Depositional processes are the most critical, complicated conditions that govern sediment properties and their variations, which in turn significantly affect the geotechnical behavior of the sediment. The complexity of depositional and post-depositional processes, which results in a variety of depositional environments, makes constructing a plausible model for the consolidation process of sediments difficult. The mutual influence between the temporal and spatial variation of depositional environments with their resultant physical and mechanical properties cause several compression issues, such as consolidation settlement and land subsidence, which mostly occur in estuarine-riverine regions throughout the world. The first aim of this study is proposing a new grain-size based scheme to classify unconsolidated inorganic sediments that cover a wide range of natural depositional environments with a special emphasis on fine-grained deposits. The proposed classification depends on the linear relationship between percent Fines and the silt fraction. By combining grain size characteristics and plasticity, the proposed scheme provides further characterization of depositional environments. The proposed scheme extends the utility of the scheme beyond simply classifying the sediment class, towards inferring the potential mechanical behavior of sediments having various Grain Size Distribution (GSD) proportions and mineralogy. Addressing elastic wave properties as a geotechnical parameter, in particular, shear wave velocities to determine the mechanical behavior of sediments is because is strongly influenced by the change in those physical state properties during compression and cementation processes. This study presents a continuous function that explicitly uses shear wave velocity to predict the non-linear function of consolidation process (e -log p'), This approach also defines factors that describe the depositional environment, such as grain size and plasticity limits. These factors are shown to influence and control the e -log p' relationship. Thus, the resulting function is shown to be applicable to a variety of sedimentary materials. Also, in this dissertation, elastic shear-wave velocity under critical state framework was employed. A shear wave-based constitutive model was developed that is able to predict the stress-strain behavior of a normally consolidated sediments, under undrained loading. A new power-type relationship that predicts the shear strength behavior and critical stress paths of fine-grained sediments under undrained conditions. Also, it investigates the reliability of the link between input model parameters with the basic properties of a variety of fine-grained sediments. As importance of measuring of elastic wave velocities, a number of soil tests performed during particular construction stages can be reduced and compensated. This reduces the cost of evaluating the stability level, monitoring stress path distributions, and determining undrained shear strength behavior during particular stages of the construction process. The study also provides correlations that can be applied in various fine-grained depositional environments that have weak, fine-grained soil layers, on which the constructions are built.

The purpose of this thesis is to gain understanding of the load on flat target surfaces produced by projectile impact. Models are proposed from which upper and lower bounds can be derived for the transition be-tween interface defeat and normal penetration. It is shown that the dominating contribution to the normal load is generally provided by the hydrodynamic pressure due to the effect of inertia. In addition it is shown that the contributions from yield strength and compressibility are also significant. For a cylindrical tungsten alloy projectile at an impact velocity representative of to-day’s ordnance velocities, the contributions to the load intensity on the axis of symmetry from yield strength and compressibility are shown to be 15% and 3.4%, respectively, of that of inertia. Impact tests have shown that for conical projectiles transition from interface defeat to penetration occurs at a significantly lower impact velocity than for cylindrical projectiles. In order to better understand the influence of projectile shape, a conical projectile in axi-symmetric impact is studied by use of an analytical model for self-similar flow, and the results obtained are compared to results of numerical simula-tions. It is shown how the maximum load intensity, and the position of the maximum, depends on the apex angle. For an apex angle of 90º, the maximum load intensity is found to be almost three times that pro-duced by a cylindrical projectile with the same impact velocity. This maximum occurs well off the axis of symmetry and is 20% larger than the load intensity at this axis. Both the self-similar model and the nu-merical simulations show that the contribution to the load intensity from compressibility is positive below and negative above an apex angle of around 80º. The contribution of yield strength to the load in-tensity at centre of impact depends only weakly on the apex angle and is therefore similar to that of a cylindrical projectile.

