Gully erosion is a global problem that degrades land and reduces its utility for agriculture, development, and water quality. Quantification of sediment yield and control of sediment sources is essential for environmental protection. Five methods to evaluate erosion rates and sediment yield on an east Tennessee, USA, hillslope were compared: (1) physical measurement by removal of accumulated sediment using 10 L buckets; (2) repeated measurement of erosion pins in gully (erosional) and delta (depositional) areas; (3) geometric model using a combination trapezoidal prism-cylinder segment; (4) geometric model using a series of trapezoidal pyramids; and (5) 3D solid computer modeling. The 3D solid model created in SolidWorks was selected as the reference model and all other methods overestimated sediment yield to varying degrees. Erosion pin methods overestimated sediment yield by 368% in deltas and 123% in gullies. Volumetric measurement of sediment using buckets overestimated sediment yield by 160% due to void space in the buckets. The trapezoidal prism-cylinder segment model overestimated sediment yield by 66% and the trapezoidal pyramids method overestimated sediment yield by 5.7%. For estimation of sediment trapped behind an elliptical or circular silt fence dam, use of the trapezoidal pyramid method provides a good approximation comparable to 3D solid computer modeling.

Atlantic Meridional Overturning Circulation (AMOC) is a vital process that transfers heat and nutrients throughout the world's oceans, helping to regulate global climate and support marine ecosystems. The timing and nature of the shift to modern AMOC, and especially to deep-water formation in the North Atlantic, has been a topic of ongoing study, with the Eocene-Oligocene Transition (EOT, ~34 Ma) as a potential focal point of this shift. However, the role played by abrupt EOT cooling and Antarctic glaciation in North Atlantic circulation remains unclear. Improved constraints on Paleogene circulation will provide insight into the sensitivity of AMOC to perturbations in global climate, which is particularly relevant in light of contemporary climate change. To examine deep North Atlantic circulation response to the EOT we obtained grain-size data from the terrigenous fraction of the mud-dominated sediments of the Southeast Newfoundland Ridge contourite drift complex at IODP Site U1411, which is interpreted to have formed under the influence of the Deep Western Boundary Current. We analyzed 195 samples that span 150 m of stratigraphy from 36-26 Ma. The main objective was to use the 'sortable silt' fraction (10-63 µm) to generate a record of relative change in bottom-current intensity. These data are complemented with a record of the abundance and size of lithogenic sand (>63 µm). Here we present the first physical proxy record of abyssal current intensity in the North Atlantic, from late Eocene to mid Oligocene. Invigoration of North Atlantic deep circulation occurred gradually (over Myr timescales), with no significant changes linked temporally to the EOT. We infer that deep circulation in the North Atlantic was not sensitive to the abrupt global cooling and Antarctic glaciation associated with the EOT. Rather, our data suggest that changes in North Atlantic circulation were likely governed by longer-term processes related to the opening of key tectonic gateways, such as the Greenland-Scotland Ridge in the North Atlantic, and the Drake and Tasman Passages in the Southern Ocean. Additionally, we identify a significant mid-Oligocene invigoration of North Atlantic abyssal circulation, which climaxes around 27.9 Ma, and is coeval with a decrease in atmospheric CO2. / Master of Science

Frost heave damage to roadways costs millions of dollars every year. The need for an improved understanding of the fundamental mechanisms associated with frost heave and methods for efficiently improving frost-susceptible materials prompted the Department of Civil and Environmental Engineering at Brigham Young University (BYU) to undertake a project to design, construct, and verify the functionality of a new frost heave testing apparatus. Frost heave research has been carried out for more than 75 years. The equipment used to conduct this testing has advanced in accuracy and utility over the years. To establish a background in past and current frost heave research, a survey of 12 frost heave devices, including their construction and capabilities, was performed in this research. Several design objectives were then delineated, and a nine-specimen frost heave device was designed and constructed to meet the specifications. The apparatus uses one collective heat source and one collective heat sink for all nine specimens. Heave data and temperature data are collected electronically, while the weights of the specimens before and after frost heave testing are measured manually. Preparatory tests were conducted to confirm the functionality of the data acquisition systems, the uniformity of conditions experienced by all specimens, and the replication of natural roadway freezing conditions. Once preparatory testing was complete, a full-scale frost heave test was performed using the apparatus to investigate the efficacy of cement stabilization in reducing the frost susceptibility of a Montana silt and to validate the functionality of the finished device. Results from the testing indicate that adding 2.0 percent cement actually induces frost heave in excess of that exhibited by the untreated soil. However, additions of 3.5 percent and 5.0 percent were found to be effective in preventing frost heave. Although minor, recommendations for further improvements to the frost heave apparatus include provisions to further decrease the thermal gradient across the specimen and installation of an automatic temperature control device for the water source.

