Two different soils may be generated from open-pit mining: lumpy soils with a granular structure and clay mixtures, depending on the length of the conveyor belt and the strength of the original soils. Lumpy soils may be created for a high strength of the excavated soils. They are dumped as landfills without any compaction, which permits the water and air flows via the inter-lump voids. As a result, a new structure consisting of the lumps and reconstituted soil within the inter-lump voids can be created. However, if the original soil has a low strength or a long transportation takes place, the material may disintegrate into small lumps and thoroughly mix soils from different layers. Landfills consisting of clay mixtures arise in this way. The stability and deformation of landfills are crucial for design of occupied area and landfill slopes. For this reason, three different landfill materials will be investigated in this thesis: (1) the lumpy granular soil from fresh landfills, (2) the lumpy composite soil corresponding to old landfills and (3) clay mixtures. Firstly, an artificial lumpy soil was investigated. It is a transition form between the reconstituted and natural lumpy soils. Compression, permeability and strength of lumpy materials have been evaluated based on oedometer and triaxial tests. The shear strength of the normally consolidated lumpy specimens lies approximately on the Critical State Line of the reconstituted soil. The reconstituted soil, which exists in the inter-lump voids, plays a crucial role in the behaviour of artificial lumpy materials. Similarly to the artificial lumpy soil, inter-lump voids of the natural lumpy soil are mainly closed above a relatively small stress level, which is induced by the rearrangement of the lumps. However, its limit stress state is located above the Critical State Line of the reconstituted soil, which may be caused by the diagenetic soil structure in the natural lumps. The structure transition of the lumpy granular material can be divided into three possible stages related to the stress level. Firstly, the compressibility of a fresh lumpy is relativity high due to the closure of the inter-lump voids within a low stress range. In this stage, the hydraulic conductivity is mainly controlled by the inter-lump skeleton due to the existence of macro drainage paths, while the shear strength is controlled by the reconstituted soil around the lumps. Afterwards, its compressibility decreases with the consolidation stress and the soil behaves similarly to an overconsolidated soil. The clayfill appears to be uniform visually in this stage, but its structure is still highly heterogeneous and the hydraulic conductivity is higher than that of the reconstituted soil with the same overall specific volume. Finally, the loading reaches the preconsolidation stress of the lumps, and the whole soil volume becomes normally consolidated. Isotropically consolidated drained triaxial shear tests were performed on artificially prepared specimens with parallel and series structures. The laboratory tests show that the specimens with the series structure have the same failure mode as the constituent with the lower strength; the specimens with the parallel structure have a failure plane which crosses both constituents. As a result, the shear strength of the series specimens is only slightly higher than that of the constituent with the lower strength and the strength of the parallel specimens lies between those of the constituents. Afterwards, the behaviour of an artificial lumpy material with randomly distributed inclusions is investigated using the Finite Element Method. The computation results show that the stress ratio, defined as the ratio of the volume-average stress between the lumps and the reconstituted soil within the inter-lump voids, is significantly affected by both the volume fraction and the preconsolidation pressure of the lumps under an isotropic compression path, while the volume fraction of the lumps plays a minor role under a triaxial compression path. Based on the simulation results and analysis of the two basic configurations, a homogenization law was proposed utilizing the secant stiffnesses. The compression behavior of the lumpy composite soil was analyzed within the homogenization framework. Firstly, the volume of the composite soil was divided into four individual components. The inter-lump porosity was introduced to account for the evolution of the volume fractions of the constituents, and it was formulated as a function of the overall porosity and those of its constituents. A homogenization law was then proposed based on the analysis of the lumpy structure together with a numerical method, which gives a relationship for tangent stiffnesses of the lumpy soil and its constituents. Finally, a simple compression model was proposed for the composite lumpy material, which incorporates both the influence of the soil structure and the volume fraction change of the reconstituted soil. Furthermore, a general framework for the consolidation behaviour of the lumpy composite soil was proposed based on the double porosity concept and the homogenization theory. To describe the behaviour of lumps with low stress level, a new failure line was proposed with help of the equivalent Hvorslev pressure and critical state concept. The structure effect was incorporated into the nonlinear Hvorslev surface within sensitivity framework and the generalized Cam clay model proposed by McDowell and Hau (2003) was adopted on the wet side of the critical state. A secant stiffness, defined as the ratio between the deviatoric stress and deviatoric strain, was used in the homogenization law. Finally, a simple model for the natural lumpy soil was proposed within the homogenization framework. The physical properties, compression behaviour and remolded undrained shear strength of clay mixtures were investigated by reproducing the soils artificially in the lab. Afterwards, the models for the compression and undrained shear strength of clay mixtures were proposed. The model for the strength of the clay mixture originated from simplifying the structure of a clay mixture, in which the elements of the constituents are randomly distributed in a representative elementary volume. By defining a water content ratio (the ratio of water contents between the constituents), the undrained shear strength of each constituent was estimated separately and then combined together with corresponding volume fractions. A homogenization law was proposed afterwards based on the analysis