The frequency-dependent properties of Rayleigh-type surface waves can be utilized for imaging and characterizing the shallow subsurface. Most surface-wave analysis relies on the accurate calculation of phase velocities for the horizontally traveling fundamental-mode Rayleigh wave acquired by stepping out a pair of receivers at intervals based on calculated ground roll wavelengths. Interference by coherent source-generated noise inhibits the reliability of shear-wave velocities determined through inversion of the whole wave field. Among these nonplanar, nonfundamental-mode Rayleigh waves (noise) are body waves, scattered and nonsource-generated surface waves, and higher-mode surface waves. The degree to which each of these types of noise contaminates the dispersion curve and, ultimately, the inverted shear-wave velocity profile is dependent on frequency as well as distance from the source. Multichannel recording permits effective identification and isolation of noise according to distinctive traceto-trace coherency in arrival time and amplitude. An added advantage is the speed and redundancy of the measurement process. Decomposition of a multichannel record into a time variable-frequency format, similar to an uncorrelated Vibroseis record, permits analysis and display of each frequency component in a unique and continuous format. Coherent noise contamination can then be examined and its effects appraised in both frequency and offset space. Separation of frequency components permits real-time maximization of the S/N ratio during acquisition and subsequent processing steps. Linear separation of each ground roll frequency component allows calculation of phase velocities by simply measuring the linear slope of each frequency component. Breaks in coherent surface-wave arrivals, observable on the decomposed record, can be compensated for during acquisition and processing. Multichannel recording permits single-measurement surveying of a broad depth range, high levels of redundancy with a single field configuration, and the ability to adjust the offset, effectively reducing random or nonlinear noise introduced during recording. A multichannel shot gather decomposed into a sweptfrequency record allows the fast generation of an accurate dispersion curve. The accuracy of dispersion curves determined using this method is proven through field comparisons of the inverted shear-wave velocity (vs) profile with a downholevs profile.

/pdf/multichannel-analysis-of-surface-waves-yi4tcsl0li.pdf

Multichannel analysis of surface waves

1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

The shear‐wave (S-wave) velocity of near‐surface materials (soil, rocks, pavement) and its effect on seismic‐wave propagation are of fundamental interest in many groundwater, engineering, and environmental studies. Rayleigh‐wave phase velocity of a layered‐earth model is a function of frequency and four groups of earth properties: P-wave velocity, S-wave velocity, density, and thickness of layers. Analysis of the Jacobian matrix provides a measure of dispersion‐curve sensitivity to earth properties. S-wave velocities are the dominant influence on a dispersion curve in a high‐frequency range (>5 Hz) followed by layer thickness. An iterative solution technique to the weighted equation proved very effective in the high‐frequency range when using the Levenberg‐Marquardt and singular‐value decomposition techniques. Convergence of the weighted solution is guaranteed through selection of the damping factor using the Levenberg‐Marquardt method. Synthetic examples demonstrated calculation efficiency and stability ...

/pdf/estimation-of-near-surface-shear-wave-velocity-by-inversion-29l31bs7zn.pdf

Estimation of near‐surface shear‐wave velocity by inversion of Rayleigh waves

PART 1 DEALS WITH THE DYNAMIC ASPECTS OF THE SUBJECT: MATHEMATICAL ANALYSIS OF SYSTEMS SUBJECTED TO INDEPENDENT VIBRATIONS BY MEANS OF MATHEMATICAL MODELS. THE ANALYTICAL SYSTEMS USED ARE NON-LINEAR SYSTEMS, HYDRODYNAMICS AND NUMERICAL METHODS. PART 2 EXAMINES SEISMIC MOVEMENTS, THE DYNAMIC BEHAVIOUR OF STRUCTURES AND THE BASIC CONCEPTS OF THE SEISMIC DESIGN OF STRUCTURES.

Fundamentals of earthquake engineering

Coagulation/flocculation in dewatering of sludge: A review.

