Browsing by Subject "Erosion"
Now showing 1 - 14 of 14
Results Per Page
Sort Options
Item 2008 Midwest Levee Failure: Erosion Studies(2011-02-22) Bernhardt, Michelle LeeThe United States contains an estimated 100,000 miles (160000 km) of levees in which erosion related issues are the top priorities. Proper documentation of overtopping induced erosion is a complicated issue involving the collection and analysis of timesensitive field data and personal observations. This thesis is a study of the performance of the Midwest Levee system during the 2008 flooding events. The goal of the Midwest Levee investigation was to gather and analyze perishable data in an effort to provide a comprehensive overview at each breach location. To predict how a site will perform during a particular flood event, there are three main inputs: the flood conditions, the site conditions, and the soil properties. Site geometry and imperfections can greatly affect the performance of a levee system. Any low spots or potential seepage paths can concentrate the flow and be detrimental to the levee. The vegetative cover is the single most important condition at a site. As seen in the Brevator case, vegetative armor can prevent failure of a levee comprised of less resistant soils subjected to long periods of overtopping. Recommended grasses include: Switchgrass, Smooth Brome, Reed Canarygrass, and Tall Fescue. It is also recommended that grasses are kept at least 0.5 m tall during the flood season and to limit the presence of trees to 10 m beyond the levee toe. The erosion resistance of the materials comprising the levee is also important. From the correlations in this study, it was determined that erodibility is influenced by grain size, relative compaction, clay content, and activity. Devices like the Torvane and Pocket Erodometer can also be used to get a quick field estimate of erosion. While these correlations and field devices give insight into an erodibility value, they are no substitute for site specific analysis with laboratory equipment such as the Erosion Function Apparatus. Soil behavior is highly nonlinear and the entire erosion function is needed to get an accurate measure of the erodibility of a soil. By combining these properties in an erosion matrix, a prediction of whether a site will withstand a given flood event can be made.Item Degradation of pedogenic calcretes in West Texas(Texas Tech University, 2003-08) Hirmas, Daniel RNot availableItem Experimental Study of Multiphase Pump Wear(2014-08-06) Steck, Daniel D'AndreaThe goal of this research is to better understand upstream Oil & Gas Electric Submersible Pump (ESP) reliability issues. The objective of this research is to determine how Liquid-Gas-Particulate (LGP) turbine pump wear differs from Liquid-Particulate (LP) turbine pump wear. This objective is novel because little is known about LGP wear, yet such wear is common in ESPs. To accomplish the research objective, an experimental study of a gas handling ESP was conducted. Tests of two Baker Hughes 1025 MVP G400 Severe Duty turbine pumps were conducted with water, air, and sand. One pump was tested with a Gas Volume Fraction (GVF) of 20% while the other was tested with a GVF of 0%. It was found that particulates migrate radially outward through the pump and cause diffuser sidewall wear to increase through the pump. It was also found that various impeller flow path areas experience more LGP wear than LP wear. In general, pump wear progress faster for LGP wear than for LP wear. It is believed that this is caused primarily by the thinning effect that gas can have on a fluid?s viscosity.Item Experimental Testing of an Electrical Submersible Pump Undergoing Abrasive Slurry Erosion(2013-04-01) Saleh, Ramy Moaness MThe Electrical Submersible Pump (ESP) manufactured by Baker Hughes, model no. WJE-1000 is designed for wells that are expected to have a high content of abrasive solids. It is a mixed flow, tandem compression type pump. Although the erosion of the pump diffuser and impeller stages are significant, the ESP study shows that the most sever failure is due to components that affect the pump?s rotor dynamics such as radial bearings and impeller seals when eroded with 100 mesh sand. Erosion of these seals will result in an internal leakage that can significantly affect stage pressure rise, efficiency, power consumption, vibration, pump life and running cost. The erosion study utilizing 100 mesh fracture sand at 0.2% concentration, with the pump operating at 3600 RPM, 40 PSI intake pressure, 1150 GPM for over 117 hours comparisons are made to the pump?s baseline performance. Measurements of the rotor bearings, impeller seals and their corresponding stators showed that the wear patterns generally increase with time and differ by location. Stage 1 