Download or read book Development of Shear Wave Velocity Profiles in the Deep Sediments of the Mississippi Embayment Using Surface Wave and Spectral Ratio Methods written by Jonathan Pqul Bailey and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The deep soils of the Mississippi Embayment in the central United States will have a significant influence on earthquake ground motions generated by the New Madrid Seismic Zone. The seismic properties of these soils, which extend to depths of over 1000 meters in some areas, are poorly characterized at depths below 60 to 100 meters. This study presents shear wave velocity (Vs) profiles determined from Spectral-Analysis-of-Surface-Waves (SASW) measurements performed at eleven sites in Arkansas, Tennessee, and Missouri. These measurements were performed using the low-frequency field vibrator developed as part of the NSF Network for Earthquake Engineering Simulation (NEES) program. Shear wave velocity profiles were developed to depths of approximately 220 meters at eleven sites located throughout the Mississippi Embayment. In addition to the SASW measurements, ambient noise measurements of horizontal and vertical ground motions were performed to estimate the average Vs over the full profile depth using the H/V spectral ratio method. The Vs profiles derived from the SASW measurements compared well with Vs reference profiles that have been developed for the Mississippi Embayment and used in recent site response studies of the region. The observed variability of the profiles was found to be in general agreement with past assumptions used for the deep soil and correlated with changes in soil lithology. Relationships between the soil formations and Vs were consistent with past studies and provided information to greater depths. Lastly the H/V spectral ratio measurements were successfully applied at each of the eleven sites, but appeared to overestimate the average Vs.
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 Development of Deep Site Specific and Reference Shear Wave Velocity Profiles in the Canterbury Plains New Zealand written by Michael Ryan Deschenes and published by . This book was released on 2017 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deep (typically >1000 m) shear wave velocity profiles were developed across the Canterbury basin at nine strong motion stations using a combination of active and passive surface wave methods and horizontal to vertical spectral ratio measurements. A multi-mode, multi-method joint inversion process, which included Rayleigh and Love wave dispersion and horizontal to vertical spectral ratio data, was used to estimate the shear wave velocity profiles at each site. A-priori geologic information was utilized in defining preliminary constraints on the complex geologic layering of the Canterbury basin. At sites where interbedded layers were present, velocity reversals were considered in the inversion. Shear wave velocity profiles developed as part of this study were combined with the median profiles from 14 Christchurch sites detailed in a separate study, to develop a suite of region and soil specific reference shear wave velocity profiles for the Canterbury basin. Site specific and reference shear wave velocity profiles developed as part of this study can be used for back-analysis of earthquake ground motions, forward analysis of future ground motions, full 3D physics based simulations, or to refine 3D velocity models for the region. 1000 m) shear wave velocity profiles were developed across the Canterbury basin at nine strong motion stations using a combination of active and passive surface wave methods and horizontal to vertical spectral ratio measurements. A multi-mode, multi-method joint inversion process, which included Rayleigh and Love wave dispersion and horizontal to vertical spectral ratio data, was used to estimate the shear wave velocity profiles at each site. A-priori geologic information was utilized in defining preliminary constraints on the complex geologic layering of the Canterbury basin. At sites where interbedded layers were present, velocity reversals were considered in the inversion. Shear wave velocity profiles developed as part of this study were combined with the median profiles from 14 Christchurch sites detailed in a separate study, to develop a suite of region and soil specific reference shear wave velocity profiles for the Canterbury basin. Site specific and reference shear wave velocity profiles developed as part of this study can be used for back-analysis of earthquake ground motions, forward analysis of future ground motions, full 3D physics based simulations, or to refine 3D velocity models for the region.
Download or read book Shear Waves in Marine Sediments written by J.M Hovem and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 593 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shear waves and closely related interface waves (Rayleigh, Stoneley and Scholte) play an important role in many areas of engineering, geophysics and underwater acoustics. In some cases interest is focused on large-amplitude waves of low frequency such as those associ ated with earthquakes and nuclear explosions; in other cases low amplitude waves, which have often travelled great distances through the sediment, are of interest. Both low and high frequency shear and interface waves are often used for seafloor probing and sediment characterization. As a result of the wide spectrum of different interests, different disciplines have developed lines of research and a literature particularly suited to their own problems. For example water-column acousticians view the seafloor sediment as the lower boundary of their domain and are interested in shear and interface waves in the near bottom sediments mainly from the standpoint of how they influence absorption and reflection at this boundary. On the other hand, geophysicists seeking deep oil deposits are interested in the maximum penetration into the sediments and the tell-tale characteristics of the seismic waves that have encountered potential oil or gas bearing strata. In another area, geotechnical engineers use shear and interface waves to study soil properties necessary for the design and the siting of seafloor structures.