of the randomly arranged structure. A simple compression model considering $N$ constituents was proposed within the homogenization framework, which was evaluated by a mixture with two constituents.:1 Introduction 1.1 General 1.2 Lumpy soils as landfills 1.3 Clay mixtures as landfills 1.4 Objectives of this work 1.4.1 Lumpy granular structure 1.4.2 Lumpy composite structure 1.4.3 Clay mixtures 1.5 Structure of this study 2 Literature review 2.1 Fresh-lumpy soils 2.1.1 Structure of fresh-lumpy soils 2.1.2 Mechanical behaviour of fresh lumpy soils 2.2 Lumpy composite soils 2.2.1 Basic theory of inhomogeneous soils 2.2.2 Mechanical properties of stiff lumps with low stress level 2.2.3 Numerical and theoretical investigation 2.2.4 Consolidation behaviour of lumpy soils 3 Laboratory investigation of artificial lumpy materials 3.1 Introduction 3.2 Material properties and preparation of lumpy sample 3.3 Test procedures 3.3.1 Triaxial tests 3.3.2 Oedometer tests 3.4 Initial specific volume 3.5 Behaviour of the reconstituted soil 3.6 Behaviour of the lumpy material 3.6.1 Isotropic compression 3.6.2 Oedometer tests 3.6.3 Error analysis of the initial specific volume 3.6.4 Shear strength 3.6.5 Structure transition of lumpy material 3.7 Conclusions 4 Laboratory investigation of a natural lumpy soil 4.1 Introduction 4.2 Material properties and preparation of lumpy sample 4.3 Analysis of the test results 4.3.1 Reconstituted soil 4.3.2 Natural soil 4.3.3 Natural lumpy soil 4.3.4 Discussions on the shear strength of natural lumpy soil 4.4 Conclusions 5 Structure transition of lumpy materials 5.1 Introduction 5.2 Experimental investigation 5.2.1 Material properties and preparation of lumpy samples 5.2.2 Test results and data from literature 5.2.3 Structure transition of the lumpy material in oedometer test 5.2.4 Evolution of inter-lump voids of fresh lumpy soils 5.3 Interpretation of the structure transition of clayfills in the field 5.4 Conclusions 6 Two basic configurations for inhomogeneous soils 6.1 Introduction 6.2 Materials and sample preparation 6.3 Homogeneous soil 6.4 Inhomogeneous samples 6.5 Comparison between inhomogeneous and homogeneous samples 6.6 Numerical homogenization 6.7 Model application 6.8 Conclusions 7 Numerical simulation of lumpy composite soils 113 7.1 Introduction 7.2 Multiparticle generation and model calibration 7.2.1 Geometric model 7.2.2 Constitutive model for the constituents and its calibration 7.3 Numerical simulations 7.3.1 Stress distribution 7.4 A homogenization law for the stiffness of lumpy soils 7.4.1 One-dimensional model 7.4.2 General model 7.5 Homogenization law using the tangent stiffnesses under isotropic compression load 7.6 Conclusion 8 Compression behaviour of lumpy composite materials 8.1 Introduction 8.2 Experimental investigation 8.2.1 Material properties and preparation of lumpy sample 8.2.2 Test results 8.3 A compression model for lumpy soils 8.3.1 Volume divisions 8.3.2 Definitions of stresses and strains 8.3.3 Constitutive equations for the constituents 8.3.4 A homogenization law for the tangent stiffness of lumpy composite soil 8.3.5 Compression model for the lumpy composite soil 8.4 Application of the model to experimental data 8.4.1 Model parameters 8.4.2 Simulation of oedometric compression 8.4.3 Evaluation of model predictions 8.4.4 An improvement of the model 8.5 Conclusions 9 Consolidation behaviour of lumpy composite soils 9.1 Introduction 9.2 Basic components for the model 9.2.1 Volume groups of the lumpy soil 9.2.2 Stress and strain distributions for the lumpy soil 9.2.3 Permeability properties of the constituents 9.3 Derivation of the governing equations 9.3.1 Mass balance equations 9.3.2 Equilibrium differential equation 9.3.3 Simplification of the model 9.4 Finite element analysis 9.5 Model parameters and sensitivity analysis 9.6 Model evaluation 9.7 Conclusions 10 A double logarithmic Hvorslev surface 10.1 Introduction 10.2 Laboratory investigations 10.2.1 Material and test procedures 10.2.2 Test results and analysis 10.3 Double logarithmic Hvorslev surface 10.4 Full constitutive model 10.4.1 Elastic behaviour 10.4.2 The yield and plastic potential surfaces 10.4.3 Hardening parameter 10.5 Analysis of the model and its evaluation 10.5.1 Model parameters 10.5.2 Evaluation of the model 10.6 Conclusions 11 A simple model for natural lumpy composite soils 11.1 Introduction 11.2 Lumpy soil as a composite material 11.2.1 Volume fraction of reconstituted soil in lumpy composite soils 11.2.2 Definitions of stresses and strains 11.3 Constitutive equations for the constituents 11.3.1 Elastic behaviour 11.3.2 Hvorslev surface incorporating structure effect 11.3.3 Yield and Potential surfaces for natural lumps 11.3.4 Hardening rule and full constitutive model for natural lumps 11.3.5 Simplification of the model 11.4 Proposed model for lumpy composite soils 11.4.1 A homogenization law for lumpy composite soil 11.4.2 General model 11.5 Application of the model 11.5.1 Evaluation of nonlinear Hvorslev surface for natural stiff soils 11.5.2 Laboratory investigations of a natural lumpy soil 11.5.3 Model parameters 11.5.4 Model procedures 11.5.5 Model evaluations 11.6 Conclusions 12 Compression and undrained shear strength of remolded clay mixtures 12.1 Introduction 12.2 Materials and sample preparation 12.3 Compression behaviour of the mixed soil 12.4 Remolded shear strength of the clay mixtures 12.5 Conclusions 13 Undrained shear strength and water content distribution 13.1 Introduction 13.2 Structure of a clay mixture 13.3 Proposed model 13.3.1 Water content distribution 13.3.2 Undrained shear strength and liquid limit of a clay mixture 13.4 Model evaluation 14 Compression behaviour of remolded clay mixtures 14.1 Introduction 14.2 Initial water content distribution 14.3 Volume fractions and stress ratios of the constituents 14.4 Reference model for the constituents 14.4.1 A homogenization law for the tangent stiffness of the clay mixtures 14.4.2 Compression model for the clay mixtures 14.5 Validation of the proposed model 14.5.1 Model parameters 14.5.2 Simulation procedure 14.5.3 Evaluation of the model 14.6 Sensitivity analysis 14.7 Summary and conclusions 15 Summary and recommendations 15.1 Lumpy granular soils 15.2 Lumpy composite soils 15.3 Clay mixtures 15.4 Outlook and recommendations Bibliography Notations Appendices A Shear strength of the series specimens A.1 Considering the influence of the shear plane A.2 Considering the influence of nonuniform deformation B Compression curves of soil mixtures / In einem Tagebau können