Matching Items (29)

134138-Thumbnail Image.png

Earthquake-Induced Soil Liquefaction

Description

This thesis was prepared by Tyler Maynard and Hayley Monroe, who are students at Arizona State University studying to complete their B.S.E.s in Civil Engineering and Construction Engineering, respectively. Both

This thesis was prepared by Tyler Maynard and Hayley Monroe, who are students at Arizona State University studying to complete their B.S.E.s in Civil Engineering and Construction Engineering, respectively. Both students are members of Barrett, the Honors College, at Arizona State University, and have prepared the following document for the purpose of completing their undergraduate honors thesis. The early sections of this document comprise a general, introductory overview of earthquakes and liquefaction as a phenomenon resulting from earthquakes. In the latter sections, this document analyzes the relationship between the furthest hypocentral distance to observed liquefaction and the earthquake magnitude published in 2006 by Wang, Wong, Dreger, and Manga. This research was conducted to gain a greater understanding of the factors influencing liquefaction and to compare the existing relationship between the maximum distance for liquefaction and earthquake magnitude to updated earthquake data compiled for the purpose of this report. As part of this research, 38 different earthquake events from the Geotechnical Extreme Events Reconnaissance (GEER) Association with liquefaction data were examined. Information regarding earthquake depth, distance to the furthest liquefaction event (epicentral and hypocentral), and earthquake magnitude (Mw) from recent earthquake events (1989 to 2016) was compared to the previously established relationship of liquefaction occurrence distance to moment magnitude. The purpose of this comparison was to determine if recent events still comply with the established relationship. From this comparison, it was determined that the established relationship still generally holds true for the large magnitude earthquakes (magnitude 7.5 or above) that were considered herein (with only 2.6% falling above the furthest expected liquefaction distance). However, this relationship may be too conservative for recent, low magnitude earthquake events; those events examined below magnitude 6.3 did not approach established range of furthest expected liquefaction distance. The overestimation of furthest hypocentral distance to liquefaction at low magnitudes suggest the empirical relationship may need to be adjusted to more accurately capture recent events, as reported by GEER.

Contributors

Agent

Created

Date Created
  • 2017-12

135385-Thumbnail Image.png

Large Scale Direct Shear Testing of Municipal Solid Waste

Description

This thesis describes the conduct and interpretation of large scale direct shear testing of municipal solid waste (MSW) which was recently conducted at Arizona State University under the guidance of

This thesis describes the conduct and interpretation of large scale direct shear testing of municipal solid waste (MSW) which was recently conducted at Arizona State University under the guidance of Dr. Edward Kavazanjian Jr. This research was performed to establish the shear strength parameters for MSW of a particular landfill in the eastern United States. As part of this research, the unit weight of the material of interest was recorded to help establish if the properties of the waste tested in this project were consistent with the properties of MSW reported in the technical literature.
The paper begins with an overview of scholarly articles on shear strength and unit weight of MSW. This overview summarizes trends found in other MSW investigations. The findings described in these articles served as a basis to determine if the direct shear test results in this investigation complied with typical values reported in other MSW investigations.
A majority of this thesis is dedicated to describing testing protocol, nuances of experimental execution, and test results of the direct shear tests. This culminates in an analysis of the shear strength parameters and consolidated unit weight exhibited by the MSW tested herein. Throughout the testing displacement range of 3.5 inches, none of the MSW specimens achieved a peak shear stress. Consequently, the test results were analyzed at displacements of 1.7 inches, 2.1 inches, and 2.4 inches during the tests to develop Mohr-Coulomb envelopes for each specified displacement. All three envelopes indicated that the cohesion of the material was effectively 0 psf). The interpreted angles of internal friction were of 30.6°, 33.7°, and 36.0° for the displacements of 1.7, 2.1, and 2.4 inches, respectively. These values correlate well with values from previous investigations, indicating that from a shear strength basis the waste tested in this project was typical of MSW from other landfills. Analysis of the consolidated unit weight of the MSW specimens also suggests the MSW was similar to in-situ MSW which was placed in a landfill with low levels of compaction and small amounts of cover soil.

