Matching Items (8)
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- All Subjects: Geotechnical Engineering
- All Subjects: Soil permeability
- Creators: Kavazanjian, Edward
- Resource Type: Text
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 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.
ContributorsHeim, Zackary (Author) / Houston, Sandra (Thesis advisor) / Witczak, Matthew (Committee member) / Kavazanjian, Edward (Committee member) / Zapata, Claudia (Committee member) / Arizona State University (Publisher)
Created2014
Description
In geotechnical engineering, measuring the unsaturated hydraulic conductivity of fine grained soils can be time consuming and tedious. The various applications that require knowledge of the unsaturated hydraulic conductivity function are great, and in geotechnical engineering, they range from modeling seepage through landfill covers to determining infiltration of water under a building slab. The unsaturated hydraulic conductivity function can be measured using various direct and indirect techniques. The instantaneous profile method has been found to be the most promising unsteady state method for measuring the unsaturated hydraulic conductivity function for fine grained soils over a wide range of suction values. The instantaneous profile method can be modified by using different techniques to measure suction and water content and also through the way water is introduced or removed from the soil profile. In this study, the instantaneous profile method was modified by creating duplicate soil samples compacted into cylindrical tubes at two different water contents. The techniques used in the duplicate method to measure the water content and matric suction included volumetric moisture probes, manual water content measurements, and filter paper tests. The experimental testing conducted in this study provided insight into determining the unsaturated hydraulic conductivity using the instantaneous profile method for a sandy clay soil and recommendations are provided for further evaluation. Overall, this study has demonstrated that the presence of cracks has no significant impact on the hydraulic behavior of soil in high suction ranges. The results of this study do not examine the behavior of cracked soil unsaturated hydraulic conductivity at low suction and at moisture contents near saturation.
ContributorsJacquemin, Sean Christopher (Author) / Zapata, Claudia (Thesis advisor) / Houston, Sandra (Committee member) / Kavazanjian, Edward (Committee member) / Arizona State University (Publisher)
Created2011
Description
As a prelude to a study on the post-liquefaction properties and structure of soil, an investigation of ground freezing as an undisturbed sampling technique was conducted to investigate the ability of this sampling technique to preserve soil structure and properties. Freezing the ground is widely regarded as an appropriate technique to recover undisturbed samples of saturated cohesionless soil for laboratory testing, despite the fact that water increases in volume when frozen. The explanation generally given for the preservation of soil structure using the freezing technique was that, as long as the freezing front advanced uni-directionally, the expanding pore water is expelled ahead of the freezing front as the front advances. However, a literature review on the transition of water to ice shows that the volume of ice expands approximately nine percent after freezing, bringing into question the hypothesized mechanism and the ability of a frozen and then thawed specimen to retain the properties and structure of the soil in situ. Bench-top models were created by pluviation of sand. The soil in the model was then saturated and subsequently frozen. Freezing was accomplished using a pan filled with alcohol and dry ice placed on the surface of the sand layer to induce a unidirectional freezing front in the sample container. Coring was used to recover frozen samples from model containers. Recovered cores were then placed in a triaxial cell, thawed, and subjected to consolidated undrained loading. The stress-strain-strength behavior of the thawed cores was compared to the behavior of specimens created in a split mold by pluviation and then saturated and sheared without freezing and thawing. The laboratory testing provide insight to the impact of freezing and thawing on the properties of cohesionless soil.
ContributorsKatapa, Kanyembo (Author) / Kavazanjian, Edward (Thesis advisor) / Houston, Sandra (Committee member) / Zapata, Claudia (Committee member) / Arizona State University (Publisher)
Created2011
Description
The influence of temperature on soil engineering properties is a major concern in the design of engineering systems such as radioactive waste disposal barriers, ground source heat pump systems and pavement structures. In particular, moisture redistribution under pavement systems might lead to changes in unbound material stiffness that will affect pavement performance. Accurate measurement of thermal effects on unsaturated soil hydraulic properties may lead to reduction in design and construction costs. This thesis presents preliminary results of an experimental study aimed at determining the effect of temperature on the soil water characteristic curve (SWCC) and the unsaturated hydraulic conductivity function (kunsat). Pressure plate devices with volume change control were used to determine the SWCC and the instantaneous profile method was used to obtain the kunsat function. These properties were measured on two fine-grained materials subjected to controlled temperatures of 5oC, 25oC and 40oC. The results were used to perform a sensitivity analysis of the effect of temperature changes on the prediction of moisture movement under a covered area. In addition, two more simulations were performed where changes in hydraulic properties were done in a stepwise fashion. The findings were compared to field measured water content data obtained on the subgrade material of the FAA William Hughes test facility located in Atlantic City. Results indicated that temperature affects the unsaturated hydraulic properties of the two soils used in the study. For the DuPont soil, a soil with high plasticity, it was found that the water retention was higher at low temperatures for suction levels lower than about 10,000 kPa; while the kunsat functions at the three temperatures were not significantly different. For the County soil, a material with medium plasticity, it was found that it holds around 10% more degree of saturation at 5°C than that at 40°C for suction levels higher than about 1,000 kPa; while the hydraulic conductivity at 40°C was at least one order of magnitude higher than that at 5°C, for suction levels higher than 1,000 kPa. These properties were used to perform two types of numerical analyses: a sensitivity analysis and stepwise analysis. Absolute differences between predicted and field measured data were considered to be acceptable, ranging from 4.5% to 9% for all simulations. Overall results show an improvement in predictions when non-isothermal conditions were used over the predictions obtained with isothermal conditions.