Results from laboratory investigations for evaluation and enhancement of the dewatering performance of fine silt slurry are presented. These experiments were conducted with and without polymer conditioning of the slurry. One type of soil and five types of geotextile were used. The optimal dewatering conditions were investigated using one woven geotextile. An innovative methodology is proposed for determining optimal dewatering considerations using a combination of simple bench-scale tests (jar sedimentation test, jar test, and pressure filtration test). The current state of practice utilises a trial-and-error approach heavily dependent on operator judgement, and ignores the role of the geotextile and the simulation of field mixing conditions. The proposed methodology provides a rational method to determine the optimal dewatering conditions in terms of dewatering time and amount of piping under anticipated field conditions. This novel approach guides the selection and evaluation of candidate polymers, whic...

Effect of polymer conditioning on dewatering characteristics of fine sediment slurry using geotextiles

Frequency Distribution of Void Ratio of Granular Materials Determined by an Image Analyzer

To address the dropoff of women in engineering at the graduate level, the Women in Science and Engineering (WiSE) program at Syracuse University collaborated with the Graduate School and Colleges of Engineering and Computer Science and Arts and Sciences to create a program for women graduate students in science and engineering. This paper provides an overview of available data on women in engineering and of the barriers they encounter. It then discusses the authors’ experiences with the WiSE Future Professionals Program (WiSE-FPP). Assessment data showed that WiSE-FPP provided a strong peer support network for program participants and gave the women an opportunity to engage with other women in STEM going through the same experiences. The peer mentoring offered by the program helped address barriers of isolation and the lack of successful women role models at the graduate level.

https://ascelibrary.org/doi/pdf/10.1061/%28ASCE%29LM.1943-5630.0000081

"If these women can do it, i can do it, too": Building women engineering leaders through graduate peer mentoring

Six of the most commonly used methods for evaluating the pore-size distribution of geotextiles in the United States and Europe are reviewed: dry sieving, hydrodynamic sieving, wetsieving, bubblepoint method,mercury intrusionporosime- try,andimageanalysis.Inthisstudy,thesemethodswereusedtoevaluatepore-sizedis- tribution characteristics of over 580 specimens from 28 different geotextiles. The re- sults are presented in this paper. In general, the sieving and image analysis techniques required greater amounts of time to perform than the bubble point and mercury intru- sion porosimetry tests. The bubble point and mercury intrusion porosimetry tests re- quired extensive preliminary studyof testingparameters andtest equipment, however, theywere fairlysimple andrapidto perform. Typical resultsare givenfor eachmethod and confirm that there are fundamental differences between the methods. Before any test method is used and applied to the design of geotextiles as filters, it is imperative that the mechanisms of the test and the factors which may influence the test results are understood.

Geotextile Characterization and Pore-Size Distribution: Part II. A Review of Test Methods and Results

For the design of a geotextile as a filter, reliable information about the pore-size distribution of the geotextile is needed. The bubble point method is one technique that is able to provide this information for a geotextile. The bubble point method is a simple and rapid technique for evaluating pore-size distributions of virgin, clogged, and stretched geotextiles. In addition, the bubble point equipment is also capable of providing information as to the degree of clogging within a geotextile and the permeability of a geotextile. The geotextile pore-size distribution results obtained by the bubble point method showed good repeatability. However, the bubble point method was only able to distinguish between geotextiles that had significantly different cross sections. Pore-size distribution results for geotextiles with similar cross sections, but of increasing thickness, were very similar. The dry sieving (ASTM D 4751), hydrodynamic sieving (CAN/CGSB-148.1-10), AND WET SIEVING (sw-640550-83) METHODS ARE GENERALLY only useful for evaluating the larger pore openings (O95, O90) of the geotextiles. In addition, the methods are time consuming. The mercury intrusion porosimetry method (ASTM D 4404) was also performed; however, there was little difference in pore-size distribution results for any of the 28 different geotextiles tested (Smith 1993). There are also environmental concerns with using mercury. The bubble point method showed potential for characterizing the pore-size distribution of geotextiles.

Shobha K Bhatia

Papers

Effect of polymer conditioning on dewatering characteristics of fine sediment slurry using geotextiles

Frequency Distribution of Void Ratio of Granular Materials Determined by an Image Analyzer

"If these women can do it, i can do it, too": Building women engineering leaders through graduate peer mentoring

Geotextile Characterization and Pore-Size Distribution: Part II. A Review of Test Methods and Results

Application of the Bubble Point Method to the Characterization of the Pore-Size Distribution of Geotextiles