die feinkörnigen Böden in unterschiedlichen Zustandsformen entstehen. Dies sind zum einen klumpige Böden mit einer granular ähnlichen Struktur (Pseudokornstruktur) und einer hohen Konsistenzzahl und zum anderen Mischungen aus mehreren Tonen oder Schluffen mit niedriger Konsistenzzahl. Der Zustand wird dabei massgebend von dem Transport (z.B. Länge des Förderbandes) und dem Ausgangszustand (z.B. der Anfangsscherfestigkeit) beeinflusst. Klumpige Böden entstehen bei der Abbaggerung des natürlichen Materials auf der Abbauseite, welches eine hohe Festigkeit besitzt. Alle Böden werden normalerweise ohne Verdichtung verkippt, so entstehen bei der Verkippung von klumpigen Böden grosse Makro-Porenräume zwischen den Klumpen, welche sehr luft- bzw. wasserdurchlässig sind. Nach einiger Zeit entsteht eine neue Struktur aus den Klumpen und dem Material des sich von aussen auflösenden Klumpens, welches das Füllmaterial bildet. Wenn die Festigkeit des Ausgangsmaterials niedrig ist oder lange Transportwege stattfinden, zerfallen die Klumpen. Zudem werden die Böden von verschiedenen Schichten der Abbauseite unter einander gemischt, wodurch die Tongemische entstehen. Sowohl für die Dimensionierung und Berechnung der aus den Verkippungen entstehenden Tagebaurandböschungen sowie für eine spätere Nutzung des ehemaligen Tagebaugebietes ist die Kenntnisüber das Deformations- und Verformungsverhalten von Kippenböden notwendig. Daher wurden in dieser Arbeit Tagebauböden und ihr zeitlich veränderliches Verhalten untersucht. Dabei werden diese, bezugnehmend auf den Anfangszustand, in drei typische Materialien unterschieden: (1) der frisch verkippte klumpige Boden, (2) eine Mischung aus Klumpen und Füllmaterial, welche höhere Liegezeiten repräsentiert und (3) Mischungen von feinkörnigen Ausgangsböden. Zunächst wurden künstlich hergestellte klumpige Böden untersucht. Sie bilden eine Übergangsform zwischen aufbereiteten und natürlichen klumpigen Böden. Das Kompressions- und Scherverhalten sowie die Durchlässigkeit wurden an Ödometer und Triaxialversuchen bestimmt. Das Füllmaterial, welches die Makroporen zwischen den Klumpen füllt, spielt eine entscheidende Rolle für das Materialverhalten. Ähnlich wie bei den künstlich hergestellten klumpigen Böden schliessen sich auch bei den Böden im Tagebau die Makroporenschen bei niedrigen Spannungen. Dabei werden die Klumpen umgelagert. Allerdings befindet sich die Grenze des Spannungszustandes oberhalb der Critical State Line des Füllmaterials, was möglicherweise mit den unter Diagenese entstandenen Bodenstrukturen erklärt werden kann. Die Strukturänderung der klumpigen Böden kann aufgrund des Spannungsniveaus in drei mögliche Stufen unterteilt werden. Am Anfang ist die Kompressibilität der frischen verkippten Klumpen hoch, da sich die Makroporen bereits bei geringen Spannungen schliessen. Zu diesem Zeitpunkt sind auch die Durchlässigkeiten in erster Linie von den grossen Porenräumen der Makroporen, welche als Entwässerungspfade dienen, beeinflusst. Die Scherfestigkeit hingegen, wird durch die aufgeweichten Böden an den Oberflächen der Klumpen massgebend beeinflusst. Bei höheren Konsolidationspannungen sinkt die Kompressibilität und der Boden verhält sich wie einüberkonsolidierter Boden. Obwohl die Struktur aufgrund der veränderten Klumpenoberflächen zu diesem Zeitpunkt homogener wirkt, ist die Struktur noch heterogen und die Durchlässigkeit ist höher als bei einem aufbereiteten Boden mit gleichem spezifischem Volumen (Porenzahl). Letztendlich erreicht der aktuelle Spannungszustand den derüberkonsolidierten Klumpen und der gesamte Boden verhält sich wie ein normal konsolidierter Boden. Des Weiteren wurden isotrop konsolidierte drainierte Triaxialversuche an künstlich aus zwei Ausgangsmaterialien hergestellten Proben mit parallelen und seriellen Strukturen durchgeführt. Die Laborversuche zeigten, dass die Proben mit seriellem Aufbau dieselben Gleitflächen haben, wie der Ausgangsboden mit der niedrigeren Scherfestigkeit. Die Gleitfläche der Proben mit parallelen Strukturen verlief durch beide Materialien. Es wurde festgestellt, dass die Scherfestigkeit der seriell aufgebauten Proben geringfügig höher, als die des Bodens mit der niedrigeren Scherfestigkeit ist. Die Scherfestigkeit der parallel aufgebauten Proben liegt zwischen den beiden Ausgangsmaterialien. Danach wurde das Verhalten der künstlich erzeugten klumpigen Böden mit zufällig verteiltem Füllmaterial mit Hilfe der Finiten Elemente Methode verglichen. Die Simulationen zeigten, dass unter einer isotropen Kompressionsbelastung das Spannungsverhältnis, definiert aus dem Verhältnis der Spannung des Volumendurchschnitts zwischen den Klumpen und dem Füllmaterial, deutlich durch die Volumenanteile und die Vorkonsoliderungsspannung der Klumpen beeinflusst wird. Während das Volumenverhältnis eine untergeordnete Rolle in den in Triaxialzellen unter Scherung belasteten Proben spielt. Aus den Simulationsergebnissen und den Laborversuchen der beiden Grundkonfigurationen wurde ein Homogenisierungsgesetz abgeleitet, welches die Sekandensteifigkeiten verwendet. Das Kompressionsverhalten der Mischungen aus Klumpen und Füllmaterial wurde mit Blick auf die Homogenisierung analysiert. Zunächst kann das Volumen der Mischungen in 4 individuelle Komponentenanteile zerlegt werden. Die Makroporosität zwischen den Klumpen wurde zur Entwicklung der Volumenanteile des Füllmaterials eingeführt. Sie wurde als eine Funktion der totalen Porosität und der Materialien formuliert. Auf Grundlage einer theoretischen Analyse an klumpigen Böden und unter Zuhilfenahme einer numerischen Methode wird ein Gesetz zur Homogenisierung vorgeschlagen. Dieses enthält eine Beziehung zwischen der Tagentensteifigkeit der Klumpen und seinem Füllmaterial. Abschliessend wird ein einfaches Kompressionsmodel für die Mischung aus Klumpen und Füllmaterial vorgeschlagen, welches den Einfluss der Bodenstruktur und der Änderung des Volumenanteils des Füllmaterials berücksichtigt. Darüber hinaus wurde eine allgemeine Formulierung für das Konsolidationsverhalten der klumpigen Böden mit Füllmaterial vorgeschlagen, welche sich auf das Konzept der doppelten Porosität (Klumpen und Füllmaterial) und eine Homogenisierungstheoerie bezieht. Um das Verhalten der Klumpen bei niedrigen Spannungen zu beschreiben, wird eine neue Grenzbedingung unter Zuhilfenahme der äquivalenten Hvorslev-Spannung und des Criticial State Konzeptes vorgeschlagen. Der Struktureffekt für sensitive Böden wurde in die nichtlineare Hvorslev-Oberfläche eingebaut. Das allgemein gültige Cam-Clay-Model