Contributors

Created

Date Created
  • 2016-05

137640-Thumbnail Image.png

Understanding Current Foundation Practices for High Rise Buildings

Description

After describing the types of foundation systems employed for high rise buildings, this thesis discusses the process of foundation design for tall buildings as it is practiced today, including computer

After describing the types of foundation systems employed for high rise buildings, this thesis discusses the process of foundation design for tall buildings as it is practiced today, including computer programs used in designing the foundations of high rise buildings. This thesis then presents the geotechnical in-situ and laboratory tests used to establish the parameters required for input to design analyses for high rise building foundations. This thesis subsequently describes the Construction Quality Assurance practices used in the construction of the foundations of high rise buildings. This thesis next presents several case histories detailing the foundation practices employed in the design and construction of modern high rise buildings. Finally, this thesis provides some concluding thoughts regarding the development of the geotechnical practices when designing and constructing high rise buildings.

Contributors

Agent

Created

Date Created
  • 2013-05

135444-Thumbnail Image.png

Automated Multi-Stage Triaxial Testing of Loose and Dense Sands

Description

The goal of this project was to develop criteria to signify when a soil specimen is just on the verge of failure when tested in a consolidated-drained triaxial test. By

The goal of this project was to develop criteria to signify when a soil specimen is just on the verge of failure when tested in a consolidated-drained triaxial test. By identifying the imminent failure of the specimen, a multi-stage triaxial test can be automated, allowing for soil strength properties to be determined from a single specimen. The purpose of identification of imminent failure of the specimen is for purposes of development of automated multi-stage test operation of a single specimen for determination of soil properties. Currently, shear strength parameters for a soil could either be calculated from at least three separate triaxial tests or a multi-stage test where each stage would end based on the operator's judgement. By developing generalized criteria that would signify failure, and therefore the need to move on to the next stage of a multi-state test, a computer program could be used to automatically end one loading stage and begin the next. This automation would allow for a wider use of multi-stage tests, which are faster and therefore less expensive to run than three standard triaxial tests. Triaxial tests were performed on loose and dense sand specimens. During standard testing, the loose sand had a friction angle of 29.61o and the dense sand had a friction angle of 38.63o. Using a zero tangent modulus as the stage-end criteria, the loose sand had a friction angle of 27.69o and the dense sand had a friction angle of 37.03o. Using the maximum volumetric strain as the stage-end criteria, the loose sand had a friction angle of 25.16o. The multi-stage shear strength parameters were reasonable compared to the single-stage test parameters, if slightly conservative. This suggests that computer automation of multi-stage triaxial tests will produce results that can be used in analysis and design by geotechnical engineers. However, more research will be required to confirm this initial assumptions for a wider range of sand gradations as well as for other soil types and testing conditions.

Contributors

Created

Date Created
  • 2016-05

137618-Thumbnail Image.png

Bioreactor Alternative to Conventional Landfills

Description

Currently conventional Subtitle D landfills are the primary means of disposing of our waste in the United States. While this method of waste disposal aims at protecting the environment, it

Currently conventional Subtitle D landfills are the primary means of disposing of our waste in the United States. While this method of waste disposal aims at protecting the environment, it does so through the use of liners and caps that effectively freeze the breakdown of waste. Because this method can keep landfills active, and thus a potential groundwater threat for over a hundred years, I take an in depth look at the ability of bioreactor landfills to quickly stabilize waste. In the thesis I detail the current state of bioreactor landfill technologies, assessing the pros and cons of anaerobic and aerobic bioreactor technologies. Finally, with an industrial perspective, I conclude that moving on to bioreactor landfills as an alternative isn't as simple as it may first appear, and that it is a contextually specific solution that must be further refined before replacing current landfills.

Contributors

Agent

Created

Date Created
  • 2013-05

153640-Thumbnail Image.png

An instructional design and development research study with an interdisciplinary instructional design (IdID) team in geotechnical engineering

Description

The purpose of this instructional design and development study was to describe, evaluate and improve the instructional design process and the work of interdisciplinary design teams. A National Science Foundation