Each year in the United States, large volumes of material are dredged out of lakes and waterways and are dumped in confined disposal facilities so that they can consolidate. A mathematical model is proposed to predict the settling of the dredged material by predicting the ?primary? self-weight consolidation curve of silt particles under zone settling conditions. Using a relatively ?pure? specimen of silt, self-weight consolidation tests were performed at concentrations ranging from 10 to 200 grams per liter. To generate the predicted curve, the model requires the location of the zone interface at 180, 600, and 720 seconds and the assumed A-value. The A-value is used to ?fine-tune? the predicted curve so that it will fit the experimental curve. When values of ?A? from 0.85 to 0.95 are used, the predicted curve will fit the experimental curve for all concentrations considered. Thus, to predict the ?primary? self-weight consolidation of the dredged material, a sedimentation test using a sample of the dredged material must first be performed.

The stability of natural slopes is goverened by many factors, one of which is the porewater pressure. In this study, a sensitivity analysis has been conducted in GeostudioSLOPE/W to investigate the impact of near-surface pore water pressure on thefactor of safety i silt slopes. The study includes five slopes along Ångermanälven,Sweden, which previously have been investigated within the framework of a slopefailure risk mapping of the area conducted by the Swedish Geotechnical Institute,SGI. The near-surface pore water pressure in the slopes has not successfullybeen measured in this area as the slopes are very high and steep. Calculations ofslope stability done previously by Tyréns instead assumed 1) that the pore waterpressure is zero 1m in from the slope face and 2) that it decreases hydrostatically(10 kPa/m) towards the slope face, and these are the parameters studied in thesensitivity analysis. When the pore water pressure is set to zero at the surface, thefactor of safety is reduced by an average of 7 %. Setting the pore water pressure tozero 2mfrom the surace increases the safety factor by 3%on average. A lower thanhydrostatic (7 kPa/m) pore pressure gradient increases the safety factor by on average2 %. A higher than hydrostatic pore water gradient decreases the safety factorby 16% on average. The results verifies that an increase in near-surface pore waterpressure gives a lower factor of safety and decrease in near-surface pore waterpressure leads to a higher factor of safety. The slopes are generally more sensitiveto destabilizing changes of the near-surface pore water pressure than of those stabilizing.Other factors such as vegetation, cohesion, dilatancy and erosion are notconsidered in this study but likely have a considerable effect on the stability. Whenmodelling the influence of near-surface pore water pressure and other parameters,it is recommended to use a FEM program.