ContributorsLu, Yutong (Author) / Zapata, Claudia E (Thesis advisor) / Kavazanjian, Edward (Committee member) / Houston, Sandra L. (Committee member) / Arizona State University (Publisher)
Created2015
Description
This dissertation details an attempt to experimentally evaluate the Giroud et al. (1995) concentration factors for geomembranes loaded in tension perpendicular to a seam by laboratory measurement. Field observations of the performance of geomembrane liner systems indicates that tears occur at average strains well below the yield criteria. These observations have been attributed, in part, to localized strain concentrations in the geomembrane loaded in tension in a direction perpendicular to the seam. Giroud et al. (1995) has presented theoretical strain concentration factors for geomembrane seams loaded in tension when the seam is perpendicular to the applied tensile strain. However, these factors have never been verified. This dissertation was prepared in fulfillment of the requirements for graduation from Barrett, the Honors College at Arizona State University. The work described herein was sponsored by the National Science Foundation as a part of a larger research project entitled "NEESR: Performance Based Design of Geomembrane Liner Systems Subject to Extreme Loading." The work is motivated by geomembrane tears observed at the Chiquita Canyon landfill following the 1994 Northridge earthquake. Numerical analysis of the strains in the Chiquita Canyon landfill liner induced by the earthquake indicated that the tensile strains, were well below the yield strain of the geomembrane material. In order to explain why the membrane did fail, strain concentration factors due to bending at seams perpendicular to the load in the model proposed by Giroud et al. (1995) had to be applied to the geomembrane (Arab, 2011). Due to the localized nature of seam strain concentrations, digital image correlation (DIC) was used. The high resolution attained with DIC had a sufficient resolution to capture the localized strain concentrations. High density polyethylene (HDPE) geomembrane samples prepared by a leading geomembrane manufacturer were used in the testing described herein. The samples included both extrusion fillet and dual hot wedge fusion seams. The samples were loaded in tension in a standard triaxial test apparatus. to the seams in the samples including both extrusion fillet and dual hot wedge seams. DIC was used to capture the deformation field and strain fields were subsequently created by computer analysis.
ContributorsAndresen, Jake Austin (Author) / Kavazanjian, Edward (Thesis director) / Gutierrez, Angel (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
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 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.
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.
ContributorsCuret, Dylan Shea (Author) / Kavazanjian, Edward (Thesis director) / Houston, Sandra (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Nanotechnology has been applied to many areas such as medicine, manufacturing, catalysis, food, cosmetics, and energy since the beginning 21st century. However, the application of nanotechnology to geotechnical engineering has not received much attention. This research explored the technical benefits and the feasibility of applying nanoparticles in geotechnical engineering. Specific studies were conducted by utilizing high-pressure devices, axisymmetric drop shape analysis (ADSA), microfluidics, time-lapse technology, Atomic Force Microscopy (AFM) to develop experiments. The effects of nanoparticle on modifying interfacial tension, wettability, viscosity, sweep efficiency and surface attraction forces were investigated. The results show that nanoparticles mixed in water can significantly reduce the interfacial tension of water in CO2 in the applications of nanofluid-CO2 flow in sediments; nanoparticle stabilized foam can be applied to isolate contaminants from clean soils in groundwater/soil remediation, as well as in CO2 geological sequestration or enhanced oil/gas recovery to dramatically improve the sweep efficiency; nanoparticle coatings are capable to increase the surface adhesion force so as to capture migrating fine particles to help prevent clogging near wellbore or in granular filter in the applications of oil and gas recovery, geological CO2 sequestration, geothermal recovery, contaminant transport, groundwater flow, and stormwater management system.
ContributorsZheng, Xianglei (Author) / Jang, Jaewon (Thesis advisor) / Zapata, Claudia (Committee member) / Kavazanjian, Edward (Committee member) / Arizona State University (Publisher)
Created2016
Description
This study evaluates the use of plant-extracted silica solution as a bio-based grout material for improvement of granular soils. Although silicate grout is a very well-established and popular technique in the ground improvement market, efforts have been initiated to replace chemically-synthesized silicate grout with plant-extracted silica grout. This initiative will increase the level of sustainability and consequently improve the existing market acceptability. The silica-rich plant source used for extraction was rice husk, which is an abundantly produced agricultural waste. The extraction method includes acid-leaching, temperature-controlled rice husk ash production and the preparation of an aqueous sodium silicate solution from the ash through an alkaline leachate method. Silica ash was in amorphous form containing 95% of silica content which is suitable for soil treatment. Gelation time was controlled in the absence and presence of sand under different pH values. Bio-based silica grouting showed an improvement of the shear strength of the soil as well as the hydraulic conductivity reduction.
ContributorsSayed Mostafa, Ahmad (Author) / Zapata, Claudia (Thesis advisor) / Khodadaditirkolaei, Hamed (Thesis advisor) / Kavazanjian, Edward (Committee member) / Arizona State University (Publisher)
Created2019