bearings and seals suffered the least amount of erosion and stage 3 rotor components suffered the most erosion. The maximum change in stage 3 bearing clearances was 223% and the maximum change in stage 3 impeller seal clearances was 300%. Performance wise the total pump efficiency dropped by 6.77%, the total pressure rise dropped by 6.3%, the pump?s best efficiency point decreased by 0.78%, and the power consumption increased by 0.49%. Pump vibration patterns also changed with time and by location. The maximum shaft orbit diameter was at stage 3 and it grew 643% in diameter after 117 hours of erosion. The waterfall plots of the pump?s ramp up changed significantly with time. After 117 hours at 3600 RPM, sub-synchronous oscillations at 67% of the synchronous speed dominated the amplitude peaks showing that the rotor vibration locked with the rotor?s first natural frequency at around 2500 RPM. After 117 hours, another sub-synchronous started showing a peak at the rotor?s second natural frequency at 1500 RPM.Item Modeling and Simulation of Solid Particle Erosion of Protective Films(2011-02-22) Banerjee, SouravAmong many useful properties of elastomers, one is their ability to absorb energy by deforming to large strains without fracturing. This property combined with their good adhesion to substrates makes them suited as adhesive films and coatings for protection against impact damage. An example of practical significance is the erosion of helicopter rotor blades where the protection of leading edge is often achieved by mounting a film or applying a coat of polyurethane. Although this is a workable solution, there is currently little knowledge as to the durability of this elastomeric film/coat under impact of hard and angular particles such as sand. A deformation and failure analysis that deals with the angularity of the erodents and captures the local mechanisms responsible for erosion damage in elastomers is the sine qua non. The present endeavor tries to address these issues by considering a polyurethane layer on a quasi-rigid substrate, impacted by hard particles at velocities and angles of attack given by pre-specified distributions. A novel method is devised to address the angularity issue. A series of finite-element calculations are performed on the coating layer-substrate systems subjected to different velocities, incidence and angularity of the impacting erodents. An elasto-plastic material constitution with isotropic hardening is employed in the simulations and material parameters representative of polyurethane are used for the coat. Initial parametric deformation analyses provided an adequate qualitative estimate of erosion parameters. Incorporation of a stress based fracture criterion enabled a quantitative measure of material removal due to erosion to be achieved. The simulation results show good match with experimental trends of target mass loss as obtained under normal and inclined loadings with angular erodents. The current simulation framework has sufficient capability and versatility to incorporate more enriched polymer-models and advanced fracture criteria in the future, thereby allowing parametric studies toward selection of materials and coat-layer thicknesses thus predicting the erosion mass loss as accurately as measured by experiments.Item Modeling the Effects of Low Impact Development Practices on Streams at the Watershed Scale(2014-04-28) Shannak, Sa'D AUrban growth contributes to increasing storm water runoff which in turn causes an increase in the frequency and severity of flooding. Moreover, increased storm water runoff contributes to changing the character and volume of energy inputs to the stream. Traditionally, storm water management controls such as detention pond had been extensively studied and evaluated with respect to reducing and controlling peak flows. Nonpoint source pollutants due to urbanization and expanding of agricultural fields have become a big burden on municipalities and states. Low Impact Development practices were developed to negate the negative impacts of urbanization on water resources by reducing the runoff volume and peak flows as well as improving outflow water quality. Though these practices have the capability of reducing runoff volumes and enhancing outflow water quality, they can be costly. Therefore, understanding the impact of installing LID practices on a watershed scale is becoming increasingly important. In this study, field experiment and model study were applied to evaluate the effectiveness of LID practices on a watershed scale in the Blunn Creek Watershed located in Austin, Texas. The three LID practices which were evaluated in this study are permeable pavements, a bioretention area, and a detention pond. The main objective of this study was to investigate the influences