Dissertations / Theses on the topic 'Uniform soil'
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Yassin, Hendro. "The behaviour of beams and slabs with soffit projections supported by uniform subgrades." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278708.
Full textRitthiruth, Pawin. "Flexural Behavior of Cold-Formed and Hot-Rolled Steel Sheet Piling Subjected to Simulated Soil Pressure." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/101845.
Full textMaster of Science
Sheet piling wall is an essential structure used during the excavation process. Sheet piling can be hot-rolled and cold-formed. Hot-rolled sheet piling has long-been believed to have a better bending performance based on a test conducted by Hartman Engineering twenty years ago. However, cold-formed steel can have similar strength to hot-rolled steel. This experimental program studied the bending behavior of hot-rolled and cold-formed steel sheet pilings. This program quantified the influence of lateral loading from soil pressure on the moment capacity of the sheet piling. Four cross-sections with two pairs of equivalent bending properties were investigated. Sheet-piling specimens were set up as beam members and subjected to simulated soil pressure from an air bladder. The span lengths of the specimens were varied, while the loading area remains unchanged to examine the effect of different amounts of load. Lateral bracings were provided at discrete locations to establish a sheet piling wall behavior and allow local deflection of the cross-section. Load-pressure, load-deflection, load-strain, and moment-deflection responses were plotted to demonstrate the behavior of each specimen. The moment-deflection curves were then normalized to the corresponding material property of each specimen to make a meaningful comparison between different specimens. The results indicate that lateral loading of the soil pressure influences the bending capacity of the sheet pilings. The longer span length has less amount of transverse strains, resulting in a higher bending capacity. The hot-rolled sheet pilings have better bending performance also because of less transverse strains.
Hossain, Muhammad Shazzad. "Investigation of Soil Failure Mechanisms during Spudcan Foundation Installation." Curtin University of Technology, Department of Civil Engineering, 2004. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=15369.
Full textEventually, the spudcan becomes fully embedded and the soil flow mechanism reaches a fully localised failure mechanism with deep embedment. The lateral extent of visible distortion due to soil flow is confined well within 1.5-1.6 D (D: spudcan diameter). From both centrifuge and numerical investigations, it is found that in uniform clay, it is inevitable to form a cavity above the spudcan foundation. Thus, the stable cavity depth and soil back flow mechanisms are studied. It is clear that the back flow is caused by a Flow Failure, where it is due to the downward penetration of the spudcan. This is contrary to the Wall Failure that is the mechanism recommended by the current offshore design guidelines to estimate the stable cavity depth. In wall failure, the soil back flow is due to the cavity wall too high to stand. The stable cavity depth is estimated up to 4 times higher by the wall failure mechanism than the one by the flow failure. This explains that the wall failure is never observed in model test. Therefore, a new design chart with design formula is developed for design engineers in the stable cavity depth calculation. The spudcan bearing response is strongly correspondent with the variation of soil failure mechanisms during penetration. At the initial stage of the penetration, the spudcan bearing capacity increases with penetration, which is due to the increase of overburden pressure from cavity formation. At the second stage of the penetration, soil back flow embeds the spudcan, and the spudcan bearing capacity is increasing as the soil flow mechanism transits from its shallow failure mechanism to its deep failure mechanism.
At the final stage of the penetration, the spudcan bearing capacity reaches its ultimate value, where the deep/localised failure mechanism remains. A rough spudcan shows 14 % higher bearing capacity than a smooth spudcan. And a flat-plate shows 8 % higher capacity than a spudcan with a same surface roughness. The ultimate bearing capacity factor N, = 10.5 in uniform soil is recommended as a conservative value when the deep failure mechanism is reached. A correspondent N, = 10.1 in NC clay is suggested for a deeply embedded spudcan.
Thabang, Sebuki Minah. "Assessment on infield spacial variability of nutrients in a uniformly managed corn (Zea Mays L.) field." Thesis, University of Limpopo, 2011. http://hdl.handle.net/10386/501.