A new measurement technique called fiber optic reflectometer (FOR) was developed to investigate multiphase flows. The principle and setup of the FOR technique were introduced and applied to various experiments. Based on the coherently mixed signal between the Fresnel reflection off the fiber-liquid interface and the scattered signal off the object, such as a gas bubble, and a solid particle, this single probe technique is capable of simultaneously measuring the velocity of the object with a high accuracy and the phase of the fluid. In addition, bubble diameter, velocity, and void fraction were measured directly. By means of a simple modification of the FOR technique, solute concentration and refractive index change were measured with a greatly improved accuracy. This modified technique was used for measuring of a NaCl concentration in deionized water to validate a new normalization technique. In the second part of this thesis, a plunging breaking wave in deep water has been studied. Using the wave focusing method, a strong plunging breaker was generated with accuracy in the deep water condition in a two-dimensional wave tank. It was possible to describe the breaking process in detail using a high speed camera with a frame rate of 500 or 1000 fps. Four kinds of experimental techniques were employed or developed to investigate the plunging breaker. Bubble image velocimetry (BIV) and particle image velocimetry (PIV) were used to measure the velocity fields. The velocity fields of the highly aerated region were obtained from the BIV measurements. In addition, the modified PIV technique is capable of measuring the velocities in the entire flow field including the aerated region. Mean and turbulent properties were obtained by the ensemble average. The mean velocity, mean vorticity, and mean kinetic energy were examined over the entire flow field. In addition, the Reynolds stresses and turbulent kinetic energy were calculated with high temporal and spatial resolutions. Free surface elevation was obtained from wave gauge measurements. BIV and PIV images were also used to obtain the free surface elevation and the boundary of the aerated region for more accurate results. The FOR technique was used to obtain the void ratio at each splash-up region. Compressibility of the plunging breaker was considered. Mass flux, momentum flux, kinetic energy, and Reynolds stresses at each FOR station were recalculated using the void ratio obtained from the FOR measurements. All terms at the first splash-up region were highly overestimated more than 100 percent unless the void ratio was applied to the calculation of fluxes and energies. Compared with the fully developed first splash-up region, the overestimation at the second and third splash-up was less significant. However, most terms were overestimated by 20~30 percent when the void ratio was not considered.

In this research, the Alternating Cell Direction Implicit method is used in temporal discretisation of the incompressible Navier-Stokes equations and compared with the well known and widely used Point Gauss Seidel scheme on structured and quadrilateral unstructured meshes. A two dimensional, laminar and incompressible Navier-Stokes solver is developed for this purpose using the artificial compressibility formulation. The developed solver is used to obtain steady-state solutions with implicit time stepping methods and a third order data reconstruction scheme (U-MUSCL) is added to obtain high order spatial accuracy. The Alternating Cell Directions Implicit method and Point Gauss Seidel scheme is compared in terms of convergence iteration number and total computation time using test cases with growing complexity, including laminar flat plate, single and multi-element airfoil calculations. Both structured and quadrilateral unstructured grids are used in single element airfoil calculations. In these test cases, it is seen that a reduction between 13% and 20% is obtained in total computation time by usage of Alternating Cell Directions Implicit method when compared with the Point Gauss Seidel method.

Anisotropy in engineering properties of soils occurs due to the depositional process forming the soil fabric and/or different directional stresses in soil history. This study investigates the anisotropy in undrained shear strength and drained compressibility of preconsolidated, stiff and fissured Ankara Clay. The compressibility behavior is determined using standard oedometer testing while the shear strength anisotropy is investigated through large diameter unconsolidated-undrained triaxial testing on undisturbed samples taken in vertical and horizontal directions from several deep excavation sites along the Konya Road in &Ccedil / ukurambar-Balgat Area, Ankara. According to the results achieved, Ankara Clay is slightly anisotropic in compressibility, with an anisotropy ratio between 0.72 and 1.17 in terms of coefficient of volume compressibility for several pressure ranges between 50 kPa and 1600 kPa. On the other hand, while a slight anisotropy in undrained shear strength at a ratio ranging between 0.87 and 1.19 in terms of deviator stress can be observed in Ankara Clay, considering the great variation in the test results of samples in same direction which mostly overlaps with the range of results obtained in the other direction, it has been concluded that the Ankara Clay located in this area can be regarded as isotropic in terms of shear strength for practical purposes.

