### Recent Submissions

• #### Hydrodynamics of downstream pointed guidevanes: a case study of the Hess Creek meander bend realignment

The hydrodynamics of downstream pointed guidevanes installed to realign an eroding meander bend upstream of the Trans- Alaska Pipeline bridge is studied. The bridge is located at Hess Creek, 137 km north of Fairbanks, Alaska. Effect of the downstream pointed vanes on bed form, erosion, longitudinal and transverse slopes, three dimensional velocity profiles, flow patterns, and other hydraulic parameters for high and low flows are compared and analyzed. Six years after installation of the vanes the realigned thalweg remains in its original design location. The longitudinal bed profile changed from a dominant continuous pool typical of natural meander bends on gravel stream beds to a series of pool riffles. However, there is minimal change in maximum scour depth between post and pre installation of the vanes. Secondary or transverse current patterns which cause scour or erosion on the outer bank are severely disrupted due to interference caused by the vanes. There is a consistent weak counter current in reaches between the vane stems due to flow separation caused by expansion of flow area. This condition was more dominant during low flows when the vanes were not completely submerged. From the tip of the vanes to the inner bank a more dominant transverse and streamwise current was measured. Location of the original eroding outer bank remains unchanged since installation of the vanes. This indicates that the vanes have to this point effectively realigned the meander bend and arrested additional lateral movement of the meander.
• #### Creep of grouted anchors in ice-rich silt

Creep is a critical consideration for designing anchors in ice-rich silt. In this study, creep was evaluated for grouted anchors in ice-rich silt by laboratory tests. A total of nineteen staged-load pullout tests were conducted on smooth grouted anchors. The anchors were loaded until either a tertiary creep stage or the capacity of the load system was reached. Soil temperatures evaluated in this study ranged from 32 °F to 26.6 °F. It was found that the onset of tertiary creep for smooth anchors was around 0.03 inches, which was much smaller than that suggested in the literature for rough anchors (1.0 inch). Given the same shear stress and soil temperature, the observed creep displacement rates for smooth anchors were greater than those given by the existing design guidelines for rough anchors. A new creep model was proposed in which soil temperature was included as an additional variable. Model parameters were developed as a function of soil temperature and moisture contents by using the test data. The model predictions were compared with the laboratory tests. It was found that the creep displacement rates decreased with the decreasing of soil moisture contents and temperature. Based on the analysis of laboratory test data, design charts were provided to give the allowable pullout capacity for smooth anchors in ice-rich silt.
• #### Attenuation of the herbicide glyphosate along railroad corridors in Alaska

Following the application of glyphosate in the formulation of AquaMaster® at two contrasting sub-arctic zones along the railroad corridor in Alaska, attenuation of the herbicide glyphosate was investigated. Study sites were established in continental and coastal zones. Glyphosate soil attenuation was similar to temperate regions during the growing season but exhibited an extended persistence during the winter months. Although glyphosate microbial degradation likely slowed during winter, both sites showed evidence of slight glyphosate degradation during the winter months. The coastal site attenuated more rapidly than the continental site which is presumably due to increased rainfall relative to the continental site. Glyphosate attenuation at the coastal site was likely driven by dispersion while microbial degradation was responsible for the attenuation of glyphosate at the continental site. Movement to subsurface soils (10-25 cm) at low concentrations was observed at both sites with slightly more transport at the coastal site than the continental site. Glyphosate transport to groundwater along railroad corridors was not conclusive. Vegetation cover reduction was reduced at the continental site but could not be determined at the coastal site.