Full textThe impact of agricultural chemicals on the environment has come under close scrutiny in the country of South Africa, for that reason, we are investigating alternative and appropriate methods for nutrients management. The objective of the study was to assess infield spatial variability of soil nutrients in a uniformly managed corn field, and (ii) to recommend method that can potentially help corn (Zea mays L.) producers in Limpopo Province to enhance grain yield with optimal utilization of resources. The study was conducted at Syferkuil agricultural experimental farm (23o50’ S; 29 o40’ E) of the University of Limpopo, in the northern semi-arid region of South Africa. Prior to planting of corn on this uniformly managed 7 ha portion of a 1 705 ha farm, the field was mapped with Ag132 Trimble differentially corrected global positioning system (DGPS) equipped with Field Rover II® GIS mapping software. Land suitability assessment for corn was conducted before planting and the field was classified for suitability as S1 based on FAO guidelines for irrigated agriculture and South African Binomial System of Soil classification. Soils and corn leaf sample parameters, including N were collected and measured from geo-referenced locations on a 40 x 40 m grid. Nutrient distribution spatial maps were produced with Surfer software 8.0. There was a significant variability (P≤0.05) of soil nutrients and pH across the corn field. Corn grain yield ranged from 2.7 to 6.3 Mg ha-1. For a land suitability class of S1 under linear irrigation in a semi-arid environment, these grain yields were considered lower. This lower grain yields can be linked to variability of soil nutrients, and pH because the field was classified suitable according to FAO guidelines. This field, with its significant variability of nutrients and pH that resulted in lower grain yields, is potentially a good field for precision agriculture IX methods of nutrient management such site-specific management zones for environmental quality and economic efficiency. Keywords: Maize, Small-scale farming, Soil nutrient management, and Spatial variability
Lima, Juliana Toledo. "Pontos polêmicos acerca do forrageamento de cupins subterrâneos (Isoptera: Rhinotermitidae) : consumo de alimentos similares, reutilização de iscas e tunelamento em solos não uniformes /." Rio Claro : [s.n.], 2010. http://hdl.handle.net/11449/106569.
Full textBanca: Fabiana Elaine Casarin dos Santos
Banca: Sulene Noriko Shima
Banca: Luiz Carlos Forti
Banca: Maria Santina de Castro Morini
Resumo: Coptotermes gestroi e Heterotermes tenuis são espécies de cupins pertencentes à família Rhinotermitidae consideradas importantes pragas urbanas no Brasil, sendo que a segunda também é encontrada em ambientes agrícolas. No ambiente urbano, tais espécies são encontradas consumindo várias fontes celulósicas, algumas até aparentemente similares. O processo de forrageamento dos cupins subterrâneos é dinâmico e muda ao longo do tempo. Contudo, devido aos seus hábitos crípticos, existem alguns pontos polêmicos que precisam ser esclarecidos, principalmente visando melhorar e embasar as novas estratégias de manejo, tais como a tecnologia de isca. Em vista do exposto, a presente pesquisa propôs analisar e comparar, por meio de bioensaios, as respostas comportamentais de C. gestroi e H. tenuis considerando diferentes formas de apresentação do alimento e frente a recursos alimentares equivalentes. Uma vez que uma colônia pode utilizar várias fontes alimentares, também foi observado o comportamento de busca por novos alimentos, verificando o forrageamento desses insetos frente a recursos alimentares previamente visitados por outros cupins. Para esses bioensaios foram utilizados diferentes tipos de arenas experimentais compostas por câmaras "ninho" e câmaras alimentares. Adicionalmente, foi observado o comportamento de tunelamento dos forrageiros em solos heterogêneos, acrescidos de pistas físicas, químicas e biológicas, simulando aqueles presentes em áreas urbanas. Para tanto, foram utilizadas arenas bidimensionais compostas por duas placas de vidro separadas por uma moldura, a qual delimitava a área de tunelamento disponível para os indivíduos. Todos os dados obtidos foram analisados gráfica e estatisticamente, sendo que o nível de significância (a) adotado foi igual a 0,05. De acordo com os resultados obtidos nos experimentos com diferentes formas de apresentação... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Coptotermes gestroi and Heterotermes tenuis, termites of the Rhinotermitidae family, are considered important urban pests in Brazil. The latter is also found in rural areas. In urban environments, these species consume many cellulose sources, some apparently similar. The foraging behavior of subterranean termites is dynamic and changes throughout time. However, due to their cryptic behavior, some questions still remain, especially regarding the construction of a framework and the improvement of new control strategies involving baits. The present study was aimed at analyzing and comparing the behavioral responses of C. gestroi and H. tenuis using bioassays involving different food presentations and equivalent food resources. Since a colony can feed on many food sources, the searching behavior of new food items was examined as well as foraging of food items previously visited by other termites. Bioassays consisted of different types of arenas with a "nest" and feeding chambers were carried out. Also, the tunneling behavior of foragers in heterogeneous soils and physical, chemical, and biological cues was examined, simulating those present in urban areas. Bioassyas consisted of two glass plates separated by a frame delimitating the tunneling area available for the termites were carried out. The results were analyzed and significance level was set at p = 0.05. Based on the results obtained in the experiments with different forms of presentation of the food item, both species had similar behavioral patterns, showing a bias toward food items completely buried in the substrate. Regarding the exploitation of equivalent food sources, no differences were observed between consumption and recruiting for the first food sources visited compared to other sources available. Thus, C. gestroi and H. tenuis did not concentrate their efforts in the consumption of the first food item found. In tenacity... (Complete abstract click electronic access below)
Doutor
Lissy, Anne-Sophie. "Imagerie quatitative non invasive et expérimentation pour l'intégration des phénomènes d'écoulement non uniforme dans les modèles de transfert de masse en milieux poreux hétérogènes : Application aux sols structurés." Thesis, Avignon, 2019. http://www.theses.fr/2019AVIG0709.