The purpose of this instructional design and development study was to describe, evaluate and improve the instructional design process and the work of interdisciplinary design teams. A National Science Foundation (NSF) funded, Transforming Undergraduate Education in Science (TUES) project was the foundation for this study. The project developed new curriculum materials to teach learning content in unsaturated soils in undergraduate geotechnical engineering classes, a subset of the civil engineering. The study describes the instructional design (ID) processes employed by the team members as they assess the need, develop the materials, disseminate the learning unit, and evaluate its effectiveness, along with the impact the instructional design process played in the success of the learning materials with regard to student achievement and faculty and student attitudes. Learning data were collected from undergraduate geotechnical engineering classes from eight partner universities across the country and Puerto Rico over three phases of implementation. Data were collected from students and faculty that included pretest/posttest scores and attitudinal survey questions. The findings indicated a significant growth in the learning with the students of the faculty who were provided all learning materials. The findings also indicated an overall faculty and student satisfaction with the instructional materials. Observational and anecdotal data were also collected in the form of team meeting notes, personal observations, interviews and design logs. Findings of these data indicated a preference with working on an interdisciplinary instructional design team. All these data assisted in the analysis of the ID process, providing a basis for descriptive and inferential data used to provide suggestions for improving the ID process and the work of interdisciplinary instructional design teams.

Contributors

Agent

Created

Date Created
  • 2015

152596-Thumbnail Image.png

Probabilistic based assessment of the influence of nonlinear soil behavior and stratification on the performance of laterally loaded drilled pier foundations

Description

This thesis presents a probabilistic evaluation of multiple laterally loaded drilled pier foundation design approaches using extensive data from a geotechnical investigation for a high voltage electric transmission line. A

This thesis presents a probabilistic evaluation of multiple laterally loaded drilled pier foundation design approaches using extensive data from a geotechnical investigation for a high voltage electric transmission line. A series of Monte Carlo simulations provide insight about the computed level of reliability considering site standard penetration test blow count value variability alone (i.e., assuming all other aspects of the design problem do not contribute error or bias). Evaluated methods include Eurocode 7 Geotechnical Design procedures, the Federal Highway Administration drilled shaft LRFD design method, the Electric Power Research Institute transmission foundation design procedure and a site specific variability based approach previously suggested by the author of this thesis and others. The analysis method is defined by three phases: a) Evaluate the spatial variability of an existing subsurface database. b) Derive theoretical foundation designs from the database in accordance with the various design methods identified. c) Conduct Monti Carlo Simulations to compute the reliability of the theoretical foundation designs. Over several decades, reliability-based foundation design (RBD) methods have been developed and implemented to varying degrees for buildings, bridges, electric systems and other structures. In recent years, an effort has been made by researchers, professional societies and other standard-developing organizations to publish design guidelines, manuals and standards concerning RBD for foundations. Most of these approaches rely on statistical methods for quantifying load and resistance probability distribution functions with defined reliability levels. However, each varies with regard to the influence of site-specific variability on resistance. An examination of the influence of site-specific variability is required to provide direction for incorporating the concept into practical RBD design methods. Recent surveys of transmission line engineers by the Electric Power Research Institute (EPRI) demonstrate RBD methods for the design of transmission line foundations have not been widely adopted. In the absence of a unifying design document with established reliability goals, transmission line foundations have historically performed very well, with relatively few failures. However, such a track record with no set reliability goals suggests, at least in some cases, a financial premium has likely been paid.

Contributors

Agent

Created

Date Created
  • 2014

156657-Thumbnail Image.png

Estimation of Pressuremeter Modulus From Shear Wave Velocity In the Sonoran Desert

Description

Laterally-loaded short rigid drilled shaft foundations are the primary foundation used within the electric power transmission line industry. Performance of these laterally loaded foundations is dependent on modulus of the

Laterally-loaded short rigid drilled shaft foundations are the primary foundation used within the electric power transmission line industry. Performance of these laterally loaded foundations is dependent on modulus of the subsurface, which is directly measured by the Pressuremeter (PMT). The PMT test provides the lateral shear modulus at intermediate strains, an equivalent elastic modulus for lateral loading, which mimics the reaction of transmission line foundations within the elastic range of motion. The PMT test, however, is expensive to conduct and rarely performed. Correlations of PMT to blow counts and other index properties have been developed but these correlations have high variability and may result in unconservative foundation design. Variability in correlations is due, in part, because difference of the direction of the applied load and strain level between the correlated properties and the PMT. The geophysical shear wave velocity (S-wave velocity) as measured through refraction microtremor (ReMi) methods can be used as a measure of the small strain, shear modulus in the lateral direction. In theory, the intermediate strain modulus of the PMT is proportional to the small strain modulus of S-wave velocity. A correlation between intermediate strain and low strain moduli is developed here, based on geophysical surveys conducted at fourteen previous PMT testing locations throughout the Sonoran Desert of central Arizona. Additionally, seasonal variability in S-wave velocity of unsaturated soils is explored and impacts are identified for the use of the PMT correlation in transmission line foundation design.

