Rozprawy doktorskie: „Behavior of silty sand”

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Shi, Liangyu. "Influence of artificial weak cementation on loose silty sand behavior /". View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20SHI.

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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.
Includes bibliographical references (leaves 163-170). Also available in electronic version. Access restricted to campus users.

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Tedeschini, Lucia. "On the experimental behaviour of a silty sand and its modelling through Generalized Plasticity". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.

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La tesi contiene uno studio sperimentale sul comportamento di una sabbia limosa del sottosuolo della laguna veneta e propone un'interpretazione dei risultati sperimentali ottenuti alla luce dei presupposti teorici di un approccio costitutivo avanzato noto come "Plasticità Generalizzata". Il programma sperimentale è consistito nella realizzazione di prove edometriche e prove triassiali su campioni di sabbia provenienti dal sito di Treporti, situato in prossimità della bocca di Lido. La risposta sperimentale, in termini di modulo volumetrico, è stata messa a confronto con i risultati di alcuni studi di letteratura, con particolare riferimento a quelli condotti da Jefferies & Been (2000). La disponibilità di prove di compressione edometrica realizzate nella cella K0 e la conseguente possibilità di valutare il coefficiente di spinta a riposo ha permesso di interpretare le prove in termini di tensione media efficace p' e di verificare l'applicabilità al caso in esame degli approcci di letteratura disponibili, spesso sviluppati a partire da prove di compressione isotropa effettuate in cella triassiale. Il comportamento tenso-deformativo osservato è stato successivamente simulato con un modello costitutivo per sabbie sviluppato nell'ambito della Plasticità Generalizzata. In particolare sono state utilizzate tre diverse formulazioni, che costituiscono un avanzamento dell'iniziale modello costitutivo proposto da Pastor, Zienkiewicz e Chan (1990), basate sull'uso di un parametro di stato del materiale definito rispetto alle condizioni di Stato Critico. Dal confronto tra previsioni del modello e risposta sperimentale è stato possibile individuare la formulazione che meglio simula il comportamento meccanico osservato sia in compressione edometrica sia in prove di taglio ed è stato proposto un set di parametri costitutivi ritenuti rappresentativi del terreno studiato.

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Bowman, April Joy. "Performance of silty sands and their use in flexible airfield pavement design". Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/287462.

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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.

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Ajorloo, Ali Mohammad. "Characterization of the mechanical behavior of improved loose sand for application in soil-cement deep mixing". Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10044/document.

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Les technologies de mélange de sol en profondeur (« deep mixing ») pour le soutènement des excavations sont de plus en plus utilisées dans le monde. Le mélange de sol en profondeur devient une alternative plus économique aux systèmes traditionnels de soutènement pour les travaux d'excavation, pour la conception des fondations superficielles, l'analyse de la stabilité des talus et de la liquéfaction des sols. Ceci nécessite un développement plus poussé des modèles décrivant le comportement mécanique des sols ainsi améliorés, comme base pour accroitre la sécurité et diminuer les coûts économiques. Cette thèse est basée sur l'étude en laboratoire des caractéristiques de résistance au cisaillement d’un sable siliceux modifié avec du ciment de Portland, seul ou en combinaison avec des liants à réactions lentes (pouzzolaniques) comme des fumées de silice et de la chaux. Les effets de la cimentation sur la résistance, la rigidité et le comportement contractant-dilatant du sable cimenté sont étudiés au cours d’essais de compression simple, de traction, de cisaillement direct et de compression triaxiale drainée pour des éprouvettes maturées jusqu'à 180 jours. Plus précisément, les modes de rupture, les paramètres de résistance au cisaillement pour le sable lâche et dense, le module de cisaillement et les réponses volumétriques, l'état critique des sols cimentés sont décrits. En outre, cette étude vise à développer une formulation « Ready Mix », où le type de liant utilisé et le rapport eau/ciment ou eau/liant jouent un rôle fondamental dans l'évaluation de la résistance visée pour une utilisation en « deep mixing » de sols granulaires de type SM (resp SP) dans la classification LPC (resp USCS). Le comportement contrainte-déformation des sables cimentés est non linéaire avec une alternance contractance-dilatance. Une augmentation de l'angle de résistance au cisaillement et de la cohésion avec l'augmentation de la teneur en ciment a été observée de façon uniforme. Pour le sable sans ciment, la résistance au pic correspond au taux maximum d'expansion volumétrique, alors que pour le sable cimenté elle représente une condition où la sommation de toutes les composantes prend son intensité maximale. Finalement, la corrélation entre la résistance à la compression simple et l'indice lié à la réaction pouzzolaniques de la chaux et de la fumée de silice a été discutée
The use of deep soil mixing technology for excavation support is growing worldwide. As soil deep mixing becomes a more economical alternative to traditional support systems for excavation, shallow foundation design and analysis of slope stability and liquefaction of soil, the amelioration of models describing the mechanical behavior of improved soil is required, as a basis for cost-effectiveness and a safer design. This work features a laboratory study of shear strength of a loose silica sand modified with Portland cement only or in combination with high curing time binders (due to pozzolanic reactions) such as lime and silica fume. The effects of cementation on the stress–strain behavior, stiffness and strength of treated sand are investigated through unconfined compression tests, tensile strength tests, direct shear tests and drained triaxial compression tests, for curing times up to 180 days. More precisely, failure modes, shear strength parameters for loose and dense sand, volumetric responses and critical state of cemented sand are described. In addition, this study attempts to develop a « ready mix » design procedure, where the type of binder, water/cement or water/ binder ratios play a major part in the assessment of the targeted strength in deep soil mixing applications for loose granular soils (SP in the unified classification). The results show that the stress–strain behavior of cemented sands is nonlinear with contractive–dilative stages. The stress-strain response is strongly influenced by effective confining pressure and cement content. For uncemented sand, the peak strength occurs for a maximum rate of volumetric expansion, whereas for cemented sand it represents a condition where the summation of all components the maximum intensity become. Finally, the correlation of unconfined compression strength with the index of pozzolanic reaction of lime and silica fume is discussed

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Yusa, Muhamad. "Aging and creep of non-plastic silty sand". Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2015. http://hdl.handle.net/10092/10754.

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Soil aging refers to the increase in strength and stiffness that is exhibited over time after it is disturbed. It is common in granular soils, such as sands, occurring over periods from hours to years. There have been relatively numerous laboratory studies on sand aging phenomena. However the majority of these studies were conducted on relatively clean sand (fines content <5%) and were performed under isotropic condition. In nature, granular soils with fines content > 5% are not uncommon. This research is an attempt to gain further insight and understanding of mechanical aging on silty sand by conducting laboratory studies mostly under K0 condition, which better reflects the field condition, at both macro-scale (triaxial test) and micro-scale (fabric test). As many factors (e.g. plasticity of fines, fines content, grain size composition, angularity and shape) affect silty sand behaviour and not all those factors could be investigated during the study period, this study focused on mechanical aging of non-plastic silty sand with 15% fines content. Triaxial tests have been conducted in this study in order to observe creep behavior under different density, initial fabric, and consolidation stress paths (K0 and isotropic). The tests were conducted at low effective confining stress stresses i.e. ’3= 30 – 120 kPa as this is relevant to many geotechnical aging problems (e.g. time effects on freshly deposited or disturbed soils such as in the case of hydraulic fills, mine tailings, and post-liquefaction state of soil behaviour following earthquakes). Creep induced aging effects on undrained shear behaviour at small-strain (<0.1% of shear strain), were investigated, as this strain range is most common in geotechnical structures under gravity-induced working loads. Aging effects on one way cyclic behaviour were also studied. Some new key findings from these tests are as follows: (1) Creep following K0 consolidation indicated that the soil tends to expand radially over time, resulting in a tendency of increasing horizontal stress with time even at low stress. (2) Following K0 consolidation, density appears to have more significant effect on creep compared to initial shear stress ratio and mean effective stress; as demonstrated by loose samples (low stress ratio and mean effectives stress) which exhibited greater creep compared to those of dense sample (higher stress ratio and mean effective stress) (3) For loose soils, there is a trade-off between high confining stresses driving aging and collapsing pore space. Generally higher confining stress was found to increase creep tendency thus enhancing aging, however there was also found to be a certain confining pressure where the aging effects became less due to local structure collapse. (4) Initial fabric plays an important role on creep development, thus aging. For instance, dense dry pluviated samples developed larger axial strain over time but also gained less increase in stiffness compared to dense moist tamped samples. This suggests the importance of specimen preparation for laboratory testing that replicates the field scenarios e.g. natural deposition and associated fabric; (5) Dense K0 consolidated samples produce more increase in stiffness with time than corresponding isotropically consolidated samples. Hence, as the K0 condition generally reflects the level-ground free field stress condition better, it is important to test under K0 if the degree of stiffness gain is important; (6) The number of cycles to trigger cyclic softening and liquefaction for one way cyclic loading increases with the aging duration. In addition there is tendency that the aging effect is more pronounced at lower cyclic stress ratios. Fabric tests under K0 consolidation with similar variables as the triaxial tests were also performed. Some new insights and contributions have been obtained as follows: (1) Moist tamped samples, have particles that are more clustered together and structured than dry pluviated samples; (2) In terms of particle orientation, a change in the degree of orientation for both sand particles and ‘fines’ under constant loading was observed with time. The dominant (i.e. most) rotated particles (sand or “fines’) depends on the initial fabric and density; (3) Over time, under constant loading, growth of micro voids was observed for dense samples while those of loose samples contracted; (4) A new parameter, variance to mean void ratio of void distance, was introduced as a measure of the degree of interlocking during aging. The variance to mean ratio of void distance for moist tamped samples tends to decrease whereas those of dry pluviated samples tends to increase with time. An increase in variance and variance to mean ratio for dry pluviated samples indicates that particles are more clustered together with time; (5) Original work on spatial void distance for the numerical analysis of creep induced aging based on Kang et al. (2012) was conducted (note: the model’s boundary condition allows lateral expansion, which is not the same as the fabric tests conducted). The analysis showed that mean void size in dense soil tends to increase with time under constant load while for loose sample it tends to decrease. However the particles also clustered together more – increasing structure. (6) A microstructural study of “undisturbed samples”, obtained by gel-push sampling, of clean sand (fines content = 4%) and silty sand (fines content = 30%), was conducted to investigate anisotropy of natural fabric of granular soils. The results show that dry pluviation reflects the field condition more, in terms of natural deposition, than moist tamping. In addition, spatial void distance qualitatively indicated the undisturbed samples are relatively “very young”, even in terms of engineering time, as indicated by similar variance to mean ratio and kurtosis with those of 1 hour and 1 week reconstituted samples. This research has shown that there was a relation between changes in the microstructure over time and changes in macro mechanical properties of non-plastic silty sand. Further improvement in theoretical modeling (e.g. numerical modeling of creep on polydisperse granular material) and experimental aspects (e.g. examining different grain size composition and angularity, different fines content, the influence of the shape of sand and fines and use of the photo-elastic method) will allow a better understanding of the sand aging phenomenon in silty sand.