A mathematical model is developed for investigating time dependent surface deformations of a hydrostatic water volume, when it is subjected to a sudden partial collapse or rise of the sea bottom. The model solves two-dimensional Navier-Stokes Equations on a vertical plane numerically by using Marker and Cell Method (MAC) for viscous and compressible fluid including all the nonlinear effects in the solution. For demonstration, a vertical motion was given to a section in a hypothetical reservoir bed within a short time period and the resulting velocity and pressure fields and the surface profile of the water body are obtained. Computational and physical aspects are discussed.

ABSTRACT SIMULATION OF SURFACE WAVES GENERATED BY A RAPID RISE OF A BLOCK AT THE SEA BOTTOM SENOL, Nalan M.Sc., Department of Civil Engineering, Supervisor: Assoc. Prof. Dr. ismail AYDIN July 2005, 74 Pages A mathematical model is developed for investigating time dependent surface deformations of a hydrostatic water volume, when it is subjected to a sudden partial rise of the sea bottom. In the model, 2-dimensional, compressible, and viscous Navier-Stokes equations are solved by Marker and Cell (MAC) method. Variable mesh size in both horizontal and vertical directions with a staggered grid arrangement is used. Limited compressibility model is utilized for pressure. Various computational tests are done for the selection of computational parameters of the model. It is found that the amplitude of surface waves generated by vertical displacements of the sea bottom depends on size and speed of bottom displacements.

In this investigation, the flow friction associated with laminar pulsating flows through porous media was numerically studied. The problem is of interest for understanding the regenerators of Stirling and pulse tube cryocoolers. Two-dimensional flow in a system composed of a number of unit cells of generic porous structures was simulated using a CFD tool, with sinusoidal variations of flow with time. Detailed numerical data representing the oscillating velocity and pressure variations for five different generic porous structure geometries in the porosity range of 0.64 to 0.84, with flow pulsation frequency of 40 Hz were obtained, and special attention was paid to the phase shift characteristics between the velocity and pressure waves. Based on these detailed numerical data, the standard unsteady volume-averaged momentum conservation equation for porous media was then applied in order to obtain the instantaneous as well as cycle-averaged permeability and Forchheimer coefficients. It was found that the cycle-averaged permeability coefficients were nearly the same as those for steady flow, but the cycle-averaged Forchheimer coefficients were about two times larger than those for steady flow. Significant phase lags were observed with respect to the volume-averaged velocity and pressure waves. The parametric trends representing the dependence of these phase lags on porosity and flow Reynolds number were discussed. The phase difference between pressure and velocity waves, which is important for pulse tube cryocooling, depended strongly on porosity and flow Reynolds number.

This is an experimental study into the permeability and compressibility properties of bagasse pulp pads. Three experimental rigs were custom-built for this project. The experimental work is complemented by modelling work. Both the steady-state and dynamic behaviour of pulp pads are evaluated in the experimental and modelling components of this project. Bagasse, the fibrous residue that remains after sugar is extracted from sugarcane, is normally burnt in Australia to generate steam and electricity for the sugar factory. A study into bagasse pulp was motivated by the possibility of making highly value-added pulp products from bagasse for the financial benefit of sugarcane millers and growers. The bagasse pulp and paper industry is a multibillion dollar industry (1). Bagasse pulp could replace eucalypt pulp which is more widely used in the local production of paper products. An opportunity exists for replacing the large quantity of mainly generic paper products imported to Australia. This includes 949,000 tonnes of generic photocopier papers (2). The use of bagasse pulp for paper manufacture is the main application area of interest for this study. Bagasse contains a large quantity of short parenchyma cells called ‘pith’. Around 30% of the shortest fibres are removed from bagasse prior to pulping. Despite the ‘depithing’ operations in conventional bagasse pulp mills, a large amount of pith remains in the pulp. Amongst Australian paper producers there is a perception that the high quantity of short fibres in bagasse pulp leads to poor filtration behaviour at the wet-end of a paper machine. Bagasse pulp’s