of these practices at a watershed scale on: potential reduction on channel bank erosion, potential reduction on flood, and potential impact on aquatic life. This study was one of very few studies that take place in the Blackland clay soil in Texas. A combination of different levels of LID practices such as permeable pavement and bioretention area resulted with achieving the main goal of this study of reducing stream bank erosion, bankfull exceedance, and maintaining acceptable flows for the integrity of aquatic life habitat. All LID practices have shown significant difference with respect to a control treatment at 95% confidence ratio. Performance of the modeled LID practices was validated by showing acceptable agreement in the percentage of reductions in total runoff between field experiments and model data.Item Off-Road Vehicle Impact on Sediment Displacement and Disruption at Assateague Island National Seashore, Maryland(2012-08-15) Labude, BrianThe National Park Service (NPS) monitors off-road vehicle (ORV) use in National Seashores across the United States. The sediment disturbance that is caused by ORVs is believed to have a large impact on erosion (by wind or waves), which there by affects the morphology of the foredunes. With greater knowledge of ORV impacts, the NPS can better manage ORV use and minimize anthropogenic affects to the coastal environment. There remains considerable uncertainty about the disturbance and its larger-scale impact. This study quantifies the sediment disturbance made by tire tracks, as well as the tire track form, width, depth, and evolution with relation to the number of vehicle passes and location on the beach at Assateague Island National Seashore (ASIS), Maryland. To measure ORV impact, ground-based LiDAR was used to collect detailed profiles across a three by three meter test plot at each site. Based on the quantification of the displaced sediment and redistribution of that sediment from the tracks, a recommendation to the NPS can be made as to where along the beach traffic should be limited to, in order to minimize impact to the physical environment at ASIS. Tire tracks were found to widen after the first pass, as a result of the imperfections of driving. Compaction of the sediment in the center of the tire track accounts for only a minimal amount of the sediment lost from the tire tracks. Sediment removal accounted for greater than 75% of the sediment lost from the tire tracks at all sites. It was concluded that sediment removal is the most dominant factor in the creation and evolution of a tire track. The width, depth, and evolution of a tire track were also found to be controlled by the imperfections of driving. Despite the amount of sediment disturbance, it is found that there is no net downslope displacement of sediment. This conclusion counters previous ORV impact studies and suggests that ORVs are not directly responsible for beach erosion. It is also recommended that to minimize the impact of OVRs on the beach at ASIS, the NPS should limit driving to the backshore.Item A predictive model for sand production in poorly consolidated sands(2010-12) Kim, Sung Hyun, 1983-; Sharma, Mukul M.; Prodanovic, MasaThis thesis presents a model for the process of sand production that allows us to predict the stability of wellbores and perforation tunnels as well as mass of sand produced. Past analytical, numerical, and empirical models on material failure and erosion mechanisms were analyzed. The sand production model incorporates shear and tensile failure mechanisms. A criterion for sand erosion in failed sand was proposed based on a force balance calculation on the sand face. It is shown that failure, post failure sand mechanics and flow-dominated erosion mechanisms are important in the sand production process. The model has a small number of required input parameters that can be directly measured in the lab and does not require the use of empirical correlations for determining sand erosion. The model was implemented in a numerical simulator. Three different experiments using different materials were simulated and the results were compared to test the model. The model-generated results successfully matched the sand production profiles in experiments. When the post-failure behavior of materials was well-known, the match between the simulation and experiment was excellent. Sensitivity studies on the effect of mechanical stresses, flow rates, cohesion, and permeability show qualitative agreement with experimental observations. In addition, the effect of two-phase flow was presented to emphasize the importance of the water-weakening of the sand. These results show that catastrophic sand production can occur following water breakthrough. Finally the impact of increasing sand cohesion by the use of