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Rahardjo, Paulus P. "Evaluation of liquefaction potential of silty sand based on Cone Penetration Test". Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/53844.

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Liquefaction ls a phenomenon where a saturated soil can temporarily lose its shear strength during an earthquake as a result of the development of excess pore pressures. For the past 25 years since Iiquefaction phenomenon was first explained, it was thought to be mainly a problem with clean sand, and most of the research has focused on these soils. However, as case history information has come to light, it has become apparent that silty sands are commonly involved, and in some cases even silts. This has generated a need for knowledge about the response of silty sands and silts under seismic loading. Related to this issue is the question of how best to determine the Iiquefaction resistance of these soils in a practical setting. This research has the objectives of providing an understanding of the behavior of saturated silty sands under seismic loading, and developing a rational basis for the use of the Cone Penetration Test (CPT) to predict Iiquefaction resistance in these materials. The study is primarily experimental, relying on laboratory and field testing and the use of a unique, large scale calibration chamber. The calibration chamber allows the field environment to be duplicated in the laboratory where conditions can be closely controlled and accurately defined. One of the first problems to be overcome in the research was to determine how to prepare specimens of silty sands that would reasonably duplicate field conditions in both the small scale of the conventional laboratory tests, and the large scale of the calibration chamber. Out of four different methods explored, consolidation from a slurry proved to be best. Two silty sands were located which had the desired characteristics for the study. Field work, involving both the Standard Penetration Test (SPT) and CPT was done as part of this investigation. The behavior of the silty sands were determined in the laboratory from monotonic and cyclic loading tests. The test results show that the effect of fines is to reduce the cone penetration resistance, but not to affect the liquefaction resistance. The steady state shear strength of the soils seems to be correlated to the cone tip resistance, however, this correlation shows a higher steady state shear strength than those back figured from case history data. The results were also used to define state parameters for both of the soils tested. The state parameter was found to be a reliable index to the liquefaction potential and further study in this area is recommended.
Ph. D.

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Valentine, Todd J. "Dynamic Testing of a Full-Scale Pile Cap with Dense Silty Sand Backfill". Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2021.pdf.

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Runnels, Immanuel Kaleoonalani. "Dynamic Full-Scale Testing of a Pile Cap with Loose Silty Sand Backfill". Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1854.pdf.

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Quimby, Michael James. "Liquefaction Mitigation in Silty Sands Using Stone Columns with Wick Drains". BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/2228.

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Stone column treatment is commonly used to mitigate liquefaction hazard in sandy soils. Research and experience indicate that this method is effective for clean sands but that it may not be effective for silts and sands with fines contents greater than 15-20%. An alternative to the stone column method involves supplementing stone column treatment with pre-fabricated vertical wick drains installed prior to the stone columns installation. Although this method is used in practice, there has not been a formal academic study of its effectiveness. This thesis evaluates seven different case histories where wick drains were used and one where wick drains were not used, for comparison purposes. The site locations varied as well as the soil properties and treatment plans. CPT testing was done at 3 sites and SPT testing was performed at the other 5 sites. CPT data were correlated to SPT data to facilitate comparisons. One of the case histories includes a unique study in which three different variations of the stone column treatment were applied at the same site, providing a direct comparison of the effectiveness of each method. A 26% area replacement ratio (Ar) with drains was determined to be more effective overall than a 26% Ar without drains and more effective in increasing low initial blow counts than the 34% Ar without drains. The areas with drains were more likely to exceed the minimum project criteria consistently throughout the site. Significant scatter were observed in the results and probable causes for the scatter are noted. Final blow count coefficients of variation ranged from 28% to 77%. Increased fines contents required increased Ar in order to maintain similar average final blow counts. Site improvements were evaluated separately and collectively. Individual site results were compared to clean sand curves developed by Baez (1995). Sites with average fines contents less than 20% which were improved using drains and an 11-15% Ar treatment were comparable to clean sand sites without drains and with 5-10% Ar. To achieve similar improvement at sites with 40-46% fines necessitated drains and Ar values of 23-26%. Design recommendations are provided.

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Hoang, Ngoc Lan. "Etudes des propriétés hydromécaniques d’un sable limoneux : de la saturation partielle à la saturation complète". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSET005/document.

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Cette thèse concerne la caractérisation expérimentale d’un sable limoneux provenant du barrage de Livet – Gavet (38) dans le cadre du projet ANR TerreDurable avec plusieurs objectifs : 1- Caractériser au travers d’essais de laboratoire le comportement hydromécanique d’un sable fin limoneux (sol A1 dans la classification GTR) en fonction de son état de saturation. Lors de cette étude, un accent particulier est porté sur la caractérisation de ce comportement dans le domaine proche de la saturation. 2- Interpréter le comportement hydrique du matériau sur chemin de drainage – imbibition en relation avec l’analyse de sa microstructure. 3- Fournir d’un point de vue général une base de données et d’analyses exhaustive permettant le développement et la calibration de modèles de comportement des sols fins proches de la saturation, en particulier en considérant des chemins de chargement hydromécanique complexes. Pour l’ensemble de cette étude, le matériau est considéré sous deux états : soit à l’état de pâte (matériau normalement consolidé) préparée à une teneur en eau proche de la limite de liquidité, soit sous forme compactée (matériau sur-consolidé) à différentes énergies de compactage et différentes teneurs en eau initiales
This thesis concerns the experimental characterization of a silty sand from the Livet - Gavet dam (38) as part of the ANR TerreDurable project, for following objectives: 1- Through laboratory tests, characterize the hydro-mechanical behaviour of a fine silty sand (Type A1 in the GTR classification) according to its saturation state. In this study, particular emphasis is placed on the characterization of this behaviour in the near-saturated domain. 2- Interpret the water behaviour of material on the drainage - imbibition cycles, in relation to the analysis of its microstructure. 3- From a general point of view, provide a comprehensive database and analysis allowing the development and calibration of models of near-saturated fine soil's behaviour, in particular, by considering complex hydro-mechanical loading paths. For all tests in this study, the material is considered in two states: either in the state of paste (normally consolidated material) prepared at water content close to the limit of liquidity, or in compacted state (over consolidated material) at different compaction energies and different initial water contents

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Singh, Jaspreet. "Physical behavior of superabsorbent hydrogels in sand". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0015/NQ44587.pdf.

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Singh, Jaspreet 1969. "Physical behavior of superabsorbent hydrogels in sand". Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35618.

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Swelling equilibrium and kinetics of two commercial superabsorbent gel particles---sodium polyacrylate spheres and polyacrylamide-co-potassium acrylate grains---were studied in water and in sand at room temperature. Equilibrium experiments involved swelling gel particles at different depths in saturated sand columns packed with different sand sizes. Kinetic experiments were performed in a two-dimensional cell; both gel particle size and sand particle size were varied. Water flow in gel-conditioned sand was also investigated in columns and the two-dimensional cells for different gel dosages.
The equilibrium swelling degree of gels in saturated sand was less than in water; decreasing sharply with depth in the first few centimeters, independent of sand particle size, then decreasing gradually with depth. A model was developed to describe equilibrium swelling in sand using the Flory model for polymer gels and a Cavity-Expansion model for frictional sand.
For individual gel particles the kinetic relationship between the fractional approach to equilibrium and the square root of time was sigmoidal for swelling in water and in saturated sand. This relationship was described by a model based on Fick's first law which accounted for the movement of the boundary of the gel and the time variation of the polymer volume fraction at the surface.
When water was distributed from the top of a uniform gel-conditioned bed, a gel layer formed on the surface. The gel particles, initially in the sand, were set free by the impact of the water. The released gel particles settled less rapidly than the denser sand particles. One minute after the initial disturbance of the dry sand-gel mixture, the water-borne particles settled on the surface to form a swelling gel layer.
In the water flow experiments the advance of the wetting front was impeded, while surface movement increased, with increasing gel dosages. Two models were developed to describe flow in gel-conditioned sand: Swelling Soil model and Instantaneous Equilibrium model. Both models were based on Darcy's law and accounted for the movement of solids.