von McDowell und Hau (2003) wurde um die nasse Seite des Critical State Konzeptes erweitert. Eine Sekandensteifigkeit, definiert aus dem Verhältnis zwischen der Deviatorspannung und der Deviatordehnung, wurde für das Homogenisieurungsgesetz ebenfalls verwendet. Abschliessend wird ein Modell für natürliche klumpige Böden vorgestellt, welches auch eine Homogenisierung beinhaltet. Die physikalischen Eigenschaften, das Kompressionsverhalten und die undrainierten Scherfestigkeiten von aufbereiten Tongemischen wurden im Labor unter Herstellung künstlicher Bödengemische untersucht. Anschliessend wurde ein Kompressions- und Schermodell für aufbereitete Tongemische vorgeschlagen. Das Modell der Scherfestigkeit der Tongemische entstand aus der Vereinfachung der Tongemischstruktur, in welcher die Elemente der Ausgangsmaterialien zufällig in dem Einheitsvolumen verteilt sind. Werden Wassergehaltsverhältnisse (das Verhältnis der Wassergehalte der Ausgangsmaterialien) definiert, kann die undrainierte Scherfestigkeit für alle Bestandteile separat geschätzt werden und dannüber die Volumenanteile bestimmt werden. Ein Homogenisierungsgesetz wurde auf Grundlage der theoretischen Analyse von zufällig angeordneten Strukturen entwickelt. Ein einfaches Kompressionsmodell, welches N-Ausgangsmaterielien bzw. Tone und eine Homogenisierung enthält, wird vorgeschlagen, und an einer Mischung aus 2 Bestandteilen im Labor validiert.:1 Introduction 1.1 General 1.2 Lumpy soils as landfills 1.3 Clay mixtures as landfills 1.4 Objectives of this work 1.4.1 Lumpy granular structure 1.4.2 Lumpy composite structure 1.4.3 Clay mixtures 1.5 Structure of this study 2 Literature review 2.1 Fresh-lumpy soils 2.1.1 Structure of fresh-lumpy soils 2.1.2 Mechanical behaviour of fresh lumpy soils 2.2 Lumpy composite soils 2.2.1 Basic theory of inhomogeneous soils 2.2.2 Mechanical properties of stiff lumps with low stress level 2.2.3 Numerical and theoretical investigation 2.2.4 Consolidation behaviour of lumpy soils 3 Laboratory investigation of artificial lumpy materials 3.1 Introduction 3.2 Material properties and preparation of lumpy sample 3.3 Test procedures 3.3.1 Triaxial tests 3.3.2 Oedometer tests 3.4 Initial specific volume 3.5 Behaviour of the reconstituted soil 3.6 Behaviour of the lumpy material 3.6.1 Isotropic compression 3.6.2 Oedometer tests 3.6.3 Error analysis of the initial specific volume 3.6.4 Shear strength 3.6.5 Structure transition of lumpy material 3.7 Conclusions 4 Laboratory investigation of a natural lumpy soil 4.1 Introduction 4.2 Material properties and preparation of lumpy sample 4.3 Analysis of the test results 4.3.1 Reconstituted soil 4.3.2 Natural soil 4.3.3 Natural lumpy soil 4.3.4 Discussions on the shear strength of natural lumpy soil 4.4 Conclusions 5 Structure transition of lumpy materials 5.1 Introduction 5.2 Experimental investigation 5.2.1 Material properties and preparation of lumpy samples 5.2.2 Test results and data from literature 5.2.3 Structure transition of the lumpy material in oedometer test 5.2.4 Evolution of inter-lump voids of fresh lumpy soils 5.3 Interpretation of the structure transition of clayfills in the field 5.4 Conclusions 6 Two basic configurations for inhomogeneous soils 6.1 Introduction 6.2 Materials and sample preparation 6.3 Homogeneous soil 6.4 Inhomogeneous samples 6.5 Comparison between inhomogeneous and homogeneous samples 6.6 Numerical homogenization 6.7 Model application 6.8 Conclusions 7 Numerical simulation of lumpy composite soils 113 7.1 Introduction 7.2 Multiparticle generation and model calibration 7.2.1 Geometric model 7.2.2 Constitutive model for the constituents and its calibration 7.3 Numerical simulations 7.3.1 Stress distribution 7.4 A homogenization law for the stiffness of lumpy soils 7.4.1 One-dimensional model 7.4.2 General model 7.5 Homogenization law using the tangent stiffnesses under isotropic compression load 7.6 Conclusion 8 Compression behaviour of lumpy composite materials 8.1 Introduction 8.2 Experimental investigation 8.2.1 Material properties and preparation of lumpy sample 8.2.2 Test results 8.3 A compression model for lumpy soils 8.3.1 Volume divisions 8.3.2 Definitions of stresses and strains 8.3.3 Constitutive equations for the constituents 8.3.4 A homogenization law for the tangent stiffness of lumpy composite soil 8.3.5 Compression model for the lumpy composite soil 8.4 Application of the model to experimental data 8.4.1 Model parameters 8.4.2 Simulation of oedometric compression 8.4.3 Evaluation of model predictions 8.4.4 An improvement of the model 8.5 Conclusions 9 Consolidation behaviour of lumpy composite soils 9.1 Introduction 9.2 Basic components for the model 9.2.1 Volume groups of the lumpy soil 9.2.2 Stress and strain distributions for the lumpy soil 9.2.3 Permeability properties of the constituents 9.3 Derivation of the governing equations 9.3.1 Mass balance equations 9.3.2 Equilibrium differential equation 9.3.3 Simplification of the model 9.4 Finite element analysis 9.5 Model parameters and sensitivity analysis 9.6 Model evaluation 9.7 Conclusions 10 A double logarithmic Hvorslev surface 10.1 Introduction 10.2 Laboratory investigations 10.2.1 Material and test procedures 10.2.2 Test results and analysis 10.3 Double logarithmic Hvorslev surface 10.4 Full constitutive model 10.4.1 Elastic behaviour 10.4.2 The yield and plastic potential surfaces 10.4.3 Hardening parameter 10.5 Analysis of the model and its evaluation 10.5.1 Model parameters 10.5.2 Evaluation of the model 10.6 Conclusions 11 A simple model for natural lumpy composite soils 11.1 Introduction 11.2 Lumpy soil as a composite material 11.2.1 Volume fraction of reconstituted soil in lumpy composite soils 11.2.2 Definitions of stresses and strains 11.3 Constitutive equations for the constituents 11.3.1 Elastic behaviour 11.3.2 Hvorslev surface incorporating structure effect 11.3.3 Yield and Potential surfaces for natural lumps 11.3.4 Hardening rule and full constitutive model for natural lumps 11.3.5 Simplification of the model 11.4 Proposed model for lumpy composite soils 11.4.1 A homogenization law for lumpy composite soil 11.4.2 General model 11.5 Application of the model 11.5.1 Evaluation of nonlinear Hvorslev surface for natural stiff soils 11.5.2 Laboratory investigations of a natural lumpy soil 11.5.3 Model parameters 11.5.4 Model procedures 11.5.5 Model evaluations 11.6 Conclusions 12 Compression and undrained shear strength of remolded clay mixtures 12.1 Introduction 12.2 Materials and sample preparation 12.3 Compression behaviour