Western Alaska lacks gravel suitable for construction of roads and airports. As a result, gravel is imported, at a cost of between $200 and$600 per cubic yard, to fill transportation construction needs. In an effort to reduce these costs, the Alaska University Transportation Center (AUTO) began searching for methods to use local materials in lieu of imported gravel. The approach discussed in this thesis uses geofibers and chemical additives to achieve soil stabilization. Geofibers and chemical additives are commercially available products. The goal of the research presented in this thesis is to test the impact of addition of two geofiber types, six chemical additives, and combinations of geofibers with chemical additives on a wide variety of soil types. California Bearing Ratio (CBR) testing was used to measure the effectiveness of the treatments. Soils ranging from poorly graded sand (SP) to low plasticity silt (ML) were all effectively stabilized using geofibers, chemical additives, or a combination of the two. Through the research conducted a new method of soil stabilization was developed which makes use of curing accelerators in combination with chemical additives. This method produced CBR values above 300 for poorly graded sand after a seven day cure.
• #### Characterizing the berthing load environment of the Seattle ferry teminal, Bremerton slip

This manuscript characterizes and presents design recommendations for berthing demands on ferry landing structures. There is a lack of research focused on the berthing load demand imparted by ferry class vessels, therefore the load criteria used for design is often based on a number of assumptions. This study involved a one-year field study of the structural load environment of wingwalls at the Bremerton Slip of the Seattle Ferry Terminal, located in Elliott Bay adjacent to Seattle, Washington. Measurements of marine fender displacement, vessel approach distance with respect to time, and. pile strain were used to determine berthing demands. Berthing event parameters were characterized using the Python programming language, compiled, and analyzed statistically. Probability theory was used to provide design value recommendations for berthing energy, force, approach velocity, berthing factor, and berthing coefficient. This study presents a number of engineering design aids intended to quantify the berthing load environment of wingwalls in the Washington State Ferry System.
• #### Evaluating dust palliative performance and longevity using the UAF-DUSTM

Fugitive dust emissions from gravel surfaces such as unpaved roads and airport runways are a major source of particulate matter pollution in the environment. Fugitive dust emissions impact community health, decrease visibility and contribute to surface degradation. Chemical additives, also known as dust palliatives, are often used to reduce these dust emissions. Although these products have been widely used, little is known about their effectiveness and longevity. There is currently no standard test method to quantify the reduction in fugitive dust emissions provided by dust palliatives. The UAF-DUSTM was developed to provide a consistent test method for determining the effectiveness and longevity of dust palliative applications. Dust palliatives applications throughout Alaska were monitored for several years. The results show that dust palliatives can significantly reduce particulate matter emissions and be effective for several years.
• #### The impact of a fluctuating freezing front on ice formation in freezing soil

Frost heave is typically associated with the formation of segregation ice in fine-grained soil. Coarse-grained soil is generally considered to be non-frost susceptible. Field observa-tions and laboratory experiments show that coarse-grained soil can be extremely ice-rich in specific conditions. Previous studies have shown that oscillation of the frozen-unfrozen boundary can lead to the formation of ice by a mechanism different from the segregation ice mechanism. Conditions related to the formation of ice in coarse-grained soil were in-vestigated using modern laboratory techniques. Fourteen tests were conducted on five soil types. The thickness of soil subjected to freeze-thaw cycles was varied and controlled by the magnitude and duration of applied soil temperatures. The thickness of the ice formed increased when the sample drainage was limited or prevented during cooling. Under spe-cific conditions, the formation of a discrete ice layer was observed in coarse-grained soils. Seven samples were scanned with the pCT scanner at the completion of the warming and cooling tests. The sub-samples scanned were analyzed in 2D cross-sections, and charac-terized as 3D reconstructions. Frost heave induced by the formation of ice was observed in both fine- and coarse-grained soils, including soils that were found to be traditionally non-frost susceptible.
• #### The role of tundra vegetation in the Arctic water cycle