poor filtration behaviour reduces paper production rates and consequently revenue when compared to paper production using locally made eucalypt pulp. Pulp filtration can be characterised by two interacting factors; permeability and compressibility. Surprisingly, there has previously been very little rigorous investigation into neither bagasse pulp permeability nor compressibility. Only freeness testing of bagasse pulp has been published in the open literature. As a result, this study has focussed on a detailed investigation of the filtration properties of bagasse pulp pads. As part of this investigation, this study investigated three options for improving the permeability and compressibility properties of Australian bagasse pulp pads. Two options for further pre-treating depithed bagasse prior to pulping were considered. Firstly, bagasse was fractionated based on size. Two bagasse fractions were produced, ‘coarse’ and ‘medium’ bagasse fractions. Secondly, bagasse was collected after being processed on two types of juice extraction technology, i.e. from a sugar mill and from a sugar diffuser. Finally one method of post-treating the bagasse pulp was investigated. The effects of chemical additives, which are known to improve freeness, were also assessed for their effect on pulp pad permeability and compressibility. Pre-treated Australian bagasse pulp samples were compared with several benchmark pulp samples. A sample of commonly used kraft Eucalyptus globulus pulp was obtained. A sample of depithed Argentinean bagasse, which is used for commercial paper production, was also obtained. A sample of Australian bagasse which was depithed as per typical factory operations was also produced for benchmarking purposes. The steady-state pulp pad permeability and compressibility parameters were determined experimentally using two purpose-built experimental rigs. In reality, steady-state conditions do not exist on a paper machine. The permeability changes as the sheet compresses over time. Hence, a dynamic model was developed which uses the experimentally determined steady-state permeability and compressibility parameters as inputs. The filtration model was developed with a view to designing pulp processing equipment that is suitable specifically for bagasse pulp. The predicted results of the dynamic model were compared to experimental data. The effectiveness of a polymeric and microparticle chemical additives for improving the retention of short fibres and increasing the drainage rate of a bagasse pulp slurry was determined in a third purpose-built rig; a modified Dynamic Drainage Jar (DDJ). These chemical additives were then used in the making of a pulp pad, and their effect on the steady-state and dynamic permeability and compressibility of bagasse pulp pads was determined. The most important finding from this investigation was that Australian bagasse pulp was produced with higher permeability than eucalypt pulp, despite a higher overall content of short fibres. It is thought this research outcome could enable Australian paper producers to switch from eucalypt pulp to bagasse pulp without sacrificing paper machine productivity. It is thought that two factors contributed to the high permeability of the bagasse pulp pad. Firstly, thicker cell walls of the bagasse pulp fibres resulted in high fibre stiffness. Secondly, the bagasse pulp had a large proportion of fibres longer than 1.3 mm. These attributes helped to reinforce the pulp pad matrix. The steady-state permeability and compressibility parameters for the eucalypt pulp were consistent with those found by previous workers. It was also found that Australian pulp derived from the ‘coarse’ bagasse fraction had higher steady-state permeability than the ‘medium’ fraction. However, there was no difference between bagasse pulp originating from a diffuser or a mill. The bagasse pre-treatment options investigated in this study were not found to affect the steady-state compressibility parameters of a pulp pad. The dynamic filtration model was found to give predictions that were in good agreement with experimental data for pads made from samples of pretreated bagasse pulp, provided at least some pith was removed prior to pulping. Applying vacuum to a pulp slurry in the modified DDJ dramatically reduced the drainage time. At any level of vacuum, bagasse pulp benefitted from chemical additives as quantified by reduced drainage time and increased retention of short fibres. Using the modified DDJ, it was observed that under specific conditions, a benchmark depithed bagasse pulp drained more rapidly than the ‘coarse’ bagasse pulp. In steady-state permeability and compressibility experiments, the addition of chemical additives improved the pad permeability and compressibility of a benchmark bagasse pulp with a high quantity of short fibres. Importantly, this effect was not observed for the ‘coarse’ bagasse pulp. However, dynamic filtration experiments showed that there was also a small observable improvement in filtration for the ‘medium’ bagasse pulp. The mechanism of bagasse pulp pad consolidation appears to be by fibre realignment. Chemical additives assist to lubricate the consolidation process. This study was complemented by pulp physical and chemical property testing and a microscopy study. In addition to its high pulp pad permeability, ‘coarse’ bagasse pulp often (but not always) had superior physical properties than a benchmark depithed bagasse pulp.