of the mixed soil 12.4 Remolded shear strength of the clay mixtures 12.5 Conclusions 13 Undrained shear strength and water content distribution 13.1 Introduction 13.2 Structure of a clay mixture 13.3 Proposed model 13.3.1 Water content distribution 13.3.2 Undrained shear strength and liquid limit of a clay mixture 13.4 Model evaluation 14 Compression behaviour of remolded clay mixtures 14.1 Introduction 14.2 Initial water content distribution 14.3 Volume fractions and stress ratios of the constituents 14.4 Reference model for the constituents 14.4.1 A homogenization law for the tangent stiffness of the clay mixtures 14.4.2 Compression model for the clay mixtures 14.5 Validation of the proposed model 14.5.1 Model parameters 14.5.2 Simulation procedure 14.5.3 Evaluation of the model 14.6 Sensitivity analysis 14.7 Summary and conclusions 15 Summary and recommendations 15.1 Lumpy granular soils 15.2 Lumpy composite soils 15.3 Clay mixtures 15.4 Outlook and recommendations Bibliography Notations Appendices A Shear strength of the series specimens A.1 Considering the influence of the shear plane A.2 Considering the influence of nonuniform deformation B Compression curves of soil mixtures

A mathematical model of two-phase systems, such as clay suspensions, consists of a set of partial differential equations which reflect both the general laws of mechanics and the relations connecting the involved characteristics of the particular system under consideration. The latter equations are known as constitutive relations. The aim of this study was to find the constitutive relations for kaolin suspensions that are necessary when solving forward problems of fine sludge thickening processes. The task was to design and carry out experimental research of the given suspension and to find a convenient method of utilizing the results for the sake of getting the sought relationships. It follows from the applied mathematical theory of two-phase systems that the sought relationships are hydraulic conductivity of the suspension as a function of the solid-phase concentration and the dependence of the solid-phase concentration on the solid-phase stress. The first part of this study describes the experimental research. Since both the characteristics are difficult to measure, it was necessary to analyze the suspension's characteristics and their measurability. Subsequently, the process of the suspension preparation and the method of laboratory measurements were determined. The following sections present...

No / The effect of matrix polymer and filler content on the rheological behavior of hydroxyapatite-filled injection molding grade high-density polyethylene (HDPE) has been studied. Studies of the flow curves revealed that the matrix and the composite exhibit three distinct regions in the flow curve, namely, a pseudoplastic region at low to moderate shear rates, a plateau and a second pseudoplastic region at high shear rates. The shear stress corresponding to the plateau (Tc) is dependent on both the filler concentration and the melt temperature. Addition of HA in the HDPE matrix increases the value of Tc and decreases compressibility of the melt. An increase in temperature also raises the value of Tc. From the nature of flow curves it is concluded that the matrix polymer largely decides the rheology of the composite.

A study was conducted to evaluate the properties and processes influencing the rate and magnitude of volume decrease and strength gain for oil sand fine tailings resulting from a change in bitumen extraction process (caustic versus non-caustic) and the effect of adding a coagulant to caustic fine tailings. Laboratory flume deposition tests were carried out with the objective to hydraulically deposit oil sand tailings and compare the effects of extraction processes on the nature of beach deposits in terms of geometry, particle size distribution, and density. A good correlation exists between flume deposition tests results using oil sand tailings and the various other tailings materials. These comparisons show the reliability and effectiveness of flume deposition tests in terms of establishing general relationships and can serve as a guide to predict beach slopes. Fine tailings were collected from the various flume tests and a comprehensive description of physical and chemical characteristics of the different fine tailings was carried out. The characteristics of the fine tailings is presented in terms of index properties, mineralogy, specific surface area, water chemistry, liquid limits, particle size distribution and structure. The influence of these fundamental properties on the compressibility, hydraulic conductivity and shear strength properties of the fine tailings was assessed. Fourteen two meter and one meter high standpipe tests were instrumented to monitor the rate and magnitude of self-weight consolidation of the different fine tailings materials. Consolidation tests using slurry consolidometers were carried out to determine consolidation properties, namely compressibility and hydraulic conductivity, as well as the effect of adding a coagulant (calcium sulphate [CaSO4]) to caustic fine tailings. The thixotropic strength of the fine tailings was examined by measuring shear strength over time using a vane shear apparatus. A difference in water chemistry during bitumen extraction was concluded to be the cause of substantial differences in particle size distributions and degree of dispersion of the comparable caustic and non-caustic fine tailings. The degree of dispersion was consistent with predictions for dispersed clays established by the sodium adsorption ratio (SAR) values for these materials. The biggest advantage of non-caustic fine tailings and treating caustic fine tailings with coagulant is an increased initial settlement rate and slightly increased hydraulic conductivity at higher void ratios. Thereafter, compressibility and hydraulic conductivity are governed by effective stress. The chemical characteristics of fine tailings (water chemistry, degree of dispersion) do not have a significant impact on their compressibility behaviour and have only a small influence at high void ratio (low effective stress). Fine tailings from a caustic based extraction process had relatively higher shear strengths than comparable non-caustic fine tailings at equivalent void ratios. However, shear strength differences were small and the overall impact on consolidation behaviour, which also depends on compressibility and hydraulic conductivity, is not expected to be significant.