Vegetation plays many roles in Arctic ecosystems, and the role of vegetation in linking the terrestrial system to the atmosphere through evapotranspiration is likely important. Through the acquisition and use of water, vegetation cycles water back to the atmosphere and modifies the local environment. Evapotranspiration is the collective term used to describe the transfer of water from vascular plants (transpiration) and non-vascular plants and surfaces (evaporation) to the atmosphere. Evapotranspiration is known to return large portions of the annual precipitation back to the atmosphere, and it is thus a major component of the terrestrial Arctic hydrologic budget. However, the relative contributions of dominant Arctic vegetation types to total evapotranspiration is unknown. This dissertation addresses the role of vegetation in the tundra water cycle in three chapters: (1) woody shrub stem water content and storage, (2) woody shrub transpiration, and (3) partitioning ecosystem evapotranspiration into major vegetation components. In Chapter 1 I present a method to continuously monitor Arctic shrub water content. The water content of three species (Salix alaxensis, Salix pulchra, Betula nana) was measured over two years to quantify seasonal patterns of stem water content. I found that spring uptake of snowmelt water and stem water storage was minimal relative to the precipitation and evapotranspiration water fluxes. In Chapter 2, I focused on water fluxes by measuring shrub transpiration at two contrasting sites in the arctic tundra of northern Alaska to provide a fundamental understanding of water and energy fluxes. The two sites contrasted moist acidic shrub tundra with a riparian tall shrub community having greater shrub density and biomass. The much greater total shrub transpiration at the riparian site reflected the 12-fold difference in leaf area between the sites. I developed a statistical model using vapor pressure deficit, net radiation, and leaf area, which explained >80% of the variation in hourly shrub transpiration. Transpiration was approximately 10% of summer evapotranspiration in the tundra shrub community and a possible majority of summer evapotranspiration in the riparian shrub community. At the tundra shrub site, the other plant species in that watershed apparently accounted for a much larger proportion of evapotranspiration than the measured shrubs. In Chapter 3, I therefore measured partitioned evapotranspiration from dominant vegetation types in a small Arctic watershed. I used weighing micro-lysimeters to isolate evapotranspiration contributions from moss, sedge tussocks, and mixed vascular plant assemblages. I found that mosses and sedge tussocks are the major constituents of overall evapotranspiration, with the mixed vascular plants making up a minor component. The potential shrub transpiration contribution to overall evapotranspiration covers a huge range and depends on leaf area. Predicted increases in shrub abundance and biomass due to climate change are likely to alter components of the Arctic hydrologic budget. The thermal and hydraulic properties of the moss and organic layer regulate energy fluxes, permafrost stability, and future hydrologic function in the Arctic tundra. Shifts in the composition and cover of mosses and vascular plants will not only alter tundra evapotranspiration dynamics, but will also affect the significant role that mosses, their thick organic layers, and vascular plants play in the thermodynamics of Arctic soils and in the resilience of permafrost.

• #### Establishing and testing detection methods for anti-icing and deicing chemicals using spectral data

Snow and ice accumulation on pavement reduce roadway surface friction and consequently result in diminished vehicle maneuverability, slower travel speeds, reduced roadway capacity, and increased crash risk. Though the use of chlorides and other freeze-inhibiting substances have been shown to reduce these negative factors, methods to quantify and analyze snow and ice remediation methods as well as the imposed loss of material are needed to allow state and municipal agencies to better allocate winter maintenance resources and funding. The use and application of chlorides, sand, and their related mixtures have proven to be highly effective for controlling or removing the development of ice on the roadway surface. However, if the amount of salt in solution becomes too dilute, then it no longer retains the capacity to control the development of, or to melt, ice on the roadway and may prove to be more detrimental by allowing the previously melted material to refreeze with a smoother (i.e., more slippery) surface state. The goal of this project was to determine to what extent winter roadway surfaces can be analyzed using spectrometry to determine the longevity and coverage of various types of applications. Using a systematically paired analysis of changes in spectrometric curves as solution concentrations change, relationships were generated which detected change in deicing and anti-icing compounds reliably in a lab setting. Field results were less reliable, suggesting that further comparisons and a more in-depth spectral library are needed.
• #### Snowmelt hydrology in the upper Kuparuk watershed, Alaska: observations and modeling