Full textPredicting the evolution of groundwater resource due to future climate change requires a better knowledge of water flows in soils which are highly complex porous medium. A lot of research has been conducted about soil water flow complexity over the last decades but predicting water flow in soils whatever soil texture, soil structure and rainfall intensities still remains a challenge. The objective of this work is to improve the modeling of water flow in structured soils by accounting to water flow from macropores to the soil matrix. We follow three successive steps : (i) to perform infiltration – drainage experiments on decimetric undisturbed soils columns under a medical tomograph to better observe flow phenomena within the soil macroporosity, (ii) to extract structural indicators from tomographic images, and study the macroporous soil structure, and (iii) to integrate structural indicators into a Darcy-Richards – KDW dual compartment flow model. Undisturbed soils studied are sampled from three different plots: (i) a clay soil worked in a field crop, (ii) a clay soil not worked in an orchard and (iii) a silt – sandy soil not worked and not cultivated. Three infiltration – drainage experiment are performed in a medical tomograph with fast image acquisition (~15 sec), 30 mm of water is supplied with a rainfall simulator and an intensity of 20 mm.h-1. Infiltration duration was of 90 min followed by 30 min of drainage. In total, the tomographic follow-up takes 120 min. Each experiment is done at three initial moisture conditions: (1) field capacity, (2) matrix potential at – 4 m, and (3) matrix potential at – 8 m. The initial structure observed before each infiltration shows that the soil macroporosity increases from 2 to 5% with the decrease of the initial water content. This increase is higher for the two clay soils compared to the silty – sandy soil. The hypothesis is that soil texture influences the evolution of the soil structure according to the matric water content. Thus, clay soils have the most variable soil structure over time, unlike silt – sandy soils which seem more structurally stable. Rapid movements of the soil structure during the infiltration and drainage phases was observed thanks to the time lapse tomographic monitoring. During water flow, soil macroporosity decreases between 7 to 30 % and increases again during drainage. The decrease of soil macroporosity during infiltration is more pronounced for the most saturated initial condition. The increase is less marked for the driest conditions. The hypothesis is that water flow along the macropores’ walls destabilizes causes an ‘over-swelling’ of the walls, which reverses during drainage. The study of overall indicators show that temporal monitoring of macropores density and their volumes makes it possible to discriminate specific texture and tillage behaviors different for the three soils. Models performed with the addition of profiled data measured on tomographic image in water flow model show that these measurements allow to reconstruct experimental data. Although the gap between modelling and observation for the driest experiments seems to indicate that it is necessary to continue the study of macropores – matrix exchanges in unsaturated conditions. This requires further study of the movements of the structure during wetting – drying cycles but also during the fast water flux transit
Lima, Juliana Toledo [UNESP]. "Pontos polêmicos acerca do forrageamento de cupins subterrâneos (Isoptera: Rhinotermitidae): consumo de alimentos similares, reutilização de iscas e tunelamento em solos não uniformes." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/106569.
Full textFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Coptotermes gestroi e Heterotermes tenuis são espécies de cupins pertencentes à família Rhinotermitidae consideradas importantes pragas urbanas no Brasil, sendo que a segunda também é encontrada em ambientes agrícolas. No ambiente urbano, tais espécies são encontradas consumindo várias fontes celulósicas, algumas até aparentemente similares. O processo de forrageamento dos cupins subterrâneos é dinâmico e muda ao longo do tempo. Contudo, devido aos seus hábitos crípticos, existem alguns pontos polêmicos que precisam ser esclarecidos, principalmente visando melhorar e embasar as novas estratégias de manejo, tais como a tecnologia de isca. Em vista do exposto, a presente pesquisa propôs analisar e comparar, por meio de bioensaios, as respostas comportamentais de C. gestroi e H. tenuis considerando diferentes formas de apresentação do alimento e frente a recursos alimentares equivalentes. Uma vez que uma colônia pode utilizar várias fontes alimentares, também foi observado o comportamento de busca por novos alimentos, verificando o forrageamento desses insetos frente a recursos alimentares previamente visitados por outros cupins. Para esses bioensaios foram utilizados diferentes tipos de arenas experimentais compostas por câmaras “ninho” e câmaras alimentares. Adicionalmente, foi observado o comportamento de tunelamento dos forrageiros em solos heterogêneos, acrescidos de pistas físicas, químicas e biológicas, simulando aqueles presentes em áreas urbanas. Para tanto, foram utilizadas arenas bidimensionais compostas por duas placas de vidro separadas por uma moldura, a qual delimitava a área de tunelamento disponível para os indivíduos. Todos os dados obtidos foram analisados gráfica e estatisticamente, sendo que o nível de significância (a) adotado foi igual a 0,05. De acordo com os resultados obtidos nos experimentos com diferentes formas de apresentação...