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No description available.

Clays are used for long for the control of soil and water pollution as they are inexpensive natural materials with a high adsorption capacity for a wide range of pollutants. However their use as components in engineered waste containment systems is often limited when it comes to the control of organic contaminants as the clays are organophobic in nature. Organic modification of the natural clays, by replacing the exchangeable inorganic cations of clay with organic cations, can facilitate to overcome this limitation. On modification the clays become organophilic which can enhance their sorption capacities for organic contaminants. There are several ways by which natural clays can be modified with organic cations. The type of clay, the type of modifier, and the extent of modification play an important role in enhancing the organic sorption capacity. Sorption of organics by the organo clays depends on a large extent on the specific interactions that occur between modified clay and the organic contaminants. The interaction between the clay and the contaminants depend on the physico-chemical properties of modified clay and nature of organic contaminants. Since the properties of natural clays are likely to be altered by the modification a detailed study has been taken up to understand the physico chemical characteristics of organo clays which essentially control their organic sorption efficiency. Apart from bentonite which is widely used as a component of barrier systems, the characteristics of other types of clays on organic modification also needs to be assessed as they can also form part of the containment system frequently. Further the modification of clays is bound to bring in significant changes on their geotechnical properties which may affect their performance when used as barrier material. Only limited research has been conducted in the past on the geotechnical characteristics of organo clay. Therefore extensive studies have been carried out on the evaluation of the geotechnical characteristics of organo clays and the effect of organic modification on important geotechnical properties. Since very often inorganic and organic contaminants can occur simultaneously, admixtures of bentonite and organically modified clays needs to be employed as a part of clay barrier system. Moreover clay alone is very rarely used as component of barrier systems and significant portion of barrier material usually include non clay fraction. Hence studies have been carried out on mixtures containing different proportions of organo clay and bentonite and sand – organo clay / bentonite to evaluate their geotechnical behavior. Important geotechnical properties considered for detailed studies are swelling, compressibility and permeability. Detailed studies on the organic sorption capacities of different organically modified and unmodified clays, mixtures of bentonite and organo clays have also been conducted. The results of studies conducted are presented in 9 chapters. The organization of the thesis is as follows: Chapter 1 gives detailed background information on the sources and hazards of organic contaminants, inadequacy of conventional barriers to contain organic contaminants, the need for modification of natural clays, and the methods for organic modification of clays. Extensive review of literature has highlighted the need to study the effect of organic modification on the physico chemical and geotechnical properties of clay in different pore fluids. Organo clays were prepared using a wide range of clays viz., two types of bentonites of different regions, black cotton clay and commercially available kaolinite with a long chain organic cation. The extent of organic modification was varied by varying the amount of organic cation exchanged as function of total cation exchange capacity of the clays. Detailed physico chemical characterization of these modified and unmodified clays has been carried out with the help of different state of art techniques. The Chapter 2 brings out the effect of modification, role of type of clay and type of modifiers on the characteristics of organo clays by comparing the physico chemical characteristics of different modified and unmodified clays. The organic modification of montmorillonitc clays with long chain organic cation is found to increase their lattice spacing with the amount of modification whereas no such increase was observed on modification of kaolinitic clays even when all the exchangeable inorganic cations were replaced with the organic cations. The XRD studies revealed that the intercalated organic cations of the modified montmorillonite clays assumed mono, bi, or pseudo tri layer depending on the extent of organic modification. Irrespective of the type of clay modified or the modifier used all the organo clays tend to become e hydrophobic, and the surface area of the clays was found to decrease. A comparison of the characteristics of clays modified in laboratory with organo clay obtained commercially revealed that the organic modification was more effective for the organo clay prepared in the laboratory. As the index properties of all clays are generally correlated with their geotechnical characteristics, the effect of organic modification on the index properties of clays was studied. Chapter 3 presents the effect of organic modification on the plasticity and free swell behavior of clays. The index properties of commercially available organo clay and the unmodified clay used for its preparation were evaluated with pore fluids of different dielectric constants. Fluids of varied dielectric constants were chosen as it is one of the important characteristics to understand the behavior of clays. It was observed that the organic modification of clays reduced the plasticity of the clays in water and increased the plasticity in less polar liquids like ethanol. As the organo clays are more hydrophobic, the water holding capacity and plasticity in water is decreased to a large extent. The free swell behavior of clays in different pore fluids were assessed in terms of the modified free swell index. It was found that trend of variation of free swell index with dielectric constant for modified and unmodified clays, as in the case of plasticity is quite opposite. The swell volume of the modified clays was observed to be controlled more by surface solvation than by the development of the inter particle repulsive forces and diffused double layer. The effect of incorporating unmodified bentonite with organically modified clay on the index properties of bentonite has also been studied. The results suggested that the effect of organo clay addition to bentonite was always to reduce its plasticity and free swell in water. However in pore fluids of lower dielectric an increase in the plasticity and free swell was observed with increasing organo clay content in the mixture. This owes to the fact that organo clays can interact strongly with organic fluids, changing its fabric arrangement. As reported from literature it is well established that the swell of clays has conflicting role on the stability and permeability of clay barriers. Swelling of clays is liable to cause a reduction in hydraulic conductivity, enhance the retention times of contaminants and attribute self healing capacity to the liners. Even though extensive studies have been carried out on the swell behaviour and mechanism of swell of unmodified clays, no systematic research is reported on the effect of organic modification on swell behavior of clays especially in the presence of different pore fluids. Chapter 4 describes the results of oedometer swell tests carried out on compacted samples of modified, unmodified clays and organo clay –bentonite mixture in the presence of different pore fluids such as water, ethanol, and their mixture and carbon tetra