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Arefi, Mohammad Jawad. "Dynamic Characteristics and Evaluation of Ground Response for Sands with Non-Plastic Fines". Thesis, University of Canterbury. Civil & Natural Resources Engineering, 2014. http://hdl.handle.net/10092/9173.

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Deformational properties of soil, in terms of modulus and damping, exert a great influence on seismic response of soil sites. However, these properties for sands containing some portion of fines particles have not been systematically addressed. In addition, simultaneous modelling of the modulus and damping behaviour of soils during cyclic loading is desirable. This study presents an experimental and computational investigation into the deformational properties of sands containing fines content in the context of site response analysis. The experimental investigation is carried on sandy soils sourced from Christchurch, New Zealand using a dynamic triaxial apparatus while the computational aspect is based on the framework of total-stress one-dimensional (1D) cyclic behaviour of soil. The experimental investigation focused on a systematic study on the deformational behaviour of sand with different amounts of fines content (particle diameter ≤ 75µm) under drained conditions. The silty sands were prepared by mixing clean sand with three different percentages of fines content. A series of bender element tests at small-strain range and stress-controlled dynamic triaxial tests at medium to high-strain ranges were conducted on samples of clean sand and silty sand. This allowed measurements of linear and nonlinear deformational properties of the same specimen for a wide strain range. The testing program was designed to quantify the effects of void ratio and fines content on the low-strain stiffness of the silty sand as well as on the nonlinear stress-strain relationship and corresponding shear modulus and damping properties as a function of cyclic shear strains. Shear wave velocity, Vs, and maximum shear modulus, Gmax, of silty sand was shown to be significantly smaller than the respective values for clean sands measured at the same void ratio, e, or same relative density, Dr. However, the test results showed that the difference in the level of nonlinearity between clean sand and silty sands was small. For loose samples prepared at an identical relative density, the behaviour of clean sand was slightly less nonlinear as compared to sandy soils with higher fines content. This difference in the nonlinear behaviour of clean sand and sandy soils was negligible for dense soils. Furthermore, no systematic influence of fines content on the material damping curve was observed for sands with fines content FC = 0 to 30%. In order to normalize the effects of fines on moduli of sands, equivalent granular void ratio, e*, was employed. This was done through quantifying the participation of fines content in the force transfer chain of the sand matrix. As such, a unified framework for modelling of the variability of shear wave velocity, Vs, (or shear modulus, Gmax) with void ratio was achieved for clean sands and sands with fines, irrespective of their fines content. Furthermore, modelling of the cyclic stress-strain behaviour based on this experimental program was investigated. The modelling effort focused on developing a simple constitutive model which simultaneously models the soil modulus and damping relationships with shear strains observed in laboratory tests. The backbone curve of the cyclic model was adopted based on a modified version of Kondner and Zelasko (MKZ) hyperbolic function, with a curvature coefficient, a. In order to simulate the hysteretic cycles, the conventional Masing rules (Pyke 1979) were revised. The parameter n, in the Masing’s criteria was assumed to be a function of material damping, h, measured in the laboratory. As such the modulus and damping produced by the numerical model could match the stress-strain behaviour observed in the laboratory over the course of this study. It was shown that the Masing parameter n, is strain-dependent and generally takes values of n ≤ 2. The model was then verified through element test simulations under different cyclic loadings. It was shown that the model could accurately simulate the modulus and the damping simultaneously. The model was then incorporated within the OpenSees computational platform and was used to scrutinize the effects of damping on one-dimensional seismic site response analysis. For this purpose, several strong motion stations which recorded the Canterbury earthquake sequence were selected. The soil profiles were modelled as semi-infinite horizontally layered deposits overlying a uniform half-space subjected to vertically propagating shear waves. The advantages and limitations of the nonlinear model in terms of simulating soil nonlinearity and associated material damping were further scrutinized. It was shown that generally, the conventional Masing criteria unconservatively may underestimate some response parameters such as spectral accelerations. This was shown to be due to larger hysteretic damping modelled by using conventional Masing criteria. In addition, maximum shear strains within the soil profiles were also computed smaller in comparison to the values calculated by the proposed model. Further analyses were performed to study the simulation of backbone curve beyond the strain ranges addressed in the experimental phase of this study. A key issue that was identified was that relying only on the modulus reduction curves to simulate the stress-strain behaviour of soil may not capture the actual soil strength at larger strains. Hence, strength properties of the soil layer should also be incorporated to accurately simulate the backbone curve.

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SENEZ, PHILLIPE CAMPELLO. "BEHAVIOR OF POLYETHYLENE TEREPHTHALATE (PET) FIBERS REINFORCED SAND". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=27669@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
PROGRAMA DE EXCELENCIA ACADEMICA
O presente estudo teve como principal objetivo demonstrar que fibras derivadas da reciclagem de garrafas PET (Polietileno Tereftalato), confeccionadas com 100 porcento do resíduo, pela indústria têxtil, podem ser uma boa alternativa se utilizadas como reforço de solos, quando submetidos a diferentes níveis de cargas. Buscando uma melhor aplicabilidade para este material, foram executados ensaios de compressão triaxial drenados em laboratório, bem como ensaios de prova de carga em placa e também com simulação de um talude em modelo físico reduzido, para a determinação do comportamento mecânico de uma areia e do compósito areia-fibras PET. Para os ensaios triaxiais drenados, foram utilizadas fibras PET com dois títulos (correspondente ao diâmetro das fibras) e comprimentos distintos (1,4 dtex com 38 mm e 3,3 dtex com 56 mm), inseridas aleatoriamente na massa de solo, onde foi utilizado o teor de 0,5 porcento de fibras, em relação ao peso seco do solo, teor de umidade de 10 porcento e densidade relativa de 50 porcento. Os resultados mostraram que o comportamento da areia pura é influenciado pela adição de fibras PET, melhorando os parâmetros de resistência, como o intercepto coesivo e o ângulo de atrito, definidos pelo critério de Mohr-Coulomb. O compósito reforçado com as fibras PET de menor título e menor comprimento apresentou um maior ganho na resistência ao cisalhamento, mas ambos os compósitos, em comparação ao solo não reforçado, apresentaram uma maior resistência. Para os ensaios de prova de carga em placa e para a simulação do talude, ambos realizados em modelo físico reduzido, foram utilizadas as fibras de menor título e menor comprimento como elemento de reforço. Observa-se que a inserção das fibras PET melhora o comportamento carga-recalque da areia pura, onde o compósito reforçado apresenta uma maior capacidade de suporte e a redução dos recalques, bem como uma mudança na propagação e formação das fissuras ao redor da placa. Na simulação do talude, a inserção das fibras PET promove uma alteração completa no mecanismo de ruptura ocorrido no compósito, quando comparado à ruptura da areia pura. Ressalta-se o emprego positivo das fibras PET para aplicação como reforço de solos em obras geotécnicas (como por exemplo, em camadas de aterros sanitários, aterros sobre solos moles, reforço de taludes, base de fundações superficiais e controle de erosão), além de eliminar problemas atuais de disposição de resíduos, dando um fim mais nobre a este material, com benefícios ambientais, sociais e econômicos.
The main objective of this study was to demonstrate that fibers derived from the recycling of PET (Polyethylene Terephthalate) bottle, 100 percent made from the residue by the textile industry, can be a good alternative if used as reinforcement of soil, when submitted to different load levels. Looking for a better applicability for this material, were executed drained triaxial compression tests in laboratory, as well as plate load tests, also with slope simulation in a reduced physic model, to evaluate the mechanical behavior of a sand and a composite sand-PET fibers. For the drained triaxial tests, were used PET fibers with two different titles (corresponding to the fiber diameters) and lenghts (1,4 dtex com 38 mm e 3,3 dtex com 56 mm), distributed randomly in the soil mass, where was used a fiber contente of 0,5 percent by relation to the soil s dry weight, moisture content of 10 percent and relative density of 50 percent. The results showed that the pure sand behavior was influenced by the addition of PET fibers, improving the strenght parameters as the cohesion intercept and the friction angle, defined by the Mohr-Coulomb criteria. The composite reinforced with PET fibers with minor title and lenght presented a better improvement in the shear strenght, but both composites, compared to the non reinforced soil, showed greater resistence. For the plate load tests and for the slope simulation, both performed in a reduced physic model, it was used the fiber with minor title and lenght as reinforcement element. The addiction of PET fibers improve the load-settlement behavior of the sand, where the reinforced composite shows a greater bearing capacity, a reduction of the settlements and a change in the propagation and formation of fissures around the plate. In the slope simulation, the addiction of PET fibers promove a complete alteration in the rupture mechanism that occurred in the composite, when compared to the rupture of the pure sand. It is highlighted the positive use of PET fibers for application as soil reinforcement in geotechnical works (as an example, in landfill layers, embankment on soft soil, slope reinforcement, base of shallow foundations and erosion control), eliminating current problems of waste disposal, giving a noble end to this material, with environmental, social and economical benefits.