The presence of silt and clay particles has long been thought to affect the behavior of a sand under cyclic loading. Unfortunately, a review of studies published in the literature reveals that no clear conclusions can be drawn as to how altering fines content and plasticity actually affects the liquefaction resistance of a sand. In fact, the literature contains what appears to be contradictory evidence. There is a need to clarify the effects of fines content and plasticity on the liquefaction resistance of sandy soils, and to determine methods for accounting for these effects in engineering practice. In order to help answer these questions, a program of research in the form of a laboratory parametric study intended to clarify the effects which varying fines content and plasticity have upon the liquefaction resistance of sandy sands was undertaken. The program of research consisted of a large number of cyclic triaxial tests performed on two sands with varying quantities of plastic and non-plastic fines. The program of research also examined the applicability of plasticity based liquefaction criteria and the effects of fines content and plasticity on pore pressure generation. Lastly, a review of how the findings of this study may affect the manner in which simplified analyses are performed in engineering practice was made. The results of the study performed are used to clarify the effects of non-plastic fines content and resolve the majority of the inconsistencies in the literature. The effects of plastic fines content and fines plasticity are shown to be different than has been previously reported. The validity of plasticity based liquefaction criteria is established, the mechanism responsible for their validity is explained, and a new simplified criteria proposed. The effects of fines content and plasticity on pore pressure generation are discussed, and several recommendations are made for implementing the findings of this study into engineering practice. / Ph. D.

The decline in mussel fauna of the Powell River has been attributed to extensive mining activities in headwater streams of Wise and Lee counties, Virginia. Surface mining causes erosion, sedimentation, and contamination of water with toxic substances from coal washing and waste piles. Historical water quality data of the Powell River have documented concentrations of metals at levels determined to be toxic to molluscs, specifically zinc (Zn) and copper (Cu). Acute toxicity tests with Zn, Cu, and mixtures of these two metals were conducted with glochidia and juvenile freshwater mussels. Effects of varying conditions such as water source, temperature, length of exposure, species, and lifestage were determined. Additionally, the effects of Powell River sediment on survival and growth of juvenile mussels were evaluated. The Cumberland moccasin shell (Wedionidus conradicus) was the most sensitive species tested, with 24-hr and 48-hr LC50 values for glochidia ranging from 423 to 725 μg Zn/L. Glochidia of the pheasantshell (Actinonaias pectorosa) exhibited LC50 values from 274 to 2886 μg Zn/L, depending on test conditions. Similar results were obtained for glochidia of the rainbow (Villosa iris), with LC50 values ranging from 577 to 4123 μg Zn/L. Juveniles were more sensitive, with 48-hr LC50 values ranging from 360 to 1885 μg Zn/L for A. pectorosa, and 339 to 1122 μg Zn/L for V. iris, depending on test conditions. Juvenile mussels were affected by Zn at lower concentrations as evidenced by valve gaping and a swollen and nonresponsive foot. Copper was 5 to 15 times more toxic than Zn, with 48-hr LC50 values ranging from 52 to 156 μg Cu/L, and ECS5O values ranging from 25 to 115 μg Cu/L for juveniles of A. pectorosa. Copper appeared to exert a different toxic mode of action, as evidenced by closed valves and reduced siphoning. In general, sensitivities of early life stages of mussels to Zn and Cu increased with higher temperature, soft water, and length of exposure. At certain concentrations, Zn seemingly had an antagonistic effect (less than additive) when mixed with Cu. This effect was evidenced by reduced mortality of juveniles in Cu solutions when Zn was added at concentrations of about 400 to 800 μg/L. However, this antagonistic effect was not reflected in the percent of juveniles affected, which increased continuously with increasing metal concentrations. Glass beads were found unsuitable as a control substratum for use in sediment testing with juvenile mussels. Results of sediment tests indicated that sediment in some areas of the Powell River may be toxic to juvenile mussels, and that toxicity may be linked to water quality. After 10 days, survival of juveniles in sediment collected downstream of a coal processing plant was significantly lower than survival in sediment upstream of the plant (p = 0.01). Further, survival