The Fourth National Climate Assessment Report (2018) indicates that Alaska has been warming at a rate two times greater than the global average with the Arctic continuing to be experiencing higher rates of warming. Snowmelt driven runoff is the largest hydrologic event of the year in many Alaska Arctic river systems. Changes to air temperature, permafrost, and snow cover impact the timing and magnitude of snowmelt runoff. This thesis examines the variability in hydrometeorological variables associated with snowmelt to better understand the timing and magnitude of snowmelt runoff in headwater streams of Arctic Alaska. The objectives of this thesis are to: (1) use observational data to evaluate trends in air temperature, precipitation, snow accumulation, and snowmelt runoff data; (2) relate precipitation, snow cover, and air temperature to snowmelt runoff using the physically-based Snowmelt Runoff Model (SRM) to test the applicability of the model for headwater streams in the Arctic. The focus of this study is the Upper Kuparuk watershed area, located in Alaska on the north side of the Brooks Range, where several monitoring programs have operated long enough to generate a 20-year climate record, 1993-2017. Long-term air temperature, precipitation, and streamflow data collected by the University of Alaska Fairbanks at the Water and Environmental Research Center and other agencies were used for statistical analysis and modeling. While no statistically significant trends in snow accumulation and snowmelt runoff were identified during 1993-2017, observations highlight large year-to-year variability and include extreme years. Snow water equivalent ranges from 5.4 to 17.6 cm (average 11.0 cm), peak snowmelt runoff ranges from 3.84 to 50.0 cms (average 22.4 cms), and snowmelt peak occurrence date ranges from May 13 to June 5 for the Upper Kuparuk period of record. The spring of 2015 stands out as the warmest, snowiest year on record in the Upper Kuparuk. To further investigate the runoff response to snowmelt in 2015, remote sensing snow data was analyzed and recommended parameters were developed for SRM use in the Upper Kuparuk watershed. Recommended parameters were then applied to 2013 snowmelt runoff as a test year. Model results varied between the two years and provide good first-order approximation of snowmelt runoff for headwater rivers in the Alaska Arctic.
• #### Pre-stress loss due to creep in precast concrete decked bulb-tee girders under cold climate conditions

This report presents guidelines for estimating pre-stress loss in high-strength precast pretensioned concrete Decked Bulb-Tee (DBT) bridge girders in cold climate regions. The guidelines incorporate procedures yielding more accurate predictions of shrinkage and concrete creep than current 2017 American Association of State Highway and Transportation Officials (AASHTO) specifications. The results of this report will be of particular interest to researchers and cold climate bridge design engineers in improved predictions of design life and durability. The use of high-strength concrete in pre-tensioned bridge girders has increased in popularity among many state highway agencies. This fact is due to its many beneficial economic and constructability aspects. The overall cost of longer girders with increased girder spacing in a bridge that is precast with high strength concrete can be significantly reduced through the proper estimating factors. Recent research indicates that the current provisions used for calculating prestress losses in cold regions for high-strength concrete bridge girders may not provide reliable estimates. Therefore, additional research is needed to evaluate the applicability of the current provisions for estimating pre-stress losses in high-strength concrete DBT girders. Accurate estimations of pre-stress losses in design of pre-tensioned concrete girders are affected by factors such as mix design, curing, concrete strength, and service exposure conditions. The development of improved guidelines for better estimating these losses assists bridge design engineers for such girders and provide a sense of security in terms of safety and longevity. The research includes field measurements of an environmentally exposed apparatus set up to measure shrinkage, creep and strain in cylinders loaded under constant pressure for a full calendar year.
• #### Numerical simulation of thermo-mechanical behavior of gypsum board wall assembly

Fire safety has become a significant concern to public safety; especially in the aftermath of 9/11 attack where, according to official reports, three World Trade Center buildings collapsed because of fire. Therefore, the level of thermal insulation required from building material and structural elements has increased. In recent years, gypsum board wall assemblies have been increasingly used as compartmentation for high-rise residential and commercial buildings. The increasing popularity of gypsum board wall assemblies is due to their relatively high strength-to-weight ratio, ease of prefabrication, fast erection and good thermal insulation. Before implementation of any building material or structural element, its Fire Resistance Rating must be determined by subjecting the material or element to a standard furnace fire test. Over the years, a large database has been collected for the Fire Resistance Rating of building materials and structural elements. However, due to the expensive and time-consuming nature of the standard fire tests, determining an accurate Fire Resistance Rating can be a difficult task. In this study, the author numerically evaluated the Fire Resistance Rating of a new gypsum board wall assembly. Composite steel-EPS (Expanded Polystyrene) insulation is added to a traditional gypsum board wall assembly. The author first did numerical simulation of an experiment on the thermal response of a non-load-bearing gypsum board wall assembly to verify the thermal modeling methodology. The author then did numerical simulation of an experiment on the mechanical response of a load-bearing gypsum board wall assembly to verify the mechanical modeling methodology. Finally, the author used the verified thermal and structural modeling methodology to simulate the new composite steel-EPS gypsum board wall assembly and obtained its numerical Fire Resistance Rating. This Fire Resistance Rating should be compared with future experimental results of the new wall assembly. All modeling was done with ABAQUS V6.14.
• #### 2-D bed sediment transport modeling of a reach on the Sagavanirktok River, Alaska