Contributors

Agent

Created

Date Created
  • 2018

155622-Thumbnail Image.png

Strain concentrations in polyethylene geomembranes adjacent to seams and scratches

Description

Laboratory testing was conducted to quantify strain concentrations adjacent to seams and scratches in high density polyethylene (HDPE) geomembranes. The tensile strain profile of remnants meeting the ASTM criteria for

Laboratory testing was conducted to quantify strain concentrations adjacent to seams and scratches in high density polyethylene (HDPE) geomembranes. The tensile strain profile of remnants meeting the ASTM criteria for wide-width tensile testing from samples of field seams recovered for construction quality assurance testing was evaluated using digital image correlation (DIC). Strains adjacent to scratches on laboratory prepared samples loaded in tension were also measured using DIC. The tensile strain in the zone adjacent to a seam and the tensile strain adjacent to a scratch were compared to the tensile strains calculated using theoretical strain concentration factors. The relationship between the maximum tensile strain adjacent to a seam and the global nominal strain in the sample was quantified for textured and smooth geomembranes of common thicknesses. Using statistical analysis of the data, bounds were developed for the allowable nominal tensile strain expected to induce maximum tensile strains adjacent to the seam less than or equal to the typical yield strain of HDPE geomembranes, at several confidence levels. Where nominal strain is the global or average strain applied to the sample and maximum strain is the largest tensile strain induced in the sample.

The reduction in the nominal yield strain due to a scratch in a HDPE geomembrane was also quantified. The yield strain was approximately the same as predicted using theoretical strain concentration factors. The difference in the average measured maximum strains adjacent to the seams of textured and smooth HDPE geomembranes was found to be statistically insignificant. However, maximum strains adjacent to extrusion welded seams were somewhat greater than adjacent to fusion welded seams for nominal strains on the order of 3% to 4%. The results of the testing program suggest that the nominal tensile strain should be limited to 4% around dual hot wedge seams and 3% around extrusion fillet seams to avoid maximum strains equal to 11%, a typical yield strain for HDPE geomembranes.

Contributors

Agent

Created

Date Created
  • 2017

156066-Thumbnail Image.png

Evaluation of Testing Methods for Suction-Volume Change of Natural Clay Soils

Description

Design and mitigation of infrastructure on expansive soils requires an understanding of unsaturated soil mechanics and consideration of two stress variables (net normal stress and matric suction). Although numerous

Design and mitigation of infrastructure on expansive soils requires an understanding of unsaturated soil mechanics and consideration of two stress variables (net normal stress and matric suction). Although numerous breakthroughs have allowed geotechnical engineers to study expansive soil response to varying suction-based stress scenarios (i.e. partial wetting), such studies are not practical on typical projects due to the difficulties and duration needed for equilibration associated with the necessary laboratory testing. The current practice encompasses saturated “conventional” soil mechanics testing, with the implementation of numerous empirical correlations and approximations to obtain an estimate of true field response. However, it has been observed that full wetting rarely occurs in the field, leading to an over-conservatism within a given design when partial wetting conditions are ignored. Many researchers have sought to improve ways of estimation of soil heave/shrinkage through intense studies of the suction-based response of reconstituted clay soils. However, the natural behavior of an undisturbed clay soil sample tends to differ significantly from a remolded sample of the same material.

In this study, laboratory techniques for the determination of soil suction were evaluated, a methodology for determination of the in-situ matric suction of a soil specimen was explored, and the mechanical response to changes in matric suction of natural clay specimens were measured. Suction-controlled laboratory oedometer devices were used to impose partial wetting conditions, similar to those experienced in a natural setting. The undisturbed natural soils tested in the study were obtained from Denver, CO and San Antonio, TX.

Key differences between the soil water characteristic curves of the undisturbed specimen test compared to the conventional reconstituted specimen test are highlighted. The Perko et al. (2000) and the PTI (2008) methods for estimating the relationship between volume and changes in matric suction (i.e. suction compression index) were evaluated by comparison to the directly measured values. Lastly, the directly measured partial wetting swell strain was compared to the fully saturated, one-dimensional, oedometer test (ASTM D4546) and the Surrogate Path Method (Singhal, 2010) to evaluate the estimation of partial wetting heave.

Contributors

Agent

Created

Date Created
  • 2017