in sediments with dechlorinated tap water was significantly higher than survival in sediment with river water (p = 0.0002). After 20 and 30 days, survival was similar among sites and water types. High metal concentrations in the river water appeared to contribute to toxicity, because juveniles in tap water displayed consistently better growth, and initially better survival than juveniles in river water and sediment. This toxicity was not apparent in sediments collected from the same sites less than two months later, suggesting the character of the sediments may change as new suspended sediment is deposited. The USEPA water quality criteria for Zn (adjusting for water hardness) are 174 μg/L (acute) and 158 μg/L (chronic), whereas copper criteria are set at 28 μg/L (acute) and 18 μg/L (chronic). Powell River water samples collected during 1991 contained concentrations of Zn and Cu exceeding these criteria, as well as concentrations shown to have adverse effects on mussel populations. Results suggest that some metals are introduced into the river system in runoff, whereas Cu is being introduced as an episodic event. Intensive monitoring of water quality is needed to identify specific sources of metal pollution. If levels of heavy metal concentrations remain high, then the declining mussel populations of the Powell River will not recover, and endangered species may be extirpated from Virginia. / Master of Science

The overall objective is to improve the one-dimensional numerical prediction of the fine and non-cohesive bed material load in alluvial rivers, especially during high intensity episodes during which sediment beds are strongly remobilized. For this reason, we attempt to reduce the major inaccuracy sources coming from the alluvial resistance and bed material load relations needed to close the mathematical system. Through a shared parameter called the control factor m, the interactions occurring in alluvial rivers are incorporated more deeply into the mathematical model and more particularly into the closure laws: bed material load (SVRD, Suction-Vortex Resuspension Dynamics) and the energy slope (Verbanck et al. 2007). The control factor m is assumedly related to the Rossiter resonance modes of the separated flow downstream the bed form crest. <p><p>To further improve the representation of the flow-sediment-morphology interactions, a fully coupled model approach has been naturally chosen. In this work the terminology fully coupled means that the three equations forming the system are solved synchronously and that the terms often neglected by more traditional decoupled models are kept. <p><p>The feasibility of the new closure methodology has been drawn up by reproducing numerically the silt-flushing experiment conducted by the Yellow River Conservancy Commission (Y.R.C.C.) in the Lower Yellow River (LYR) in Northern China. The objective of the silt flushing experiment is to reverse the aggradation trend of the Lower Yellow River which, in the last decades, has become a perched river. The numerical simulation specifically reproduces the silt-flush effects in a reach of LYR located in the meandering part of the river. This reach (around 100 km) is delimited by Aishan and Luokou hydrometric stations.<p><p>Since the SVRD formulation has been developed from flume observations, the law has first been confronted to river datasets. The confrontation has revealed that the SVRD law becomes less suitable for fine sediment fluxes (ratio of water depth over median particle size > 5000). Therefore, a modified equation SVRD-2 has been built to enlarge the validity range.<p><p>The suitability of the SVRD-2 equation to predict fine sediment fluxes has been tested on data available from several hydrometric stations located in the meandering reach of the LYR: historical observations and measures collected during the flushes. The SVRD-2 has also been compared with relations specifically calibrated for this configuration. The comparison has pointed out that the performance of the two formulas is similar, which is encouraging for the SVRD-2 approach as it has not been calibrated on those data. <p><p>The closed equation system has been written on its quasi-linear form and is solved by a Finite Volume Method combined with a linearized Riemann algorithm. The numerical model has been checked up on two test cases: deposition upstream of a dam and the aggradation experiment conducted by Soni 1975. <p><p>As it is not yet possible to predict dynamically the value of the control factor m, a possible solution would be to extract its value from the measured data at the inlet cross section. Unfortunately, the necessary data are not measured locally. Moreover, a uniform value of the control factor m may not suffice to reproduce the flow along the whole reach. Therefore, it has been proposed to