Coptotermes gestroi and Heterotermes tenuis, termites of the Rhinotermitidae family, are considered important urban pests in Brazil. The latter is also found in rural areas. In urban environments, these species consume many cellulose sources, some apparently similar. The foraging behavior of subterranean termites is dynamic and changes throughout time. However, due to their cryptic behavior, some questions still remain, especially regarding the construction of a framework and the improvement of new control strategies involving baits. The present study was aimed at analyzing and comparing the behavioral responses of C. gestroi and H. tenuis using bioassays involving different food presentations and equivalent food resources. Since a colony can feed on many food sources, the searching behavior of new food items was examined as well as foraging of food items previously visited by other termites. Bioassays consisted of different types of arenas with a “nest” and feeding chambers were carried out. Also, the tunneling behavior of foragers in heterogeneous soils and physical, chemical, and biological cues was examined, simulating those present in urban areas. Bioassyas consisted of two glass plates separated by a frame delimitating the tunneling area available for the termites were carried out. The results were analyzed and significance level was set at p = 0.05. Based on the results obtained in the experiments with different forms of presentation of the food item, both species had similar behavioral patterns, showing a bias toward food items completely buried in the substrate. Regarding the exploitation of equivalent food sources, no differences were observed between consumption and recruiting for the first food sources visited compared to other sources available. Thus, C. gestroi and H. tenuis did not concentrate their efforts in the consumption of the first food item found. In tenacity... (Complete abstract click electronic access below)
Štefaňák, Jan. "Statistická analýza kontrolních zkoušek horninových kotev." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-371785.
Full text"Development of Uniform Artificial Soil Deposition Techniques on Glass and Photovoltaic Coupons." Master's thesis, 2016. http://hdl.handle.net/2286/R.I.40263.
Full textDissertation/Thesis
Masters Thesis Mechanical Engineering 2016
Potsane, Moshe Moses. "Group invariant solutions for contaminant transport in saturated soils under radial uniform water flow background." Thesis, 2013. http://hdl.handle.net/10539/13004.
Full textThe transport of chemicals through soils to the groundwater or precipitation at the soils surfaces leads to degradation of the resources such as soil fertility, drinking water and so on. Serious consequences may be su ered in the long run. In this dissertation, we consider macroscopic deterministic models de- scribing contaminant transport in saturated soils under uniform radial water ow backgrounds. The arising convection-dispersion equation given in terms of the stream functions is analyzed using classical Lie point symmetries. A number of exotic Lie point symmetries are admitted. Group invariant solu- tions are classi ed according to the elements of the one-dimensional optimal systems. We analyze the group invariant solutions which satisfy some physical boundary conditions. The governing equation describing movements of contaminants under ra- dial water ow background may be given in conserved form. As such, the conserved form of the governing equation may be written as a system of rst order partial di erential equation referred to as an auxiliary system, by an in- troduction of the nonlocal variable. The resulting system of equations admits a number of (local) point symmetries which induce the nonlocal symmetries for the original governing equation. We construct classes of solutions using the admitted genuine nonlocal symmetries, which include the invariant solutions obtained via corresponding point symmetries of the governing equation.
Fu, Qingwei. "Interpretation of soil behavior from laboratory specimens subjected to non-uniform loading conditions /." 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3269895.
Full textSource: Dissertation Abstracts International, Volume: 68-07, Section: B, page: 4672. Adviser: Youssef M. A. Hashash. Includes supplementary digital materials. Includes bibliographical references (leaves 266-272) Available on microfilm from Pro Quest Information and Learning.
Chen, Yu-Wen, and 陳郁文. "The Effects of Geogrid Transverse Ribs on Pullout Behavior in Uniform Coarse Grain Soil." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/79414610942228439499.