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15

Wang, Yu-Sheng, i 王佑生. "Research on liquefaction behavior of silty sand". Thesis, 1996. http://ndltd.ncl.edu.tw/handle/39442945196103299988.

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16

Hung, Chin-tzung, i 洪進宗. "Anchorage Behavior of Removable Anchorsin Silty Sand". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/10326471692198987896.

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碩士
國立成功大學
土木工程學系碩博士班
97
Tie-back anchors are selected to use for underground excavation in the metropolis to increase construction efficiency. It is also used as retaining struts which are limited to be used in the basement construction. The purpose of this study is to estimate the ultimate anchorage capacity and to analyze the deformation for the removable and extractable anchors used in silty sand deposits. The results of this study can be used as a reference for the anchor design and construction in underground engineering. This study based on the results of full scale anchors proving test and suitability test in field around Kaohsiung-Zouing area. The tensile loading, duration and deformation during testing are measured to determine the relationship between the ultimate anchorage capacity and elastic-plastic deformation. The results show that the failure mode of the removable and extractable anchors embedded in sility sand is the pull-out failure along the interface of anchorage and soil. The unit ultimate anchorage capacity is about 1 kg/cm2, and the ultimate loading is smaller while the anchorage segment length is longer than critical length. From the plastic deformation curve, the plastic deformation will be smaller while the fix length of grout is shorter. The anchorage capacity is mainly from the frictional force between grout and soil. The frictional force is increased with the plastic deformation.

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17

Goyal, Paritosh. "Dilatancy of Silty Sand at Varied Densities". Thesis, 2013. http://dspace.dtu.ac.in:8080/jspui/handle/repository/14227.

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This work considers results of 180 drained tri-axial compression tests out of which 90 were successfully completed sharing up to large strain (20-25%). The results are analyzed with the aim to capture deviator stress v/s volumetric strain under different test conditions of relative densities and mean confining pressure. The sample was prepared in laboratory at varied relative densities. It is considers the effect of plastics fines on shear strength of sands. The properties of clean sands pertaining to shear strength have been studied extensively. The behavior of natural sands is normally influenced by the amounts of silt and / or clay. The critical state has been selected from tri-axial test data and care has been taken to ensure that true steady states arrived. Test procedures and the intrinsic properties of the material being tested are well controlled. The empirical shear strength fitting parameters (Q & R) for silty sands was compared with the existing literature for non-plastic silty sands. The values of shear strength fitting parameters (Q & R) found out for a selected sample was found to be slightly less than the conventional values. The main aim of this work is to identify the behavior of silty sand of different fineness at varied relative densities.
Prof. A.Trivedi (Professor) & Mr. Naresh Kumar (Assistant Professor

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18

Tang, Hsiao-Wen, i 唐小雯. "Anchorage Behavior of Tied-Back Anchors in Silty Sand". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/77551827461090256203.

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碩士
朝陽科技大學
營建工程系碩士班
94
A constitutive model for silty sand named “SHASOVOD” combined FLAC3D software was used to study the anchorage behavior of tied-back anchors in silty sand. A field test program was conducted to verify the applicability of the numerical program; the parametric studies were then carried out by numerical analyses. It was found that the numerical results are in a good agreement with those by field tests. The friction force dominates the anchorage capacity of a shaft tension anchor. Whether the yielding zone of an anchor develops to ground surface and structural wall or not depending on the overburden depth H and the embedded depth Z, this study have been suggested the minimum overburden depth Hmin and minimum embedded depth Zmin herein. It can be found, as the relative density of soil or the fixed length of an anchor increased, the yielding zone also expanded. When the embedded depth, the overburden depth or the fixed length of an anchor increased, the anchorage capacity also increased. Increasing fixed length should be a better method to increase the anchorage capacity; ultimate load per unit fixed length was about 55kN/m. However, when the fixed length of an anchor is greater 30 m, the incremental of anchorage capacity per unit fixed length was decreased due to progressive yield of friction stress along fixed end. According to the numerical results, when the inclination angle, overburden depth, embedded depth, or fixed length increased, the coefficient of lateral earth pressure Kf decreased. The coefficient Kf always less than the coefficient of passive earth pressure Kp; however, it was greater than the coefficient of earth pressure at rest K0.

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19

Kuo, Chih-Ling, i 郭芷伶. "Uplift Behavior of Conical Shape Anchors in Silty Sand". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/16025251376850647562.

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碩士
朝陽科技大學
營建工程系碩士班
89
ABSTRACT A series of triaxial tests for silty sand was performed to obtain the parameters needed for establishing a dilatant strain hardening-softening model, SHSE. The model and FLAC software are used to carry out the numerical analysis to study the anchorage behavior of cone-shape anchors in silty sand. To emphasize the feasibility of the numerical method, this research uses the results of field tests to verify the results of numerical analyses. It was found that the anchorage capacity come from frictional force and end resistance, but frictional force dominates the anchorage capacity, end resistance could be neglect. The pullout resistance increased with based diameter of anchors, free length and fixed length of anchors. As total length of anchor is less than 30m, the progressive yield was not evidence, so increasing fixed length is the most effective way to increase anchorage capacity. In addition, the anchor behavior predicted by numerical analyses are in good agreement with to the field tests. In order to reduce the time consumption for numerical study, the relationship between load and displacement are correlated with the relative density of sand, the free length, the based diameter of anchor. A simple program ”Conical Anchor” is then established. The program can significantly cut down the compute time. In addition, the anchor behavior predicted by this program is very closed to the field test.

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20

Chen, Chih-wei, i 陳志瑋. "Uplift Behavior of Frictional Anchor Groups in Silty Sand". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/98699964650844034305.

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碩士
朝陽科技大學
營建工程系碩士班
96
Both numerical analyses and field tests were accomplished to elucidate the anchorage behavior of frictional anchor groups in silty sand. A series of triaxial tests was performed on specimens taken from test site, based on the frame of constitutive model for the cohesionless soil named SHASOVOD (A continuous strain hardening- softening and volumetric dilatancy model), to obtained the parameters needed for the model. This study along with FLAC3D software to analyze behaviors of single anchors and anchor groups in silty sand. In addition, to verify the suitability of the numerical program, filed tests on a single shaft anchors and an anchor group arranged in 2*2 matrix form were conducted in silty sand. After the calibration, a succession of parameteric analyses was carried out to study the anchorage behaviors of single shaft anchors and anchor groups in silty sand. It was found from triaxial tests on silty sand, the shear strength increases as relative density and confining pressure increases. The failure plane occurs when the deviator stress reaches peak point. Hence, the shear strength decreases to residual state and tends to constant as axial strain increases. The volume decreases in the beginning, then dillates, and finally comes to the steady state. This stress-strain phenomenon meets the SHASOVOD model. It can be seen from field test results, the ultimate load of 542kN was estimated meanwhile the anchor head displacement reached 13cm for a single anchor with diameter of 15cm, free length of 10m, and fixed length of 15m; while the ultimate load of 522kN was measured with respect to the average of anchor head displacement of 12.5cm for a 2*2 anchor group with spacing of 60cm, efficiency of an anchor group was computed to be 95%. The load-displacement relations and ultimate loads calculated from numerical analyses were closed to those measured by field tests not only for the single anchor but also for the anchor group. When a 2*2 anchor group with spacing of 2D (D: anchor diameter), efficiency of the anchor group was calculated to be only 75%~ 80%. There is no interference when spacing was 6D, and the efficiency of an anchor group could more than 95%. The yielding zone of the anchor groups increase as overburden depth increase. The efficiency of anchor groups can be eliminated as the anchor spacing are increase horizontally. It can be found from the numerical results, the efficiency of 3*3 anchor group is greater than that of 2*2 anchor group.

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21

Chang, Yi-Sheng, i 江易昇. "Uplift Behavior of Multiple–Anchorage Anchor Groups in Silty Sand". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/91856197565887397568.

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碩士
朝陽科技大學
營建工程系碩士班
97
ABSTRACT Both numerical analyses and field tests were accomplished to elucidate the anchorage behavior of multiple–anchorage anchor groups in silty sand. Based on the results of triaxial tests, the parameters needed for SHASOVOD model (A continuous strain hardening- softening and volumetric dilatancy model) were obtained, in conjunction with FLAC3D software to analyze behaviors of multiple–anchorage single anchor and anchor groups in silty sand. In addition, field anchor tests were performed to verify the suitability of the numerical analysis. After the calibration, a succession of parametric analyses was carried out to study the anchorage behaviors of multiple–anchorage single anchor and anchor groups in silty sand. It can be seen from field test results, the ultimate load of 642kN was estimated meanwhile the anchor head displacement of 15cm for an anchor with diameter of 15cm, free length of 10m, and fixed length of 15m; while the ultimate load of 609kN was measured with respect to the average of anchor head displacement of 14.5cm for a 2*2 anchor group with spacing of 60cm, efficiency of an anchor group y was computed to be 95%. The load-displacement relations and ultimate loads calculated from numerical analysis were closed to those measured by field tests not only for the single anchor but also for the anchor group. Anchorage capacity of vertical multiple–anchorage anchor is mainly from friction force. When the upper anchorage body located in fixed end, and a distance of 10m from the anchor bottom, the greatest anchorage capacity can be found. However, even though the perfect anchorage spacing was applied, the ultimate loads of two anchorage bodies do not develop simultaneously. Therefore, anchorage capacity of an anchor is not equal to the combination of those ultimate loads which created by two anchorage bodies. When a 2*2 anchor group with spacing of 2D (D: anchor diameter), efficiency of the anchor group y was calculated to be only 66%~ 78%. There is no evident interference when spacing of anchor group is greater than 6D, and the efficiency of an anchor group y is more than 98%. The efficiency of an anchor group decreases with an increase in overburden depth, and increases with an increase in fixed length. However, the efficiency of anchor groups can be eliminated as the anchor spacing increases horizontally. It shown from the numerical results, the interference of 3*3 anchor group is greater than that of 2*2 anchor group.