work temporarily in the reverse way. <p><p>From the comparison between the numerical results and the experimental data, a time evolution of the control factor m has effectively been extracted and it has been shown that it varies along the reach. At Aishan, the evolution of the control factor m corresponds to the evolution expected from the data analysis previously conducted on other data sets: the value of the control factor m decreases during the flush as it tries to reach the optimal value m=1. The time evolution at Luokou behaves differently to the one at Aishan, but remains in agreement with m evolution patterns observed historically for the river section flowing round Jinan City walls. For Luokou, the highlighted differences may come from three dimensional effects coming from the meander bend upstream the station.<p><p>Generally, the results obtained for the hydraulics, the sediment transport and bed adaptation are encouraging but still need improvements and additional feeding from the experimental data. The results for the concentration and therefore the bed elevation are very sensitive to the value of the control factor m as it influences most of the terms of the bed material load equation (SVRD-2). <p><p>The major remaining difficulties are, firstly, to deal with the rapid transients for which the model is less suitable and, secondly, to improve the prediction of the value of control factor m. Before paying more attention into the transients, enhancements concerning the flow along the reach (initial condition and discharge rates during the first days of the flush) must be conducted in priority. Indeed as the prediction of the bed or the cross section evolutions depend directly on the quality of the prediction of the sediment concentration and the hydraulics, one should first improve these aspects. To perform this study, more information about the water levels or sediment concentrations is necessary at some intermediate stations. One solution is to lengthen the studied reach, upstream to Sunkou and downstream to Lijin, totaling a river length of 456 Km.<p><p>A more entire signal of the energy slopes and the associated bed configurations at different stations would enlighten how the control factor m evolves along the reach during the silt-flush events. <p><p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

RésuméEn raison des spécificités relatives à la formulation des bétons autoplaçants (BAP) et en particulier ceux concernant leur volume élevé en pâte et la présence d'ajouts et substituts minéraux en grande quantité, leur comportement à l'état frais et à l'état durci ainsi que leur durabilité sont fortement influencés par ces deux paramètres.Certains sédiments traités acquièrent des propriétés pouzzolaniques et peuvent être utilisés en tant qu'ajouts ou substituts au ciment. Ceci peut faire de la technologie des bétons une voie privilégiée pour leur valorisation.La présente étude vise à apporter une contribution à la valorisation de la vase traitée du barrage de Chorfa et de Fergoug, (situé à l'ouest algérien) en tant que substitut minéral partiel au ciment CPA CEMI 42.5 dans la composition des mortiers et des bétons autoplaçants. Il s'agit de comparer l'influence de l'incorporation de cette vase calcinée à celle de la pouzzolane naturelle de Béni-Saf (situé, également à l'ouest algérien) dans les BAP sur leurs caractéristiques physico-mécaniques et sur leur durabilité à court, moyen et long terme.L'étude est menée sur quatre BAP, le premier à base de 20 % de pouzzolane naturelle de Béni-Saf (BAP-PZ), le deuxième et le troisième incorporant 20 % de la vase calcinée issue des sédiments de dragage du barrage de Fergoug (BAP-VF) et de celui de Chorfa (BAP-VC) et enfin un BAP témoin sans ajouts pour le besoin de comparaison.Outre l'intérêt économique que présentent les BAP à base de la vase calcinée, notre étude a montré que ces derniers représentent des performances très comparables à celles obtenues sur des BAP à base de pouzzolane naturelle (BAP-PZ).En effet, Concernant les résistances à la compression, notre étude indiquent que les BAP à base de vase ((BAP-VC) et (BAP-VF)) présentent les meilleurs résultats notamment à long terme.Les résultats des essais de l'attaque acide (HCl et H2SO4), l'attaque sulfatique (Na2SO4 et MgSO4) et de carbonatation accélérée, montrent que la vase calcinée a une influence sensiblement meilleure que celle de la pouzzolane sur les propriétés physico-mécaniques et la durabilité des bétons dans lesquels elle est incorporée.Mots clés : Barrage de Chorfa - Barrage de Fergoug –Vase calcinée – pouzzolane – BAP à base de vase – BAP à base de pouzzolane – Résistances mécaniques –Durabilité. / AbstractBecause of the specificities of self-compacting concrete (SCC), especially regarding their high volume paste content and the presence of large