sand consolidation chemicals was shown to be an effective strategy for preventing sand production.Item Soil-geomorphic relationships in the ancient Lake Lomax Basin, Southern High Plains(Texas Tech University, 1999-08) Cano-Garcia, Miguel A.The Lake Lomax Basin is on the southern margin of the High Plains in West Texas. Evidence suggests that it has been formed by subsidence/erosion processes in very eariy Pleistocene time and subsequent wind deflation. This study was conducted to determine the relationships between geomorphic surfaces and soil parent materials inside and outside of the basin and to generate information useful for a planned soil survey update. A preliminary study was conducted inside, as well as outside, of the basin. Clay mineralogy and particle-size distribution (PSD) analyses were used to differentiate between Blackwater Draw Formation and Ogallala Formation sediments. In the basin area, soil profile morphology was described along a 25-km east-west transect across the basin and along a 23-km north-south transect in the basin. Clay mineralogy, particle-size distribution, and selected chemical analyses were carried out. Particle-size distribution statistical parameters such as mean grain size, standard deviation, and skewness were used as criteria to discriminate among the different parent materials in transect samples.Item The Role of Climate in the Deformation of a Fold and Thrust Belt(2012-02-14) Steen, Sean KristianTheory and experiment show that the rate and geographic distribution of erosion control the rate and pattern of deformation in collisional mountain belts. Enhanced erosion reduces the mass of material that must be moved up and over ramps and uplifted in large folds. In order to test this and related ideas in a natural example, we have compared modeled rainfall to measured thrust sheet displacement, geometry, and internal deformation in the Appalachian fold and thrust belt. We use mean annual precipitation from a global climate model (GCM) as a proxy for rate of erosion. Deformation measurements were made on a portfolio of regional cross sections from Alabama to New England. During the Carboniferous Allegheny orogeny the Southern Appalachians moved from -30 ? to 0? latitude whereas the Central and Northern Appalachians lay between -15? and 5? latitude. Mean annual precipitation determined from the GENESIS 2 GCM (Grossman, per. comm.) varied from tropical to arid conditions as the collision both moved north and grew in breadth and height. The Southern Appalachians, which experienced more net rainfall than other regions, generally show more displacement, deeper present day exhumation, and shallower ramps than regions to the north. The vicinity of the Pine Mountain thrust sheet in the Southern Appalachians experienced the most displacement (~1.5X the Central Appalachian average) and bulk shortening (~1.6X the Central Appalachians) and produced the most eroded material (~1.5X the Central Appalachians). The latitude of the Pine Mountain thrust sheet in the Southern Appalachians received ~20% more rainfall than the Central Appalachians. Although the number of regional detachments and lithologies change from Southern to Central and Northern Appalachians, the change in rainfall both regionally at any one time and as the collision progressed may explain part of the change in structural style from south to north.Item Three Phase Erosion Testing and Vibration Analysis of an Electrical Submersible Pump(2014-01-13) Zheng, DezhiElectrical Submersible Pump (ESP) has been recognized as an excellent artificial lifting method in industry due to its high liquid flow rate in both onshore and offshore applications. As oil exploration goes deep into water, ESP equipment is facing a crucial problem of slurry erosion which may affect life and cost significantly. The wear caused by slurry erosion may bring the issue such as unbalanced side loads, severe vibration and decreased pressure head. Eventually, this phenomenon will lead to a complete system failure. In present work, a systematic study on the erosion wear has been carried out in order to give better understanding. The WJE-1000 ESP pump manufactured by Baker Hughes has been employed in this study. During the whole procedure, 117 hours two-phase (water-sand) testing has been performed and is followed by 68 hours three-phase (watersand- air) testing. A combined analysis by combining components erosion wear measurement, pump performance testing and vibration signal process has clearly indicated the trend of erosion process on each component. Furthermore, the correlation between vibration signals collected by proximity probe and remote 3D accelerometer provided a future direction for monitoring inaccessible downhole equipment. Finally, the conclusion that air could further