Full textWang, Jyun-Yen, and 汪俊彥. "Experimental Study on Seepage Failure of Uniform and Gap-Graded Soils." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/9s722t.
Full text國立臺灣科技大學
營建工程系
100
Soil piping is a hydraulic and geotechnical phenomenon that soil hydraulic fails due to seepage. Soil piping can happen in geotechnical engineering and ecosystem. An upward seepage testing system is developed to study the seepage failure of soil. The testing system consists of a transparent acrylic permeameter, a constant head device and a data acquisition system. Using this test apparatus, a series of experiments on uniform sand and gap-graded sand are carried out to observe the process of seepage failure of specimen and to determine the critical hydraulic gradient. This study found the seepage failure mode is depended on the internal stability of soil which mainly depends on the grain size distribution and can be assessed using stable criteria. Test result shows seepage failure of uniform sand (internally sable soil) typically experiences an expansion of specimen thickness and the liquefaction of specimen, which is associated with the condition of effective stress equals zero. Seepage failure of gap-graded sand (internally unstable soil) is related to the internal erosion of fines which shows the finer particles in specimen will be vigorously eroded out with upward seepage flow, but the coarser particles remain comparatively stable. Further, the critical hydraulic gradients icr of soil obtained from test are compared with the predicted icr using theoretical equation proposed by Terzaghi. It is found the values of icr of uniform sand range from 0.89 to 1.21 which are close to the predicted icr. The values of icr of gap-graded sand range from 0.27 to 0.43 are far lower than the predicted icr. A database of icr of soil is compiled from this study and relevant literatures, and is used to compare different icr prediction methods and identify a best prediction method. Comparison result shows there is no a best methods can accurate predict the icr for all types of soils, but Terzaghi’s equation can predict the icr well of soil which satisfies the stable criterion proposed by Kenny and Lau (1985). Finally, this study is expected to provide the contribution in geotechnical engineering for a better understanding of seepage failure of soil and their critical hydraulic gradient.
Wan, Yongshan. "Soil erosion processes and sediment enrichment in a well-aggregated, uniformly-textured oxisol." Thesis, 1996. http://hdl.handle.net/10125/9276.
Full textChen, Wei-Meng, and 陳維孟. "Influence of Grain Shape And Cofficient of uniform on Liquefaction-related Behavior of Saturated Granular Soils." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/38mb7z.
Full text朝陽科技大學
營建工程系碩士班
91
Taiwan is located between of two of the world’s major tectonic plates. Earthquake occurred very often in this area and caused many disasters in the past. When a saturated sand deposit is subjected to ground vibrations, it tends to compact and decrease in volume. If drainage is inadequate, the tendency to decrease in volume results in an increase in pore water pressure. When pore water pressure built up is equal to or greater than the overburden pressure, the sand deposit becomes partially or completely liquefied. This phenomenon is called liquefaction, which is one of the reason that causes severe damages to the structures during major earthquakes in saturated sand deposits. The purpose of this research were to study the effect of grain shape and coefficient of uniform on liquefaction-related behavior of sandy soils using portable soil tank and shaking table. The Results of the study revealed that rounded-grained soils have the highest liquefaction potential while angular-grained soils are most unlikely to liquefy. In the other hand, the volume strain from liquefaction in rounded-grained soils is 2% more than angular-grained soils has. The Results of the study also indicate that the most liquefialble grain sizes are 0.05mm ~ 0.2mm for angular soils, 0.075mm ~ 0.2mm for sub-angular soils, 0.2mm ~ 0.6mm for plate-shape soils. Keyword:liquefaction、liquefaction potential、volume strain
Liou, Jong-Dar, and 劉仲達. "Synthesis of Uniform Silica Micro-nanospheres by Sol-Gel Method and Analysis of Their Physical Properties." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/8j66u6.
Full text國立交通大學
工學院半導體材料與製程設備學程
106
This research employs a chemical synthesis route to fabricate monosized silica microspheres by using a sol-gel method . This sol-gel approach is considered as the most economical way to produce silica micro spheres. Our process is based on a formula developed by W. Stöber, A. Fink, and E. Bohn (J. Colloid Interface Sci. 26, 62 (1968)), which used tetraethyl silicate (TEOS) as the precursor, ammonia (NH4OH) as the catalyst, and ethanol as the solvent. We adjust relevant parameters so that monosized microspheres could be successfully produced. In this work, we demostrate the formation of 284 nm silica microspheres with a standard deviation of 5 nm. Subsequently, physical characterization of the as-synthesized microspheres is conducted and discussed.