Download or read book A 2 D MASW Shear wave Velocity Profile Along a Test Segment of Interstate I 70 St Louis Missouri written by N. Anderson and published by . This book was released on 2004 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The University of Missouri-Rolla acquired multi-channel surface wave (Rayleigh wave) seismic data along a 6400 ft segment of Interstate I-70 in downtown St. Louis, Missouri. The acquired surface wave data set was processed [multi-channel analysis of surface waves (MASW)] and transformed into a 2-D MASW shear-wave velocity profile with a station-spacing of 40 ft. The interpreted depth to bedrock along the length of the 2-D profile varies between 20 ft and 44 ft. Geotechnical data provided by the Missouri Department of Transportation and presented herein indicates the interpreted 2-D MASW shear-wave velocity profile correlates well with available bedrock (borehole) and seismic cone penetrometer control, supporting the conclusion that the MASW technique can be used to generate reliable 2-D shear-wave velocity profiles.
Download or read book Vertical Shear wave Velocity Profiles Generated from Spectral Analysis of Surface Waves written by Dr. Neil Anderson and published by . This book was released on 2003 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface wave (Rayleigh wave) seismic data were acquired at six separate bridge sites in southeast Missouri. Each acquired surface wave data set was processed [spectral analysis of surface waves (SASW)] and transformed into a site-specific vertical shear-wave velocity profile (SASW shear-wave velocity profile). The SASW shear-wave velocity profiles generated for each bridge site were compared to other geotechnical data including seismic cone penetrometer shear-wave velocity profiles, cross-borehole shear-wave velocity profiles, and borehole lithology logs. The geotechnical data presented herein indicate the SASW shear-wave velocity profiles correlate well with subsurface lithology logs and available cross-borehole shear-wave velocity control. More specifically, clays, silts and sands exhibit relatively characteristic SASW shear-wave velocities, which increase incrementally with increasing depth of burial. The authors believe these correlations demonstrate that SASW shear-wave velocities are reliable.
Download or read book Shear wave Velocities in Parkway Basin Wainuiomata from Refraction Microtremor Surface Wave Dispersion written by A. E. Kaiser and published by . This book was released on 2006 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Earthquake Geotechnical Engineering Design written by Michele Maugeri and published by Springer Science & Business Media. This book was released on 2014-02-03 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pseudo-static analysis is still the most-used method to assess the stability of geotechnical systems that are exposed to earthquake forces. However, this method does not provide any information about the deformations and permanent displacements induced by seismic activity. Moreover, it is questionable to use this approach when geotechnical systems are affected by frequent and rare seismic events. Incidentally, the peak ground acceleration has increased from 0.2-0.3 g in the seventies to the current value of 0.6-0.8 g. Therefore, a shift from the pseudo-static approach to performance-based analysis is needed. Over the past five years considerable progress has been made in Earthquake Geotechnical Engineering Design (EGED). The most recent advances are presented in this book in 6 parts. The evaluation of the site amplification is covered in Part I of the book. In Part II the evaluation of the soil foundation stability against natural slope failure and liquefaction is treated. In the following 3 Parts of the book the EGED for different geotechnical systems is presented as follows: the design of levees and dams including natural slopes in Part III; the design of foundations and soil structure interaction analysis in Part IV; underground structures in Part V. Finally in Part VI, new topics like the design of reinforced earth retaining walls and landfills are covered.
Download or read book A New Procedure for Estimation of Shear Wave Velocity Profiles Using Multi Station Spectral Analysis of Surface Waves Regression Line Slope and Genetic Algorithm Methods written by Morteza Zarrabi and published by . This book was released on 2006 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismological Research Letters written by and published by . This book was released on 2006 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Acoustic and Related Properties of the Sea Floor Shear Wave Velocity Profiles and Gradients written by Edwin L. Hamilton and published by . This book was released on 1975 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of the velocity of shear waves at various depths in common watersaturated sediments were collected from published studies. Because measurements in marine sediments are rare, most of this information came from land geology and geophysics. This report considered the two end-member sediments types: sand and silt-clays, including turbidites which are alternating layers of silt-clay with thinner layers of silt and sand. The shear velocity measurements in sands were 29 selected, in situ values at depths to 12m. Data from laboratory and field studies indicate that shear wave velocity is proportional to the 1/3 to 1/6 power of pressure or depth in sands; that the 1/6 power is not reached until very high pressures are applied; and that for most sand bodies the exponent is between 3/10 and 1/4. Data from laboratory studies allow prediction of compressional wave (sound) as a function of depth in sands. The shear velocity measurements in silt-clays and turbidites used in this report include 47 measurements to depths of 650 m. Three linear equations were used to characterize the data. The shear velocity gradient in the upper 40m(4.65/sec) is 4-5 times greater than is the compressional wave (sound) velocity gradient in comparable sediments. At deeper depths, shear velocity and compressional velocity gradients are comparable. This report concludes with methods for prediction of shear wave velocity profiles and gradients in sea-floor sediments. This result will be of immediate use in a sophisticated model that determines sound energy losses when an acoustic wave interacts with the sea floor.