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Which the effect of no-tillage system on the soil physical and mechanical properties along the time? With this question, the objective this study was to evaluate the effect of the no-tillage system along the time on the physical and mechanical properties of the soil, as well as, the behavior of the compressive properties along the use of Oxisol Red. The experimental design used was of randomized block with bi-factorial 5 x 2, with five different times of implantation management and two levels of traffic. The implantation times of the no-tillage used were: SD0 - 0 years (2 months); SD2 - 2 years; SD4 - 4 years; SD5.5 5.5 years and SD14 - 14 years. The level of traffic was without and with traffic. Soil samples were collected in three layers: 0.0 0.06 m, 0.07 0.14 m and 0,15 0.22 m. The SD0 demonstrated increase macroporosity that resulted in high saturated hydraulic conductivity thus increased the air permeability, in all the soil layers studied. With the increase of the time implantation of the no-tillage system, increased of microporosity and organic carbon, in the layer 0.00 0.06 m. The SD5.5 and SD14 was the treatments that retain more water independently of the traffic from machines. In the beginning of the no-tillage system had a smaller bulk density and occurrence of larger relative deformations, while after some years, there are an elevation of the bulk density and the reduction of deformation that extends until the fifth and a half year, where, there is a reduction of the bulk density and deformation to the 14th year. The traffic doesn't generate enough differences in the compression index, pré-consolidation tension, bulk density and the degree of water saturation that soil to 33 kPa. In the 0.07 0.14 m of soil, occurred an elevation of the bulk density and reduction of the avoid ratio independently of the time implantation of no-tillage. The degree of water saturation influenced the deformation until the 5th and a half year of use of no-tillage, after that, action of the structure reduced your effect in the soil. / Qual o efeito do sistema plantio direto nas propriedades físico-mecanicas ao longo do tempo? com essa questão, o objetivo deste estudo foi avaliar o efeito do sistema plantio direto ao longo do tempo nas propriedades físico-mecanicas do solo, bem como, o comportamento das propriedades compressivas ao longo do uso de um Latossolo Vermelho distrófico. Os tratamentos foram distribuídos em blocos ao acaso em esquema bi-fatorial 5x2, possuindo cinco diferentes tempos de implantação do sistema plantio direto e dois níveis de tráfego. Os tempos de implantação do sistema plantio direto usados foram: SD0 0 anos (2 meses); SD2 2 anos; SD4 4 anos; SD5.5 5,5 anos e SD14 14 anos. Os níveis de tráfego eram sem e com tráfego. Foram coletadas amostras de solo em três camadas: 0,0-0,06 m, 0,07-0,14 m e 0,15-0,22 m. O SD0 apresentou elevada macroporosidade o que resultou numa elevada condutividade hidráulica do solo saturado, proporcionando maior condutividade ao ar, em todas as camadas de solo estudadas. O aumento do tempo de implantação do sistema plantio direto aumentou a microporosidade e o teor de carbono orgânico, na camada 0,00 0,06 m. O SD5.5 e SD14 foram os tratamentos que retiveram mais água independentemente do tráfego de máquinas. No início do sistema plantio direto houve uma menor densidade do solo e ocorrência de maiores deformações relativas, e, após alguns anos, houve uma elevação da densidade e redução da deformação que se estende até o quinto ano e meio, onde há novamente uma redução da densidade e da deformação até o 14º ano. O tráfego não gerau diferença suficiente no coeficiente de compressão, tensão de pré-consolidação, densidade do solo e no grau de saturação inicial desse solo a 33 kPa. Nos 0,07 0,14 m de solo houve uma elevação da densidade do solo e redução do índice de vazios independente do tempo de implantação do sistema plantio direto. O grau de saturação inicial possuiu influência na deformação até o 5º ano e meio de uso de sistema plantio direto, após isso, ação do manejo à estrutura reduziu o seu efeito no solo.