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22

Hsu, Po-Shun, i 許博舜. "Uplift Behavior of the Underreamed Anchor Groups in Silty Sand". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/81005312260760896465.

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碩士
朝陽科技大學
營建工程系碩士班
96
Both numerical analyses and field tests were accomplished to study the anchorage behavior of underreamed anchor groups in silty sand. A series of triaxial tests were performed on specimens taken from test site, based on the constitutive model of cohesionless soil named SHASOVOD (A continuous strain hardening- softening and volumetric dilatancy model), to obtained the parameters needed for the model. The model and the parameters were then quoted to evolve a numerical program by FORTRAN language, along with FLAC3D software to analyze behaviors of single anchors and anchor groups in silty sand. In addition, to verify the suitability of the numerical program, filed tests on a single underreamed anchors and an anchor group arranged in 2*2 matrix were conducted in silty sand. After the calibration, a succession of parameteric analyses was carried out to study the anchorage behaviors of single underreamed anchors and anchor groups in silty sand. It can be seen from the results of field test, an ultimate load of 650kN was estimated meanwhile the anchor head displacement reached 11cm for a single anchor with diameter of 40cm, free length of 10m, and fixed length of 5m; On the other hand the ultimate load of 610kN was measured with respect to the average of anchor head displacement of 9.4cm for a 2*2 anchor group with spacing of 160cm. Therefore, efficiency of an anchor group was computed to be 94%. It can be seen from the numerical results of 2 by 2 matrix-arranged anchors, no matter which it changes the fixed length or overburden depth, when the anchors were spaced was more than 7.5 times of anchor diameter D, it can eliminate the influence of anchorage capacity. Yield zone of soil develops to ground surface and it occurs superposition, when overburden depth of 5D and horizontal space of 2.5D (1m). The superposition of yielding zones will not be able to occur and the yield zone of soil will not develop to the surface when the anchors apart were spaced more then 5 D apart horizontally. Meanwhile, it can be found from the numerical results, the efficiency of 3*3 anchor group is greater than that of 2*2 anchor group.

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23

Tseng, Wen-Liang, i 曾文良. "Uplift Behavior of Cone-Shape Anchors in Taipei Silty Sand". Thesis, 2000. http://ndltd.ncl.edu.tw/handle/90873854156799897419.

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碩士
國立臺灣科技大學
營建工程系
88
This research is aimed to study the anchorage behavior of cone-shape anchor in Taipei silty sand. Three methods namely triaxial test, full-scale anchors test and numerical study are used to investigate the behaviors of silty sand and cone-shape anchor. The behavior of cone-shape anchor is studied by the SHSE numerical model. The parameters used by this model are obtained from the triaxial test. FLAC program is adopted here to numerically analyze the behavior of anchor in Taipei silty sand. Generally, the numerical results are in good agreement with the full-scale anchor tests. The influence of cone dimension and soil properties on the anchorage capacity and the load-displacement behavior of anchor are investigated. For anchors with the same length, the cone-shape anchor has a higher ultimate anchorage capacity than shaft anchor. If the fixed length reaches 30m, no progressive failure is observed in cone-shape anchor when anchor reaches its peak pull-out resistance. Therefore, increasing fixed end length in cone-shape anchor could effectively increase the anchorage capacity.

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24

GOSWAMI, PANKAJ. "INFLUENCE OF NATURAL POLYMER ON GEOTECHNICAL BEHAVIOR OF SILTY SAND". Thesis, 2016. http://dspace.dtu.ac.in:8080/jspui/handle/repository/14689.

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ABSTRACT Soil roads are help to connect the network between rural and urban areas for peoples to survive their life and for their needs. There is need for a proper geometric design and good pavement condition. Due to increase in traffic and with high magnitude of wheel load causes rapid fractures in road pavements. So there is a need to improve the density and strength of sub grade soil. In this study a attempt is made for improving the geotechnical behaviour of silty soil using natural polymer. India is the largest consumer of sugar in world. In India every day million tons of sugar crushed and average gives a tons of sugar, molasses, bagasse and of press mud [4]. Initially it seems very costly but actually in practical way it proved to be economically. Hence experimental investigation has been carried out to study the influence of molasses geotechnical properties of soil. The important properties which are conducted in study are specific gravity, consistency limits, max dry density, optimum moisture content, California bearing ratio and unconfined compressive test. This study has to be carried out for utilization of cane molasses for improving the soil properties of sub-grade and properties of soil mix with molasses at different varying percentage. In this investigation cane molasses was used. Soil samples are prepared with varying percentage of cane molasses at 3%. 4.5%, 6%, 7.5%. The soil used in this study was silty sand (SM). The results show that with the use of molasses, there was increase in unconfined compressive strength and CBR value of soil. These results seem to be more effective and beneficial in modification of construction of road pavement. KEYWORDS: molasses, soil stabilization, CBR value.

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25

Huang, Yong-Fan, i 黃永帆. "Uplift Behavior of Matrix Arranged-Frictional Anchor Groups in Silty Sand". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/01445361854737040563.

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碩士
朝陽科技大學
營建工程系碩士班
100
Numerical analyses were performed to study the behavior of anchor groups in silty sand. According to the constitutive model for the cohesionless soil, SHASOVOD (A continuous strain hardening-softening and volumetric dilatancy model), a series of triaxial tested results was adopted to obtained the parameters of the model. In conjunction with FLAC3D software, a succession of parametric analyses was carried out to study the anchorage behaviors of anchor groups in silty sand formation. According to the numerical results, when a 4*4 anchor group with a spacing Sh of 4D (D: anchor diameter), the efficiency of the anchor group was calculated to be only 62%~ 71%. As the Sh is 8D, the efficiency of an anchor group exceeds 95%. The interference of a 4*4 anchor group decreases with an increase in overburden depth, it increases with an increase in fixed length. However, interference almost can be eliminated as the anchor spacings exceed 10D. It can be found from the numerical results, the interference of a 5*5 anchor group is larger than that of a 4*4 anchor group. Obviously, the more the anchors, the more the interference in the anchor group. Keywords：Silty sand, Numerical analysis, Martix-arrangement, Efficiency of an anchor group

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26

Yao-Tao, Huang, i 黃耀道. "Cyclic Behavior Analysis of a Silty Sand in Central Western Taiwan". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/61906766079795883027.

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博士
國立交通大學
土木工程系所
95
Central Western Taiwan is covered by a thick deposit of alluvial silty fine sand. The Chi Chi earthquake of 1999 triggered extensive soil liquefaction in this area. The simplified procedure commonly used for liquefaction potential assessment starts by considering the granular material as clean sand. For sand with fines (particles passing #200 sieve), an adjustment for the fines content (FC) is required. The back analysis of liquefaction potential using the simplified procedure for the silty sand in this region often results in different conclusions because of the fines content adjustment and in situ test method used for the analysis. There has been no consensus as to how the fines affect the undrained shear strength of silty sands. The knowledge on how fines affect the in situ test results is even more limited. The need and accuracy of FC adjustment in the simplified procedure have not been rigorously verified. Mai Liao sand and Yuan Lin sand can both be considered as typical sand in Central Western Taiwan. The author compiled results from a series of cone penetration tests (CPT) in a calibration chamber and monotonic/cyclic triaxial tests on Mai Liao sand (MLS) and made systematic analyses. For MLS the shear wave velocity (Vs) and cyclic resistance ratio (CRR) decrease with FC. FC does not have a significant effect on the Vs-CRR correlation. Under the framework of simplified procedure there does not appear to be a need for FC adjustment. For FC of 0 and 15%, CPT can be viewed as drained test, and there was no obvious difference in the correlation between cone tip resistance （qc） and CRR as FC changed from 0 to 15%. As FC reached 30%, CPT becomes partially drained, and the effect on qc-CRR correlation becomes significant. This finding shows that it is the drainage conditions not FC itself that affect the qc-CRR correlation. The above conclusion was made entirely from tests on remolded specimens. Research has indicated that due to discrepancies in soil fabrics, there can be significant differences in the behavior between natural and remolded soil specimens. The author used a modified Laval sampler to retrieve undisturbed silty sand samples under ambient temperature and preserved samples by freezing above ground. Techniques of cutting frozen Laval samples and thawing soil specimens in triaxial were developed. The cost of taking Laval sample and freezing above ground is much lower than ground freezing and coring. With this new procedure, the author took a series of Laval samples, performed CPT and field shear wave velocity measurements at a test site in Yuan Lin. Monotonic/cyclic triaxial tests with shear wave velocity measurements using bender elements were conducted on specimens trimmed from the Laval samples. The quality of the Laval samples was verified first. The Vs and CRR values from Laval samples were significantly higher than those of remolded specimens with the same density and stress states. Similar to MLS, the Vs and CRR decrease with FC for Yuan Lin sand (YLS). FC had no effect on the Vs-CRR correlation for both natural and remolded YLS. However, the FC had to be much higher what was learned from MLS for CPT in natural YLS to be partially drained. For CPT in natural alluvial soil, the drainage conditions are strongly influenced by the possible existence of thin layers of clean sand. The effects of drainage during CPT due to these thin permeable layers may not have a direct relationship with the fines content of the silty sand mass. In order to account for the drainage effects, the CPT pore pressure dissipation test may be used as a basis for the qc-CRR correlation adjustments. Keywords：sand, fines content, cyclic resistance ratio, Laval sample, liquefaction potential, cone penetration test, shear wave velocity

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27

Lin, Ying-Chieh, i 林英傑. "Anchorage Behavior of the Inclined-Multiple-Anchorage Anchors in Silty Sand". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/70230997631159965039.

