Engineering Commons^™

Utilizing The Hvsr Second Peak For Surface Wave Inversions In The Mississippi Embayment, Ashraf Kamal Himel

Graduate Theses and Dissertations

Ambient noise data from 24 sites within the Mississippi Embayment were analyzed to estimate the fundamental frequency using the horizontal to vertical spectral ratio (HVSR) method. The fundamental frequency ranged from 0.17 to 3.43 Hz for the tested sites. At seventeen of the sites, a second higher frequency HVSR peak, which ranged from 0.617 Hz to 2.154 Hz, was observed in addition to the fundamental HVSR peak. The second peak frequency in the HVSR curve has been attributed by previous researchers as either an odd harmonic of the fundamental peak or a shallow impedance contrast from the Memphis sand layer …

Examining The Use Of Idealized Granular Material In Validated Dem Simulations, Anjana Thoroppady Kittu

Graduate Theses and Dissertations

Discrete element method (DEM) modeling, is becoming widely used for understanding the micro-mechanical behavior of granular materials at the particle level. This dissertation presents important considerations regarding the experimental boundary conditions and idealized granular materials used in DEM validations.

A common issue in DEM validation studies for direct shear and direct simple shear is selecting top and bottom cap boundary conditions that allow for shear transmission while also being efficiently modeled in the DEM simulations. While the traditional grid boundary types used in the laboratory can be replicated in the numerical models, researchers have also used fixed-particle boundaries, sawtooth boundaries, …

Controlling Relative Humidity Using Glycerin, Juan Martinez

Civil Engineering Undergraduate Honors Theses

A series of tests were conducted to control relative humidity (RH) using a bubbler system that contained a series of glass jars and glass vials filled with different concentrations of glycerin. The relative humidity within the glass jars was measured. The total time interval for each laboratory test was 48 hours. During the first 24 hours a pump was used to bubble air through the glycerin solution. During the second 24 hours, the pump was turned off, and the RH within the system was monitored within the closed system. Target RH measurements from 100% to a 0% were obtained. The …

Utilizing 3d Printed Analogue Soils To Investigate Specimen Size Effects In Triaxial Testing, Claire Louise Stewart

Graduate Theses and Dissertations

Triaxial testing is one of the fundamental laboratory tests used in geotechnical engineering to determine strength parameters, such as shear strength and friction angle. Investigating the minimum representative elementary volume (REV) can verify the independence of size effects on strength parameters and ensure that the scaled laboratory tests results are consistent, repeatable, and representative of field conditions. Although, REV has been studied for many applications, there is disagreement within geotechnical engineering of a minimum particle diameter to specimen diameter to minimize the size effects related to the REV in consolidated drained (CD) triaxial tests. This research study compared the strength …

Young’S Modulus As A Measurement To Estimate Damage Related With Alkali-Silica Reaction In Concrete., Anazaria J. Ortega Gonzalez

Civil Engineering Undergraduate Honors Theses

The main purpose of this research is to compare two nondestructive methods to assess Alkali-Silica reaction (ASR) in concrete. Fifteen concrete prisms were cast using aggregates with different Alkali-Silica reactivity such as Jobe sand and Van Buren sand. The change in strain, shear wave velocity and Young’s modulus were determined according to ASTM C129 and ASTM C215, respectively. This data was collected by Dillon K Self, who determined that the shear wave velocity and strain are inversely proportional. However, when single cracking in the concrete specimen transition to map cracking, the shear wave velocity dropped significantly, whereas the strain value …

Evaluation Of A Centrifuge Consolidation Technique To Determine The Effects Of Temperature And Time On Kaolinite Properties, Esteban Miranda Pinzon

Civil Engineering Undergraduate Honors Theses

Abstract

The effects of time and temperature on the moisture content and unit weight profiles, as developed during a centrifuge consolidation process, were observed during the research program that is described herein. Specifically, a Beckman-Coulter Model J6-MI centrifuge with a six-place JS-4.2A swinging bucket rotor was utilized to consolidate kaolinite slurry samples. The consolidation procedure utilized specially designed slurry consolidometers, made from acrylic tubes with inside diameters of 2.63 inches (6.67 cm) and heights of 5.13 inches (13.04 cm). The tested kaolinite slurry samples were created by mixing 400 grams of dry kaolinite clay powder with 200 grams of de-aired …

The Intrinsic Properties Of Reconstituted Soils, Nabeel Shaker Mahmood

Graduate Theses and Dissertations

Reconstituted specimens are often utilized to characterize engineering properties of cohesive soils. A series of undrained triaxial tests were conducted on reconstituted soil specimens to evaluate 1) the influence of stress path, 2) the intrinsic shear strength behavior, and 3) the small-strain characteristics. The stress path tests were conducted on kaolinite specimens reconstituted from slurries with water content values of one and one-half times the liquid limit of the soil (1.5LL). To evaluate the intrinsic undrained shear strength and the intrinsic small-strain properties, the triaxial tests were performed on kaolinite and illite specimens that were reconstituted at two levels of …

Liquefaction-Induced Dragload And/Or Downdrag On Deep Foundations Within The New Madrid Seismic Zone, Ishimwe Elvis

Graduate Theses and Dissertations

Deep foundation elements are typically used to transfer structural loads for multi-story buildings and large-span bridges to a competent soil layer when 1) the soil close to the ground surface has no sufficient bearing capacity, and when 2) liquefiable soils are encountered. The majority of the bridges constructed within seismic zones rely upon the stability of earthen embankments and deep foundation that are installed above or within liquefiable soil deposits. Despite large factor of safety values or different load and resistance factors being used to adequately design deep foundations within seismic areas, soil liquefaction may cause extensive damage to the …

Development Of A Hydraulic Conductivity Placement Window Using Centrifuge Techniques, Greg Thomas

Civil Engineering Undergraduate Honors Theses

A centrifuge soil testing device, currently operated by researchers at the University of Arkansas, was used to develop a technique to determine a hydraulic conductivity placement window. The purpose of this research was to develop a placement window by means of a centrifuge instead of by means of a panel board. Soil specimens were created at standard PRcotor energy and at 50 percent of Standard Proctor energy at -3 percent of optimum, -1.5 percent of optimum, two specimens at optimum, +1.5 percent of optimum, and +3 percent of optimum water content. Values of hydraulic conductivity for the respective specimens were …