amounts of mineral admixtures and substitutes, the behavior in fresh and hardened state and the durability of these concretes are strongly influenced by these two parameters.Some treated sediments acquire pozzolanic properties and can be used as additions orsubstitutes to the cement. This possibility makes of concrete technology a privileged way of enhancement.The present study aims to contribute to the enhancement of the treated mud of Chorfa and Fergoug dam (situated in west of Algeria) as a mineral partial substitute for CPA CEMI 42.5 cement in the composition of an economic and preferment mortars and self-compacting concretes. The aim is to compare the influence of the incorporation of this calcined mud to the natural pozzolana of Beni Saf (situated, also in west of Algeria) in (SCC) on their physical, mechanical behavior and their durability of these concretes in short, medium and long term.The study was conducted on four SCCs, the first based on 20% natural pozzolana Beni Saf (SCC-PZ), the second based on 20% of the calcined mud of Fergoug dam (SCC-VF) and of Chorfa dam (SCC-VC) and a control SCC without additions to the need for comparison .Apart from the economic interest of the SCCs based on calcined mud, our study showed that these concretes have comparable performances to that obtained on SCC based on natural pozzolana (SCC-PZ).In fact, concerning compressive strengths, our study indicate that the SCC with calcined mud ((SCC-VC) and (SCC-VF)) present the best results especially at long termThe results of the different following tests: the acid attack (HCl and H2SO4), carbonation and sulphate attack (Na2SO4 and MgSO4) show that the calcined mud has an influence roughly better than the natural pozzolana on the physic - mechanical behavior and durability of the SCC which it is incorporated.Key words: Dam of Chorfa – Dam of Fergoug – Calcined mud – Pozzolana – SCCcontaining mud - SCC containing pozzolana – Mechanical strength –Durability.

Traditionally, flexible pavement design relies on past experience and semi-empirical methods developed through a combination of element testing and modelling. Element testing in this area especially, has centred on the performance of clean sands. This is in conflict with actual practice where a wide range of fines and soil gradations could be present in a real-world project. This research investigates the characteristics of natural sands and examines the influence of these marginal materials in pavement design using element testing and controlled modelling of an actual flexible pavement system. The element tests concentrated on separate, natural soils sourced from Kazakhstan which had similar mineralogy, but varying amounts of fines. One of the key parameters examined was equivalent void ratio and its efficiency to account for the behaviour change in granular materials which comes from increased fines content. Starting with monotonic triaxial results combined with strength-dilatancy methods it was shown that prediction of shear strength in a silty-sand could be improved by 13%. Incorporating this finding into repeat load triaxial tests, the transitions between elastic, plastic, and ratcheting failure behaviours (i.e. shakedown boundaries), commonly used to help predict the lifespan of a flexible pavement, were examined. It was seen that cycling a silty-sand, the stress path and yield surface could change depending on the fines content. The Cambridge Airfield Pavement Tester (APT) was designed and constructed to measure permanent subgrade deformation resulting from various surface loads. The number of input variables required to design flexible pavements is one of the most frequently stated problems in the field; variation of aircraft types, environmental conditions, and materials makes mechanistic design of the soil foundation problematic. Accordingly physical pavement modelling continues to be the only experimental method that allows input parameters and material characteristics to be examined simultaneously. Digital image correlation (DIC) was incorporated into the system; the first time this technology has been used in flexible pavement research. A Null Pressure System was also installed to measure soil stress distributions. It was observed that the critical failure mechanisms for thin and thick surficial layers are different, resulting in changes in the rates of surface rutting. Finally, by combining element and APT results, knowledge of the causal relationships between subsurface deformation and failure mechanisms in flexible pavement were advanced. In-situ soils, which are frequently incorporated into subgrade designs, were found to have a substantial role in the serviceability of the pavement. Correlations between element tests and APT results highlighted the complicated loading and boundary conditions present in a pavement.