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碩士
朝陽科技大學
營建工程系碩士班
95
A continuous strain hardening-softening and volumetric dilatancy model named SHASOVOD, and FLAC3D software were adopted to study the anchorage behavior of inclined-multiple-anchorage anchors in silty sand. To enhance the applicability of numerical analyses, the results of field tests are compared with those from numerical analyses. After the calibration, parametric studies were then carried out by numerical analyses. It was found that the numerical results are in a good agreement with those by field tests. The friction force dominates the anchorage capacity of a shaft multiple anchorage anchor. It can be inferred, the optimum position of the upper anchorage body is 6m form the bottom for a double-anchorage anchor. Moreover, for a triple-anchorage anchor, a distance of 12m is the best location for upper anchorage body from the middle one. Even though anchorage bodies were installed in the condition of optimum location, the anchorage capacity could not be the summation of the ultimate load of each anchorage body, this phenomenon is caused by carried load of each anchorage body do not reach peak values at same anchor displacement. Whether embedded depth, overburden depth or fixed length of an anchor increased, the anchorage capacity of an anchor also increased. For a multiple-anchorage anchor, increasing fixed length should be the best choice to increase the anchorage capacity, ultimate load per unit fixed length was around 60kN/m. However, as the fixed length of a double-anchorage anchor is greater than 30m, the anchorage capacity per unit fixed length was decreased due to progressive yield of friction stress along fixed end. Instead, a triple anchorage methodology could be applied to conquer the progressive yield of above situation. A tension force was generated beneath the anchorage body, Hence the grouted body was cracked and led to an erosive steel strand. No utilization to a multiple-anchorage anchor is really complete without applying a double protection on fixed length.

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28

Hung-TungHsu i 許紘東. "A Study on Volumetric Strain Behavior of Low Plasticity Silty Sand". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/85243946670773476533.

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碩士
國立成功大學
土木工程學系碩博士班
101
Many severe natural disasters resulted from soil liquefaction during earthquakes in the world. The ground subsidence due to the soil liquefaction was also resulted in secondary damage of the structures. In recent years, soil liquefaction induced from the earthquakes was found in many strata with low-plastic silts around the world. Therefore the study of the dynamic behavior of low-plasticity silt of is necessary. The major difficulty during investigating the low-plasticity silt was unable to obtain the soil specimen which can represent the field conditions; especially the low rate of sampling. In this study the Gel Push sampler was developed, with which the undisturbed low-plastic soil specimens can be obtained. The purpose of this study was to investigate the dynamic strength of the low-plasticity silt and the behavior of volumetric strain after liquefaction. The effect of fines content and void ratio on the dynamic behavior of the low-plasticity silt is also studied; the influence of the sample disturbance is investigated as well. The results indicated that cyclic shear ratio will increase as the void ratio decreased on the behavior of dynamic strength. The cyclic shear ratio of a remolded sample is lower than that of an undisturbed one. Therefore the dynamic strength of low-plastic silt decreases with reducing the degree of disturbance. On the behavior of volume change, it decreases with decreasing of the void ratio and the fines content. The volume change after liquefying of a remolded sample is much noticeable than that of an undisturbed one. With low-plasticity silt on the behavior of dynamic strength and volume strain behavior of research to be used for evaluation of liquefaction and liquefaction caused by compaction settlement amount, as a reference for engineering design.

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29

YU, SHAN-RU, i 游姍儒. "Anchorage Behavior of Inclined 2*2 Arrayed Anchors in Silty Sand". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/uz87yx.

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碩士
朝陽科技大學
營建工程系
106
This study adopts the numerical method to investigate the anchorage behavior of 2*2 arrayed anchors in silty sand. The numerical results are verified by in-situ results. The field anchor tests are conducted at Jhangbin Industrial Park in Lukang, Changhua. A strain hardening-softening and volumetric expansion model (SHASOVOD) is carried out to perform the numerical analysis. The numerical results reveals that the numerical analyzed results are consistent with in-situ test. When the spacing between neighboring anchors is 4D (where D is the anchor diameter), the efficiency of an anchor group is approximately 88%. The yielding zones of soil around the anchors are highly superposed. When the spacing is 10D, the efficiency of anchor groups is about 99%; the behavior of each anchor in the anchor group is similar to the behavior of a single anchor. Because the inaccurate design of tieback system in deep excavation in Zhubei City which constructed by a certain company had induced site disaster. For avoiding the yielding zone of anchor develops to ground surface and diaphragm wall, this study suggested that the overburden depth and free length all exceed 2m.

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30

Lin, Yu-Jung, i 林煜融. "Anchorage Behavior of Shaft Anchors in Silty Sand of the Taipei Basin". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/22362624964486027593.

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碩士
朝陽科技大學
營建工程系碩士班
89
A series of triaxial tests have been performed to obtain the parameters need for a sand model, SHSE (A model for strain hardening/softening of dilated sand). The numerical model and FLAC software were carried out to study the uplift behavior of shaft anchors in silty sand of the Taipei Basin. To emphasize the applicability of the numerical model, the results obtained from the field tests are used to verify the results of numerical analyses. It is found that the friction stress along the fixed anchor end of single anchorage type anchor shows progressive yielding not only tension type but also compression type anchor. Due to progressive yielding, a less than linear behavior is found between anchorage capacity and total anchor length when the latter is longer than 125D, where D is the diameter of fixed anchor end. The progressive yielding could be overcome due to load transfer upward and downward if anchorage body is chosen in midpoint of fixed anchor end for compound type anchor. Therefore, compound type anchor is the best choose among all single anchorage type anchors. In order to overcome the behavior of progressive yielding, this research develops a multiple anchorage method to dissipate the phenomenon of stress concentration. The optimum anchorage position is evaluated from numerical study herein. A linear relationship is found between anchorage capacity and anchor fixed length when the latter is less than 50m. It can been seen from parameters study that the relative density of sand could not affect the pullout force of single anchorage type anchor due progressive yielding, but the anchorage capacity of multiple anchorage type anchor could increase linearly with relative density of sand. In addition, the load-displacement behavior computed by numerical programs can give a good prediction not only single anchorage type but also multiple anchorage type of field anchors.

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31

Hung, Cheng-Jie, i 洪正杰. "The Loading Behavior of Tensile Piles and Compressive Piles in Silty Sand". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/66729432087564449115.

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碩士
朝陽科技大學
營建工程系碩士班
89
ABSTRACT Both numerical analysis and field tests have been performed to study the behavior of compressive and tensile piles in silty sand. A Strain Hardening-Softening and volume Expansion model called "SHSE" for silty sand will be adopted to establish the parameters need for SHSE model from triaxial test. The model and FLAC software are used to carry out the numerical analysis for piles. Based on the numerical results, a series simple calculated formulas and design charts among the total load, skin friction and end resistance with respect to displacement of pile head have been established for designer. The major subject in this study includes: (1) Comparison of load capacity between tensile pile and compressive pile. (2) The relationship among Total load, shaft capacity and end-bearing capacity with respect to displacement of pile head. (3) The influence of load capacity by the diameter, length of pile and the relative density of silty sand. (4) The load transferring along the pile. (5) The distribution of frictional stress around pile shaft. (6) The yielding conditions of soil around pile. (7) The variation of earth pressure around the pile depends on the load. The results have shown that the diameter of pile, the length of pile and the relative density of sand could affect the total load, shaft friction and end bearing of pile. In order to reduce the time consumption of numerical study, the relationship between load and displacement of pile are correlated with the relative density of sand, the diameter of pile, and the length of pile. A simple program was then established which can significantly cut down the compute time. In addition, the load-displacement behavior predicated by the program is very closed to the field test not only compressive pile but also tensile pile.

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32

Tsai, Chih-lun, i 蔡志倫. "Anchorage Behaviors of Tieback Anchor Groups in Silty Sand". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/22172907947630341372.

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碩士
朝陽科技大學
營建工程系碩士班
102
This study performed a series of numerical analyses to elucidate the behavior of tieback anchor groups in silty sand. Along with the constitutive model for the cohesionless soil named SHASOVOD (A continuous strain hardening-softening and volumetric dilatancy model), this research adopted triaxial tested results to obtain the parameters of the model. In conjunction with FLAC3D software, a succession of parametric analyses was carried out to study the anchorage behaviors of anchor groups in silty sand. According to the numerical results, when aligned tirple anchors installed in silty sand with a spacing Sh of 4D (D is the anchor diameter), efficiencies of anchor groups were calculated to be only 74% - 78%. As the Sh equaled 10D, the efficiencies of anchor groups exceeded 96% - 97%. Interference almost can be eliminated as the anchor spacing exceeded 10D for anchor groups with various overburdens and free lengths. It can be found from the numerical results, the interference of an aligned quaternary anchors was larger than that of an aligned triple anchors. Obviously, the more the anchors installed in a group, the more the interference occurs in the anchor group.