chloride. Swelling ability of the unmodified clays was not completely suppressed even in the presence of low polar miscible organic liquids as they were molded at water contents corresponding to the optimum moisture content (OMC). The order of the swelling for the unmodified bentonites was in the order of the polarity of the pore fluids used, while the order is reversed upon organic modification of clays. The mechanism of swell in the case of organo clays in organic liquids was related to the solvation of the organic liquid by the intercalated organic cations. And unlike in the case of unmodified clays, the organo clays showed “solvent induced swelling”. Both organic modification and addition of organo clay to bentonite resulted in the suppression of the swelling of clays in water irrespective of the type of modifier or the extent of organic modification. The Chapter 5 gives a detailed account of the compressibility behavior of organically modified clays and its mixtures with bentonite when the samples were molded with water at their respective OMC and later inundated with different fluids. Significant differences were observed on the compressibility of modified and unmodified clay in different fluids. Organic modification of clays reduced their affinity to water and resulted in lowering the compressibility. However there was an increased compressibility for the organo clays when the samples were inundated with non polar liquids and the compression of the organo clay in non polar fluid was not influenced by the nature of clay nor by the type of modifier. The compressibility of the mixtures of organo clay and bentonite in non polar liquids was generally controlled by the organo clay component of the mixture. Organo clays can be recommended as additives in bentonite slurries for construction of slurry walls in order to improve the containment of organics. But the amendment should not compromise the stability and integrity of the slurry walls. Moreover the influence of addition of sorptive material like organo clay on the compressibility behavior of bentonite slurry has received little attention and needs serious consideration as the studies in the previous chapter has brought out that the compressibility of compacted bentonite reduced significantly on organic modification as well as on addition of orgno clay. The Chapter 6 deals with the compressibility behavior of slurries of unmodified bentonite, organo clay, and their mixtures molded with respective liquid limits with water and later inundated with fluids of different dielectric constants as the slurries frequently get in contact with fluids other than water during their operational life. However it was observed that the effect of polarity of the inundating liquid is masked in all the cases by the presence of large amount of initial molding water as the possible specific chemical interactions between organo clay and non polar fluids were restricted in the presence of large amount of molding water. But the slurry samples molded and inundated with non polar carbon tetra chloride showed that the organo clay samples are more compressible when molded with carbon tetrachloride. The chapter also gives a brief discussion on the effect of initial molding water content on the compressibility of organo clays and its mixtures. The compression was found to increase with increase in initial water content irrespective of the type of inundating fluid in agreement with the behavior observed in the case of unmodified clays. However the effect was less pronounced at higher applied pressures. The Chapter 7 brings out the volume change behavior of organo clay amended sand bentonite mixtures (SOB) which form potential barrier to prevent and /or remove contaminants. The compaction behavior of mixtures showed that the degree of compaction achieved was controlled mainly by the sand content and proportion of organo clay in the total fine fraction. The volume change behavior of the SOB mixtures were assessed with the help of oedometer tests conducted on mixtures compacted at OMC conditions and inundated with different fluids same as those used for the swell tests. The samples with higher sand content showed no observable swell when inundated with liquids viz., water, ethanol and their mixture as all the swollen finer particles were accommodated in the voids created by sand particles. However a high swell percentage was measured when samples with high organo clay content were inundated with carbon tetrachloride. Moreover with increased amounts of organo clay in the mix the swelling of bentonite was suppressed and the same trend continued even when the pore fluids were changed to liquids of medium polarity. The organo clays are capable of interacting strongly with non polar liquids like carbon tetra chloride, and hence an appreciable swell was noted when inundated with them especially in the case of mixtures with high organo clay content. The swell behavior of SOB mixtures with lower sand contents were controlled mostly by the interaction of the pore fluid with bentonite and organo clay, interactions between organo clay and bentonite and the polarity of the pore fluid. As the pore fluid polarity was decreased the influence of organo clay component of the mixture was more pronounced. The Chapter 8 explains the hydraulic performance of modified and unmodified clays along with that of the mixtures of organo clay with bentonite and SOB. The coefficient of permeability was calculated from the consolidation data obtained on sample molded at OMC. The permeability variations observed on changing the pore fluids were studied at each applied pressure. The hydraulic conductivity showed a decreasing trend with the increase in applied pressure for all the clays. The specific interactions of the organo clay with the pore fluids and the clay content were found to play a role in controlling the permeability. Limited tests were carried out to simulate a condition where a SOB liner is proposed as a secondary liner below a punctured geo membrane and its hydraulic performance was evaluated with diesel and water as pore fluids. The permeability coefficients with diesel as permeant were observed to decrease with increase in organo clay content of the mixture irrespective of the applied pressure where as the reverse was true when permeated with water. Thus the use of SOB as secondary liner below storage tanks so as to control the transport of contaminants leaking containments systems is established. The organic sorption efficiency of the modified and unmodified clays and the mixture were evaluated in terms of removal of total organic carbon (TOC) and reduction in chemical oxygen demand (COD) of the different leachates including municipal solid waste (MSW) leachate when treated with different types of modified and unmodified clays. All the modified clays irrespective of the type of clay or the type of modifier used showed improved organic sorption capacity. The sorption of TOC was found to follow a linear sorption mechanism in the case of organo clays and the organic contaminants were partitioned on to the organic phase attached to the organo clays. The composition, age and type of leacahte played a major role in controlling the organic sorption efficiency of organo clays in the case of MSW leachates. The studies done with different mixtures of organo clay and bentonite and SOB mixtures clearly proved that the addition of organo clay always enhanced the organic sorption efficiency of the mixtures. The results are discussed in Chapter 9. The Chapter 10 highlights the major conclusions drawn from the study. The study, apart from satisfying the research zeal on understanding the behavior of organo clays, has generated important information useful for the geo environmental engineer to arrive at appropriate design of barrier systems incorporating organically modified clay, based on the characteristics of pore fluid.

