focus of this study is on two critical aspects of surface wave methods: (1) development of a reliable surface wave dispersion curve from field measurements, and (2) compatibility between the experimental dispersion curve and the theoretical model used in the inversion procedure to develop the final V [subscript-s] profile. Measurements were performed at eleven sites distributed over a distance of about 180 km in the upper Mississippi Embayment in the central United States, where soil deposits are hundreds of meters deep. Limitations associated with each of the four methods were identified in this study. With respect to the SASW method it was found that potential phase unwrapping problems could cause an erroneous estimate of the dispersion curve. These errors were found to be associated with an abrupt mode transition caused by a strong velocity contrast at a shallow depth. With respect to the active-source [function]-k approach, it was demonstrated that near-field effects caused by a short near- source offset produced an underprediction of the surface wave dispersion curve at long wavelengths. Recommendations for acceptable source offset distances were developed based on the results from this study. The performance of the passive approaches (passive [function]-k method and ReMi method) was shown to be strongly dependent on the local ambient wavefield characteristics. Results from a study of the ambient wavefield characteristics at the 11 sites showed high ambient vibration levels at all sites in the frequency range of 1 to 4 Hz. Passive measurements using a circular array provided good comparisons with the active-source methods out to wavelengths of 500 m (2.5 times the array aperture) in most cases. Poor performance at one site was shown to be due to a multi-source wavefield at low frequencies. An improved comparison at this site was achieved by applying high-resolution processing methods. The ReMi method was found to provide good results down to frequencies of 3 to 4 Hz (wavelengths of 100 to 150 m) but very poor performance at lower frequencies (
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 1102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surface Wave Methods for Near Surface Site Characterization written by Claudio Strobbia and published by CRC Press. This book was released on 2017-03-29 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Automation of Spectral Analysis of Surface Waves Method written by S. Nazarian and published by . This book was released on 1994 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: With minimal simplifying assumptions and approximations, an automated version of the spectral analysis of surface waves (SASW) method has been developed to determine in situ shear wave velocity profiles of soil deposits. Testing time for each site, including collection of data, construction and inversion of dispersion curve, should not be more than thirty minutes. To accelerate field testing, a multi-sensor geophone array and a PC-based data-acquisition, signal-analysis package have been developed. The two greatest challenges have been the development of a fully-automated procedure to construct the dispersion curve from field data and a fast yet, theoretically-sound, inversion process to determine the shear wave velocity profile from a given dispersion curve. In this paper, the major theoretical and practical aspects of these two steps are described and discussed with examples.