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33

Yang, Meng-Lin, i 楊孟霖. "The Friction Behavior of Interface Between Pile and Soil in Taipei Silty Sand". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/62667499733546832537.

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34

Lin, Yang Mun, i 楊孟霖. "The Friction Behavior of Interface Between Pile and Soil in Taipei Silty Sand". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/78525651055036908456.

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碩士
國立臺灣科技大學
營建工程技術學系
86
Under the design Load ( on third of Ultimate load ), the most part of the load is Carried by the pile shaft. Therefore, the purpose of this thesis is to study the behavior and load transfer of pile friction on silty sand in Taipei Basin. From the test result of modified triaxial model pile, it reveals that the shaft friction in increase with the confined pressure, the relation density of sand, the roughness of pile surface and the softness of pile materials. However, the friction behavior in independent to the loading rate. Besides the smooth steel pile, the pattern of shear stress displacement curve of model pile test display strain-soften significantly.Comparison the test result and suggestion in the building code, the friction angle of steel pile is suitable for the sand of middle density. For the concrete pile, the suggested value is reasonable and conservative. After comparing the t-z curve obtain from this research with the in-situ test, the coincidence is better for the small displacement and have some difference for large displacement.

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35

Sheng-YuanHong i 洪聖淵. "A Study on Post-Liquefaction Volumetric Strain Behavior of Low Plasticity Silty Sand". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/80188039484250960790.

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碩士
國立成功大學
土木工程學系碩博士班
100
In recent years, many severe disasters resulted from soil liquefaction during major earthquakes in the world and ground subsidence due to the rearrangement of soil grains after earthquake was also resulted in secondary damage of the structures. Previous literatures were focused on the volume change of remolded clean sand during liquefaction. However, soil liquefaction induced from earthquake was also found in strata other than clean sand, especially in many strata with low-plastic silts. In this study, the undisturbed low-plastic soil specimens are obtained by a new developed Gel Push sampler, comparison is performed on the influence of disturbance to the dynamic strength and volume change of low-plastic silt in between undisturbed and remolded conditions. The results indicated that the dynamic strength of low-plastic silt decreases with reducing the degree of disturbance during sampling and the tendency of decrease in dynamic strength is significantly with the increase in fine contents of the low-plastic silt. On the behavior of volume change, it increases with increasing of the fines content after soil liquefied and the volume change after liquefying of a remolded sample is much noticeable than that of an undisturbed one. The shear strain of a remolded sample is approaching to a critical value; however, the shear strain of an undisturbed sample is increasing steadily. Therefore, the engineering judgment has to be made as those design factors are obtained from laboratory test with remolded samples of low-plasticity silt.

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36

Szu-ChenYeh i 葉思辰. "A Study on Engineering Behavior of Non-plastic Silty Sand under Particle Crushing Conditions". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/2s85zn.

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37

Jian-DeMiao i 繆建德. "A Study on Engineering Behavior of Non-plastic Silty Sand under Internal Erosion Conditions". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/83522222014683765686.

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38

Cao, Yan-Jhen, i 曹晏甄. "Experimental and Numerical Studies on the Behavior of Inclined Dual Anchors in Silty Sand". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/19843994017473136453.

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碩士
朝陽科技大學
營建工程系
103
To evaluate the behavior of dual-inclined anchors installed in silty sand, a series of triaxial test results conducted by Ho (2005) were utilized to obtain the parameters of a continuous strain hardening-softening and volumetric dilation model, SHASOVOD. In conjunction with FLAC3D, a numerical study was carried out to analyze the behavior of horizontal-aligned-dual-inclined anchors in different conditions. Finally, by comparing with the result of anchor’s pullout test in Yilan to verify the applicability of the numerical program. By comparing the pull-out test result of single anchor and dual anchors, the load-displacement curve have a similar trend, show that the numerical analysis of this study can reach up to a certain precision, it can be conducted into the dual anchors’ research of different parameters. According to the numerical results, when the horizontal- aligned-dual-inclined anchors installed in silty sand with a spacing Sh of 4D (D is the anchor diameter), efficiency of the anchor group was calculated to be 78~79%. As the Sh equals 10D, the efficiency of an anchor group 96~98%. The study found that when the spacing Sh larger than 10D, whether the change of overburden depth , free length and anchorage length, the efficiency of an anchor group can be eliminated.

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39

Ma, Wei-Yang, i 馬維揚. "Horizontal Spacings Effects on the Anchorage Behavior of Inclined Anchor Groups in Silty Sand". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/88903351437968995815.

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碩士
朝陽科技大學
營建工程系
103
To evaluate the uplift behavior of paired and four-aligned inclined friction anchors in silty sand, a series of triaxial test results were utilized to obtain the parameters needed for the continuous strain hardening-softening and volumetric dilation model, SHASOVOD. In conjunction with FLAC3D, a numerical study was carried out to analyze the behavior of dual and four-aligned inclined friction anchors in silty sand. A field test program was conducted in silty sand within an excavating site to verify the applicability of the numerical program. Finally, parametric studies on the factors affecting the anchorage behavior were executed. According to the numerical results, when the paired & four-aligned anchors installed in silty sand with a spacing Sh of 4D (D is the anchor diameter), the efficiency of the anchor group was calculated to be approximately 74-78%. As the Sh equaled 10D, the efficiencies of an anchor group exceeded 96%-99%. When the four-aligned anchor installed in silty sand with spacings Sh of 4D, the efficiency of the inside anchors in the anchor group was calculated to be approximately 68%; however, the efficiency of the outside anchors in the anchor group was 78%； an average efficiency of 73% was found in this study. The pullout force of the inside anchors was smaller than that of the outside anchor, because yielding soils overlap around inside anchors exceeded those of outside anchors. The more the anchors installed in a group, the more the interference occurs in the anchor group.

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40

Ko, Fu-Chun, i 柯富淳. "Vertical Spacings Effect on the Anchorage Behavior of Inclined Anchor Groups in Silty Sand". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/46641754187195061261.

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碩士
朝陽科技大學
營建工程系
103
This study performed a series of numerical analyses to elucidate the behavior of inclined anchor groups in silty sand. The constitutive model for the cohesionless soil named SHASOVOD (A continuous strain hardening-softening and volumetric dilatancy model) was adopted. A series of triaxial test results were used to obtain the parameters of the model. In conjunction with FLAC3D software, this study carried out a succession of parametric analyses to study the anchorage behaviors of anchor groups in silty sand. According to the numerical results, when vertical aligned-anchors inclined in silty sand with a spacing Sv of 0.5m, the efficiency of dual anchors were calculated to be only 82.2%. As the Sv equals 2m, the efficiency of dual anchors exceeded 99%. Interference almost can be eliminated as the anchor spacing exceeded 2m for anchor groups with various overburdens and free lengths. It can be found from the numerical results, the interference of the upper anchor of the dual anchors was than that of the lower anchor. As the vertical spacing increases, the interference of the anchor group decreases.

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41

LAI, YI-CHEN, i 賴奕臻. "Vertical Spacings Effect on the Anchorage Behavior of Three Inclined Anchors in Silty Sand". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/e4mmg8.

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碩士
朝陽科技大學
營建工程系
106
Ground anchors are usally to be served as earth structure. Therefore, the understanding of anchorage behavior is demanded. Numerous researches investigate the anchorage behavior of the anchors. This study adopts numerical method to investigate the anchorage behavior of three vertical-aligned inclined anchors in silty sand. The anchor test site is located at Jhangbin Industrial Park in Lugang, Changhua, and the test results are used to verify the applicability of the numerical method. The constitutive model named SHASOVOD (A continuous strain hardening-softening and volumetric dilatancy model) and the parameters needed for the model are adopted, in conjunction with FLAC3D software to carry out the numerical analyses. The numerical results reveal that no matter which anchor dimension is analyzed, when spacing between anchors is 10D (where D is the anchor diameter), the interference of the anchors virtually disappear. When anchor spacings are 4D, the efficiency is about 85%; when spacings are 10D, the efficiency is approximately 98%. As vertical spacing between anchors is 4D, the interference of anchors is evident; as the spacing is 10D, the interference vanishes. In addition, this study suggests that both the overburden depth and free length exceed 2m to avoid the yield zones develop to ground surface and/or to diagram wall.

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42

Tsai, Ming-Chun, i 蔡旻峻. "Anchorage Behaviors of Dual-Inclined-Cone Anchors in Silty Sand". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/82596189501835889830.

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碩士
朝陽科技大學
營建工程系碩士班
101
A series of Numerical analyses were performed to study the behaviors of dual inclined-cone anchors in silty sand. According to the constitutive model for the cohesionless soil, SHASOVOD (A continuous strain hardening-softening and volumetric dilatancy model), triaxial tested results was adopted to obtained the parameters of the model. In conjunction with FLAC3D software, a succession of parametric studies was carried out to elucidate the anchorage behaviors of dual inclined-cone anchors in silty sand. The numerical results show that, for the dual inclined-cone anchors, whether the overburden depth, embedded depth and fixed length are changed or not, when the horizontal spacing Sh is 8Dt (Dt: anchor top diameter), the efficiency of the anchor group is estimated at about 86%. When Sh equals 14Dt, the efficiency of an anchor group approximates 98%, and the anchorage behavior of dual anchors is similar to two independent anchors. The interference of dual anchors decreases with the overburden depth and the embedded depth, and increases with the fixed length. Whether the overburden depth, embedded depth and fixed length are changed or not, interference almost can be eliminated as the anchor spacing exceeds 14Dt.