Download or read book Development and Implementation of an Underwater System for Interface Wave Measurements written by Matthew M. Hollrah and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Measuring shear wave velocity profiles has become integral to geotechnical site investigation both on land and offshore. Obtaining accurate near-surface profiles in soft marine sediments can be expensive and time consuming using conventional intrusive methods. This work includes the development and field testing of an underwater source capable of generating surface wave energy for the determination of shear wave velocity profiles with resolution in the top foot to depths up to 20 feet. A portable and remotely fired underwater impact source was developed. Dispersion curves generated using conventional surface wave methods and instrumentation for shallow testing on land were compared to those obtained using the source. Additionally, underwater measurements using both contacting and noncontacting receivers were performed. Underwater measurements showed that Scholte waves could be generated wavelength range of interest. Non-contacting interface wave measurements were compared to contacting measurements and show promising results with a need for further investigation.
Download or read book On the Development of Uncertainty consistent One dimensional Shear Wave Velocity Profiles from Inversion of Surface Wave Dispersion Data written by Joseph Philip Vantassel and published by . This book was released on 2021 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shear wave Velocity Database and Derivative Mapping for the Upper Mississippi Embayment written by David M. Vance and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Local Site Conditions on the Reliability of Fundamental Mode Surface Wave Inversion Methods written by Brent L. Rosenblad and published by . This book was released on 2009 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of reliable shear wave velocity (VS) profiles from surface wave velocity measurements requires compatibility between the measured and theoretical dispersion curves used in the inversion procedure. The most common approach in geotechnical applications is to use a fundamental-mode theoretical dispersion curve based on the assumption that the measured dispersion curve is representative of the fundamental mode of surface wave propagation. Analyses of low-frequency surface wave measurements presented in this paper show that this widespread assumption is invalid at low frequencies (long wavelengths) for some profile conditions. Results are presented from measurements performed at two deep soil sites in the central United States where surface wave analyses were performed using both the common fundamental-mode approach as well as an "effective-velocity" approach. At one site these two methods produced essentially the same estimate of the VS profile, while at the second site the estimated VS values at depth differed by more than 40 %. Using soil profile information for these sites and simulations of surface wave propagation, it is shown that the shallower depth to a higher-velocity formation at the second site created dominant higher-mode energy at wavelengths of 300-600 m, resulting in an overestimation of deep VS values.
Download or read book Reducing Uncertainties in the Velocities Determined by Inversion of Phase Velocity Dispersion Curves Using Synthetic Seismograms written by Seyed Mehrdad Hosseini and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Characterizing the near-surface shear-wave velocity structure using Rayleigh-wave phase velocity dispersion curves is widespread in the context of reservoir characterization, exploration seismology, earthquake engineering, and geotechnical engineering. This surface seismic approach provides a feasible and low-cost alternative to the borehole measurements. Phase velocity dispersion curves from Rayleigh surface waves are inverted to yield the vertical shear-wave velocity profile. A significant problem with the surface wave inversion is its intrinsic non-uniqueness, and although this problem is widely recognized, there have not been systematic efforts to develop approaches to reduce the pervasive uncertainty that affects the velocity profiles determined by the inversion. Non-uniqueness cannot be easily studied in a nonlinear inverse problem such as Rayleigh-wave inversion and the only way to understand its nature is by numerical investigation which can get computationally expensive and inevitably time consuming. Regarding the variety of the parameters affecting the surface wave inversion and possible non-uniqueness induced by them, a technique should be established which is not controlled by the non-uniqueness that is already affecting the surface wave inversion. An efficient and repeatable technique is proposed and tested to overcome the non-uniqueness problem; multiple inverted shear-wave velocity profiles are used in a wavenumber integration technique to generate synthetic time series resembling the geophone recordings. The similarity between synthetic and observed time series is used as an additional tool along with the similarity between the theoretical and experimental dispersion curves. The proposed method is proven to be effective through synthetic and real world examples. In these examples, the nature of the non-uniqueness is discussed and its existence is shown. Using the proposed technique, inverted velocity profiles are estimated and effectiveness of this technique is evaluated; in the synthetic example, final inverted velocity profile is compared with the initial target velocity model, and in the real world example, final inverted shear-wave velocity profile is compared with the velocity model from independent measurements in a nearby borehole. Real world example shows that it is possible to overcome the non-uniqueness and distinguish the representative velocity profile for the site that also matches well with the borehole measurements.
Download or read book Determination of Shallow Shear Wave Velocity Structure and Attenuation in the Mississippi Embayment from VSP and Refraction Data written by Jiandang Ge and published by . This book was released on 2005 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt:
