Site Characterization in Shelby County, Tennessee Using Advanced Surface Wave Methods

The focus of the current study was to develop improved experimental and analytical methods to increase the applicability and accuracy of seismic surface wave testing for use in geotechnical site characterization. The recent research completed by Zywicki (1999) on the use of array-based techniques for use in active and passive surface wave testing was refined and expanded resulting in the development of the current surface wave testing procedures. The current developments focused on improving the procedures typically used in traditional engineering surface wave studies by implementing array-based testing and analysis procedures and improved signal processing techniques. An experimental testing program was conducted to evaluate the developed procedures and to provide near-surface shear wave velocity (VS) data for the Memphis, Tennessee metropolitan region. This testing program consisted of 11 sites in Mid-America, ten within the Memphis, TN metropolitan area and one site in Northwest Arkansas. The testing program allowed for the comparison with previous data obtained using other in situ techniques, and with traditional surface wave data in order to validate the accuracy of the current methods and to highlight the improved capabilities over traditional surface wave methods. Additionally, active and passive procedures were combined in an effort to improve the range and capabilities of the individual methods allowing for more complete site characterization.National Science Foundation EEC-9701785published or submitted for publicatio

Multi-Scale Behavior at Geomaterial Interfaces

The design of interface elements in geotechnical engineering traditionally involves empiricism and lacks a solid fundamental underpinning based on the controlling mechanisms. These design shortcomings exist due to deficiencies in the fundamental understanding of geotechnical interface behaviors and the lack of test methods and devices available to directly measure interface properties in situ. The current work strives to improve the state of geotechnical knowledge and design with regard to interface behavior through fundamental laboratory studies and the development and use of a new in situ testing device. The current investigations are focused across a range of scales from micromechanical interactions to full scale field implementation. A series of laboratory investigations at the micromechanical level have been performed, specifically aimed at investigating the mechanisms controlling granular interactions against conventional and textured friction sleeves, and hook and loop type interactions present within textured geomembrane - geotextile systems. Additionally, a new in situ testing device has been designed and developed, the Multi Piezo Friction Attachment (MPFA), to allow for the characterization of geotechnical interface properties in situ within the context of an effective stress framework. The MPFA simultaneously provides four independent measures of interface friction (fPh.D.Committee Chair: Dr. J. David Frost; Committee Member: Dr. Carolyn D. Ruppel; Committee Member: Dr. Glenn J. Rix; Committee Member: Dr. Paul W. Mayne; Committee Member: Dr. Susan E. Burn

Site characterization in Shelby County, Tennessee using advanced surface wave methods

M.S.Glenn J. Ri

Interface Response-Based Soil Classification Framework

Current soil classification systems based on cone penetration testing (CPT) utilize a combination of the tip resistance (qt), pore pressure (u2), and friction sleeve (fs) measurements as inputs. While the qt measurements are typically normalized by the overburden stress, the fs measurements are often normalized by the net tip resistance, leading to the use of parameters that are dependent on each other. This paper presents the development of a soil classification framework that utilizes a normalized multi-friction parameter (MFP) and the CPT normalized tip resistance. The MFP parameter is obtained from measurements with textured friction sleeves from soundings with multi-sleeve attachments. The use of textured friction sleeves allows for fundamental differences in soil–structure interface behavior and particle sizes to be captured due to the significant degree of shearing induced within the soil. This classification framework was developed with results from over 30 soundings at six different sites. The analysis of samples taken from the field indicates that the proposed framework provides a classification that better agrees with the grain-size distribution for residuum, calcareous and intermediate soils, as compared to existing CPT-based systems. The potential development of a simplified probe with just one additional friction sleeve sensor can provide appropriate classification results and would facilitate adoption for use in practice.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author