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43

CHAN, KAI-JEN, i 詹凱仁. "Experimental and Numerical Studies on the Behavior of Horizontally Aligned Anchor Groups in Silty Sand". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/13949111423518246459.

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碩士
朝陽科技大學
營建工程系
104
Anchors are extensively applied in geotechnical area, and are usually adopted in a group, especially the inclined anchors. This study adopted the numerical method to investigate the anchorage behavior of horizontally aligned inclined anchor groups in silty sand, the numerical results were verified by in-situ results, after that, this research carried out a series of parametric studies. Based on the SHASOVOD model (A continuous strain hardening- softening and volumetric dilatancy model) and the parameters of sandy soil needed for this model, this study employed the FLAC3D software to analyze the behavior of dual and four horizontally aligned anchors. After numerical results calibrated by experimental results, this study conducted parametric studies, such as the overburden depth, free length, anchorage length and horizontal spacing. Numerical results show that the load-displacement behaviors calculated numerically are consistent with those measured by anchor tests. When the spacing between neighboring anchors is 4D for dual anchors and four-aligned anchor group, the efficiency of an anchor group are 78% and 72%. The more the installed in a group, the more the interference occurs. The effect of the free length and overburden depth on the efficiency of an anchor group is infinitesimal. The behavior of each anchor in the anchor group is virtually identical to the behavior of a single anchor when the horizontal spacings exceed 10D.

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44

Panico, Antonio Fabrizio. "Modelling the Long Term Cyclic Behaviour of Porto Silty-sand Stabilised with Cement". Doctoral thesis, 2018. https://hdl.handle.net/10216/119075.

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45

Panico, Antonio Fabrizio. "Modelling the Long Term Cyclic Behaviour of Porto Silty-sand Stabilised with Cement". Tese, 2018. https://hdl.handle.net/10216/119075.

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46

Jeng-RongLi i 李政融. "The Study on Dynamic Behavior of Silty Sands with Fines Using Dynamic Triaxial Test". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/88270416506884111244.

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碩士
國立成功大學
土木工程學系碩博士班
98
In this study, dynamic triaxial tests were conducted by CKC cyclic triaxial test system. The sand with fines content were collected in Yuanlin of Changhua. The samples are prepared by moist tamping and the fines content of sample will be gradually adjusted under different global void ratio. The purpose of this study is to investigate the effect of global void ratio and fines content on the dynamic behavior of silty sands. The study will also integrate the data from this project and researches of silty sands collected in the central and southern Taiwan, and especially focus on the comparison and discussion of basic properties, micro-structure, mineral composition and dynamic strength within those data. According to the test results, the maximum shear modulus and dynamic strength of samples decrease with increasing fines content of samples. It declines between the range from 15% to 30% of fines content. As the fines content of samples over 60%, the maximum shear modulus and dynamic strength would gradually tend to a constant value. Generally speaking, the dynamic strength of the samples with fines content of 60% approximately reduces 25% of that of the samples with pure sand. According to the date, the specific gravity of silty sand were ranging from 2.67 to 2.75. Most of silty sands were nonplastic or low plastic with plastic index lower than 4. The liquid limits of the sands were nearly the same as the field water contents, and it can be cataloged as sensitive soil. The mean grain sizes were in between 0.08mm and 0.7mm. The range of grain size was coincided with the range of grain size which were senstive to be liquefiable. In the exploring of dynamic strength, the result show that three completely different trends including, they are "a gradual decreasing", "a gradual increasing", and "a first decreasing then increasing ".

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47

CHIU, WEN-FENG, i 邱文峰. "The Static Mechanical Behavior of Post-liquefaction under Simple Shear Conditions for Silty Sands in Taipei Basin". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/54097677381708711146.

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碩士
國立臺灣大學
土木工程學系
86
The purpose of this study is to investigate the static mechanical behavior of post-liquefaction for silty sands in Taipei basin under simple shear conditions, the problem would be the estimation of ground settlement and residual shear strength of post-liquefaction. If the residual shear stress of post-liquefaction to zero, the post- liquefaction condition is less static shear strength than the pre- liquefaction condition in the same dry density after consolidation, the rate of volume-change too. If the residual shear strain of post- liquefaction to zero, the post-liquefaction condition is higher static shear strength than the pre- liquefaction condition in the same dry density after consolidation, the rate of volume-change too. Comparision of angle of effective shearing resistance to the same dry density after consolidation on both simple shear conditions and triaxial condition, the angle of effective shearing resistance is highest to pre- liquefaction condition, the angle of effective shearing resistance is less to post- liquefaction condition.

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48

KUMAR, ARVIND. "STUDY OF SHEAR BEHAVIOUR OF SAND BLENDED WITH SILT". Thesis, 2015. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15570.

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The structure derived from compacting the soil at different water contents and energy levels can have a substantial effect on its shear strength. While the shear strength can be estimated based on the saturated shear strength parameters and the unsaturated angle of shearing resistance, limited studies have explored the variation of shear strength properties with different compaction states. In this project report, the shear strength of a sandy soil was investigated using a conventional direct shear box and triaxial test (CU) with three different normal pressures. In this project, it was aimed to observe shear strength behavior of sand blended with various percentage of silt. Three series of experiments were performed. In all series, behavior of shear strength under different testing conditions was investigated against increasing fine materials in the mixtures. Silt is used as fine material. Shear strength parameters, failure strains, stress-strain behaviors were studied. The changes in basic characteristics such as particle size distributions, consistency limits and index properties were also studied. In this investigation laboratory study on Sand (SP) blended with Silt (ML) has been carried out. Various test conducted on sand and silt were performed for the determination of following parameters: Field moisture content, Atterberg’s Limits, Grain Size Analysis, Standard Proctor’s Compaction test, Direct Shear and Triaxial Consolidated Undrained test on varying percentages of silt (by weight of 5%,10%,15%). These primary conclusions were obtained from this investigation. With the addition of silt there was considerable decrease in the value of angle of internal resistance and small increase in cohesion in the soil. During the design of structure, most of the cases the plain strain problem is carried out. Therefore an attempt has been carried out to establish a relation between the angle of shearing resistance obtained from Direct Shear test and Triaxial test.

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49

Wang, Po-Yen, i 王柏雁. "Calibration of Dilatometer Test in Silty Sand". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/72617733496616248741.

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碩士
國立交通大學
土木工程研究所
86
Because of the lack of cohesion, it is very difficult to obtain undisturbed samples for sand. In situ tests are often used to determine the engineering properties for sand. The Marchetti flat dilatometer test (DMT) is a popular in situ test method in Europe and Northern America. As in many other types of in situ test methods, the interpretation of DMT data is mostly empirical. The majority of the available empirical rules came from Europe or Northern America, and are based on tests in uniformly graded, clean sand. The sand on the West Coast of Taiwan, including in Mai Liao, Yuen Lin, contains significant amounts of silt. Experiments have indicated that this type of sand is compressible and crushable, and has a less tendency to dilate. The differences between a uniformly graded clean sand and a silty sand can be significant. Hence, to directly adopt the empirical DMT interpretation rules developed in the West, to the sand on the West Coast of Taiwan may be undesirable. 　　This research is part of an effort to establish the engineering characteristics for the Mai Liao silty and (MLS) that typifies the sand deposit on the West Coast of Taiwan. A series of experiments have been carried out to establish the basic physical and engineering properties of MLS. Existing experiments include calibration of cone penetration tests in MLS. This research project concentrates on DMT. The main objective of this research project is to evaluate the feasibility of the existing empirical DMT interpretation methods, and to establish new interpretation methods when necessary. Considering the effects of high fines content, relative density and lateral earth pressure, a series of DMT calibration tests have been conducted. The thesis describes the background of this research, its objectives, approach, procedures of the DMT calibration tests and their results.

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50

Wei-Shih, Wu, i 巫偉詩. "The Soil Water Characteristic Curves of Silty Sand". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/02371578132448030089.

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碩士
建國科技大學
土木與防災研究所
101
The soil water characteristic curve (SWCC) describes the relationship between saturation and water content of soil. The matric suction is affected by water content and change the shear strength. The matric suction provides additional shear strength to stabilize unsaturated soil slope in the dry season. When rainy season comes, rainfall infiltration weakens matric suction and trigger landslide. This study perform pressure plate tests to establish SWCC and SDSWCC (stress dependent soil water characteristic curve). The silty sand (Mai Liao Sand, MLS) is used to produce testing specimen according to different fines content (FC) and relative density (Dr). Test results shows FC affect the slope of descent of SWCC when applied pressure is not over 250kPa. The SWCC tends to change slowly when specimen has higher FC. The hysteresis effect (the difference of desorption and sorption at initial state) is obvious when specimen has lower FC. The difference between SWCC and SDSWCC is that SDSWCC considers the influence of vertical loading. Because of the loading effects, SDSWCC is slightly different from SWCC for silty sand. A few tests of lateritic soil are also carried out to compare with MLS. The SWCC of lateritic soil presents a more gentle descent curve in comparison with MLS.

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