accelerate ESP erosion has been found by comparing the erosion rate and vibration signals in two-phase test and three-phase test.Item Tracking shoreline change using archaeology: A case study from Copano Bay, Texas(2008-05) Barrera, James E.; Houk, Brett A.This thesis focuses on the erosion of archaeological sites around the shores of Copano Bay. The research data for this project comes from three sites that are on the shore of Copano Bay: 41AS3, 41AS109, and 41RF18. The majority of the data was gathered from site 41RF18 during field work in 2005. A description of methods used in the fieldwork and of the findings is included. Annual rates of erosion and the amount of time these sites have before completely eroding into the bay is determined. The methods used to determine the rates of erosion are discussed and the historical data gathered through archival research is also presented. Finally, preservation efforts for archaeological sites around Copano Bay are proposed.Item Using GIS and the RUSLE model to create an index of potential soil erosion at the large basin scale and discussing the implications for water planning and land management in Morocco(2015-12) Clark, Madeline Lacy; Eaton, David J.; Hajji, MustaphaSevere erosion rates endanger the drinking water and agroforestry sectors in Morocco. To determine ways to improve erosion mitigation in Morocco, this study examined the political landscape underpinning research and policy implementation nation-wide. It also conducted a case study for erosion modeling in the most important river basin for drinking water in Morocco, the Bouregreg Basin. In this case study, 15 erosion scenarios were constructed in ArcMap according to the Revised Universal Soil Loss Equation (RUSLE), the most commonly used tool to predict erosion in Morocco, to determine the effect of variation in data inputs on the quantity and severity of sheet and rill erosion. Results indicate that average annual erosion rates in the Basin are minimal to moderate, with localized areas experiencing severe rates over 25 tons/hectares/year, indicating that channel and gully erosion rather than sheet or interill erosion dominate in the basin. Increased DEM resolution from 30 to 90 meters amplified predicted erosion rates by a factor of 10, and variation in precipitation between the highest and lowest agricultural years yielded a difference in maximum erosion rates of nearly 60,000 tons/hectares/year. These results indicate that the spatial resolution of datasets and variation in climatic factors produce substantial differences in model output and may bias policy-making in light of variation in data management practices and the potential effects of climate change. In order for Morocco to reach its goal of implementing Integrated Water Resource Management (IWRM), operators and researchers should collaborate at the basin level and establish best data management practices in the drinking water and agro-forestry sectors of Morocco. To achieve these changes, this study recommends that decision makers reexamine how they fund and support erosion research and mitigation, and that all stakeholders coordinate to both compile data to develop empirical and process-based erosion models fitted to Morocco and calibrate these models through investing in representative field studies.Item Variability in Long-Wave Runup as a Function of Nearshore Bathymetric Features(2011-08-08) Dunkin, Lauren M.Beaches and barrier islands are vulnerable to extreme storm events, such as hurricanes, that can cause severe erosion and overwash to the system. Having dunes and a wide beach in front of coastal infrastructure can provide protection during a storm, but the influence that nearshore bathymetric features have in protecting the beach and barrier island system is not completely understood. The spatial variation in nearshore features, such as sand bars and beach cusps, can alter nearshore hydrodynamics, including wave setup and runup. The influence of bathymetric features on long-wave runup can be used in evaluating the vulnerability of coastal regions to erosion and dune overtopping, evaluating the changing morphology, and implementing plans to protect infrastructure. In this thesis, long-wave runup variation due to changing bathymetric features as determined with the numerical model XBeach is quantified (eXtreme Beach behavior model). Wave heights are analyzed to determine the energy through the surfzone. XBeach assumes that coastal erosion at the land-sea interface is dominated by bound long-wave processes. Several hydrodynamic conditions are used to force the numerical model. The XBeach simulation results suggest that bathymetric irregularity induces significant changes in the extreme long-wave runup at the beach and the energy indicator through the surfzone.