Conducting a 2-D sediment transport modeling study on the Sagavanirktok River has offered great insight to bed sediment movement. During the summer of 2017, sediment excavation of two parallel trenches began in the Sagavanirktok River, in an effort to raise the road elevation of the Dalton Highway to remediate against future floods. To predict the time in which the trenches refill with upstream sediment a 2-D numerical model was used. Three scenarios: (1) a normal cumulative volumetric flow, (2) a max discharge event, and (3) a max cumulative volumetric flow, were coupled with three sediment transport equations: Parker, Wilcock-Crowe and Meyer Peter and Müller for a total of 9 simulations. Results indicated that scenario (1) predicted the longest time to fill, ranging from 1-6 years followed by scenario (2), an even shorter time, and scenario (3) showing sustained high flows have the capability to nearly refill the trenches in one year. Because the nature of this research is predictive, limitations exist as a function of assumptions made and the numerical model. Therefore, caution should be taken in analyzing the results. However, it is important to note that this is the first time estimates have been calculated for an extraction site to be refilled on the Sagavanirktok River. Such a model could be transformed into a tool to project filling of future material sites. Ultimately, this could expedite the permitting process, eliminating the need to move to a new site by returning to a site that has been refilled from upstream sediment.

• #### An evaluation of the use of moderate resolution imaging spectroradiometer (MODIS)-derived aerosol optical depth to estimate ground level PM2.5 in Alaska

Under repeated external loads, engineering structures or objects may fail by large plastic deformation or fatigue. Shakedown will occur when the accumulation of plastic deformation ceases under repeated loads; the response of the system is then purely elastic. Fatigue and shakedown have been individually studied for decades and no attempt has been made to couple these two mechanisms in the mechanics analysis. In this study, an attempt is made to couple shakedown and fatigue in pavement mechanics analysis using numerical simulation. The study covers three main areas: fatigue, static shakedown, and kinematic shakedown analysis. A numerical approach to fatigue analysis is proposed based on elastic-plastic fracture mechanics. The amount of the crack growth during each load cycle is determined by using the J-integral curve and $\rm R\sb{-}curve.$ Crack propagation is simulated by shifting the $\rm R\sb{-}curve$ along the crack growth direction. Fatigue life is predicted based on numerically estabiished fatigue equation. The numerical results indicate that the algorithm can be applied to fatigue analyses of different materials. A numerical algorithm based on the finite element method coupled with the nonlinear programming is proposed in static shakedown analysis. In this algorithm, both the inequality and equality constraints are included in the pseudo-objective function. These constraints are normalized by the material yield stress and the reference load, respectively. A multidirectional search algorithm is used in the optimization process. The influence of finite element mesh on shakedown loads is investigated. An algorithm that utilizes eigen-mode to construct the arbitrary admissible plastic deformation path is proposed in kinematic shakedown analysis. This algorithm converts the shakedown theorem into a convex optimization problem and can be solved by using a multidirectional search algorithm. Fatigue behavior of a two-layer full-depth pavement system of asphalt concrete is analyzed using the proposed numerical algorithm. Fatigue crack growth rate is estimated and fatigue life is predicted for the system. Shakedown analyses are also carried out for the same pavement system. The comparison between the shakedown load and the fatigue failure load with respect to the same crack length indicates that the shakedown dominates the response of the pavement system under traffic load.