Engineering Commons^™

Using Quantitative Stereology On High Resolution Sem Images To Estimate Diatom Percentages, Ariadna Covarrubias Ornelas

Dissertations and Theses

Diatoms are single-celled organisms of various shapes and sizes typically found in aquatic environments. When diatoms die, the organic material decomposes, and the outer skeletons (i.e., frustules) settle and accumulate as sedimentary deposits. These soils, called diatomaceous soils, exhibit nontraditional behavior since the diatom particles are typically hollow skeletons composed of amorphous silica with intricately patterned and abrasive surfaces. Recent studies have shown that diatomaceous soils are challenging geomaterials since even a small percentage of diatom particles will notably affect engineering behavior. Furthermore, laboratory studies on diatomaceous soil mixtures have demonstrated that many engineering soil properties depend on the percentage …

Field Trials And Long-Term Monitoring Of Microbially-Induced Desaturation For The Treatment Of Liquefiable Silty Soils, Kayla Rae Sorenson

Dissertations and Theses

Earthquake liquefaction hazards in silty soils are a critical problem in Portland, Oregon, and other areas around the world. This is a particular problem for existing facilities founded on liquefiable soils, for which there exists no cost-effective liquefaction mitigation solution at the present time. It is essential from both a seismic safety and a seismic resilience perspective to be able to mitigate potentially liquefiable soils underneath existing structures, and to do so in a cost-effective manner. Recent studies suggest that liquefaction mitigation using microbially-induced desaturation (MID) may provide this capability.

The objective of MID is to reduce earthquake-induced excess pore …

An Analysis Of Suspended Sediment Dynamics In A Partially Mixed Estuary, Riyadh Hamad Muttaleb

Dissertations and Theses

The purpose of this work is to investigate via data analysis and numerical modeling the SPM (suspended particulate matter) dynamics of a heavily contaminated partially urban estuary, the Lower Passaic River estuary (LPR), NJ. Accordingly, I investigate the quantity and mechanics of variation of fine and coarse SPM in the LPR via data analysis. Data analysis focuses on the parameters that affect SPM dynamics at six moored stations occupied during the Fall and Spring seasons, from near the estuary mouth to tidal freshwater. A 3D hydrodynamic model (Delft3D-FM) is used to analyze the effects of estuary topography on the dynamic …

Mit-S1 Constitutive Model Calibration For A Portland-Area Soil, Steven Ryan Young

Dissertations and Theses

Soils that are intermediate to sands and clays are a challenge for geotechnical engineers since most methods for interpreting soil properties or soil behaviors are based on sands or clays and do not address behaviors of intermediate soils. This is a particular challenge for engineers in the Portland-area where many of the major soil units are composed of intermediate soils. Analysis of intermediate soils is further challenged since many standard constitutive models are based on sandy or clay-like soils. However, the MIT-S1 constitutive model is capable of capturing intermediate soil behavior. A calibration of the MIT-S1 constitutive model for Portland-area …