Soft soil deposits of coastal regions and lowland areas pose many geotechnical problems but it is indispensable to utilize these grounds to meet the growing demand for infrastructure with ever increasing urbanization and industrial development. Soft soils are generally associated with high compressibility and low strength characteristics which augment the risk of huge settlements and foundation failure. It is essential to understand the complex behaviour of the ground consisting of soft clays as construction and maintenance of infrastructure in these areas is challenging. Marine sediments mostly possess open microstructure irrespective of the differences in their mineral composition and sedimentation environment. Also this particular microstructure in marine sediments is generally accompanied by the presence of a great amount of organic residues and fragments of marine organisms. Formation of pyrite is also possible because of the presence of decomposable organic matter, dissolved sulfate and reactive iron minerals. These soils due to their inherent mineralogy and microstructure have high void ratios and consequently high water holding capacity which explains the reason for their low shear strength and high compressibility characteristics. And often the formation environment is conducive for incorporation of organic content in the soft clay deposits which further aggravates the problem. A complete characterization of the soil can enhance the understanding of soil behavior and therefore can play a crucial role in suggesting suitable and sustainable ground improvement method. Soft clay deposits of Kuttanad area in Kerala, India extending to varying depths below the ground level, present a challenge as a foundation soil due to low bearing capacity and high settlement. Geologically Kuttanad is considered as a recent sedimentary formation. In the geological past, the entire area was a part of the Arabian Sea. Presently Kuttanad area covers an area of about 1,100 km2. Many intriguing reports of distresses to structures founded on this soil are available. An over view of specific characteristics of soft clays along with the comprehensive description of soft clays from various parts of the world is presented in the introductory Chapter. Deep soil mixing and mass stabilization methods are found to be relatively advantageous in reducing differential settlements and in achieving expeditious construction. A more detailed review of literature on Kuttanad soil problems and various ground improvement methods adopted are presented. The different ground improvement techniques attempted are soil reinforcement, stone columns, preloading etc. Soil mixing can be relatively advantageous over the other conventional ground improvement methods. Laboratory studies carried out earlier with different binders such as cement, lime and lime fly ash combinations did not exhibit appreciable improvement in soil strength. It is reasoned that the lack of understanding of the soil characteristics is responsible for the limited success of these attempts. Based on the review of literature the detailed scope of the work is presented at the end of Chapter 1. The method of collection of the soil from Kuttanad region, methods adopted for characterization of soil, characteristics of various binders used and testing procedures adopted for assessing the geotechnical behavior with and without binders are described in Chapter 2. In order to characterize the soil for understanding its behaviour under different conditions as well as to gauge its response to different stabilizers, a detailed physico¬chemical, mineralogical, morphological and fabric studies are carried out and presented in Chapter 3. An attempt has been made to explain the role of components of soils such as organic substances, pyrite and sesquioxides for variations in its properties with change in water content. The high water holding capacity of the soil reflected in its Liquid limit along with relatively low plasticity characteristics of the soil has been explained as due to the presence of minerals such as metahalloysite and gibbsite, the flocculated fabric, porous organic matter and water filled diatom frustules (amorphous silica). Based on the study conducted on the plasticity characteristics of Kuttanad soil under different conditions of drying and treatment, it was brought about that the organic content plays a dominant role in particle cementation and aggregation causing a substantial reduction in plasticity upon drying. Further, the presence of minerals such as pyrite and iron oxides also account for the plasticity changes. The significant changes in soil properties upon drying have also been successfully explained in Chapter 4. Attempts made to stabilize the soil using conventional chemical stabilizers are described in Chapter 5. The effect of binders on the strength improvement of soil has been explained based on the changes occurring in the composition, fabric and physico-chemical characteristics of soil upon addition of the binders. Lack of strength development in soil with lime has been attributed to the inherent composition of the soil hindering the formation of pozzolanic compounds and unfavourable modification of the fabric. On the other hand the soil responded well to cement stabilisation. The influence of various parameters such as Water/Cement (W/C) ratio, Initial water content, curing period and additive dosage on the strength development of cement treated soil has been examined. Cement improved the strength of the soil by binding the soil particles without depending on the interaction with the soil. It was observed that the role of initial water content is insignificant and the strength improved with reducing W/C ratio. The dependence of strength development with cement addition on the fabric at different W/C ratios has been assessed. Also the role of other additives such as Lime, Sand, Fly Ash, Ground granulated blast furnace slag, Silica fume and Sodium silicate to enhance the strength of cement treated soil has been analysed in Chapter 5. It was shown that only Sodium Silicate (NS) along with cement meets with good success. The studies on the undrained shear strength and compressibility characteristics of cemented soil carried out to understand the strength and deformation behaviour of the cemented soil are presented in Chapter 6. It is clear from the compressibility characteristics of the cemented soil that there is a well defined yield stress demarcating the least compressible pre-yield zone and more compressible post yield zone. Generally the yield stress increases with reducing water cement ratio. It is interesting to note that the post yield compressibility of the cemented soil is controlled more by the fabric of soil than by cementation effect. The study on the undrained shear behavior of cemented soil revealed that the cohesion intercept and angle of internal friction increases with addition of cement. However the impact of cementation is reflected more as increase in cohesion intercept with increasing cement content. The uniqueness of failure envelope observed for the cemented soil irrespective of whether the confining stress is above or below the yield stress has been explained in detail. A case study on the performance of embankment founded on Kuttand soil improved with Deep mixed cement columns (DMCC) has been evaluated through numerical simulations using FLAC 2D and this forms the subject matter of Chapter 7. For this work the soil properties of the Kuttanad soil determined by experimental investigations have been used. The simulation results showed that the introduction of DMCC columns improved the factor of safety against failure and reduced settlements. This study clearly endorses the analysis and the results of the test carried out on Kuttanad soil. The final chapter summarizes the details of the work carried out which brings out the importance of characterization of the soil in terms of soil components, physico-chemical environment as well as the micro structure of the soil in predicting the behaviour of the soil in changing environment and to understand the stabilization response of the soil with different binders which intern helps to select appropriate binder and or binder combinations.

Ideal magnetohydrodynamics (MHD) simulations are known to have problems in satisfying the solenoidal constraint (i.e. the divergence of magnetic field should be equal to zero, $<p>ablacdotvec{B} = 0$). The simulations become unstable unless specific measures have been taken.<p><p>In this thesis, a solenoidal constraint satisfying technique that allows discrete satisfaction of the solenoidal constraint up to the machine accuracy is presented and validated with a variety of test cases. Due to its inspiration from Chorin's artificial compressibility method developed for incompressible CFD applications, the technique was named as \ / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

<div>Large protein molecules are abundant in biological cells but are very difficult to study in physiological conditions due to molecular disorder. For large proteins, most structural information is obtained in crystalline states which can be achieved in certain conditions at very low temperature. X-ray and neutron crystallography methods can then be used for determination of crystalline structures at atomic level. However, in solution at room or physiological temperatures such highly resolved descriptions cannot be obtained except in very few cases. Scattering methods that can be used to study this type of structures at room temperature include small-angle x-ray and neutron scattering. These methods are used here to study two distinct proteins that are both classified as glycoproteins, which are a large class of proteins with diverse biological functions. In this study, two specific plasma glycoproteins were used: Fibrinogen (340 kDa) and Alpha 1-Antitrypsin or A1AT (52 kDa). These proteins have been chosen based on the fact that they have a propensity to form very large molecular aggregates due to their tendency to polymerize. One goal of this project is to show that for such complex structures, a combination of scattering methods that include SAXS, SANS, and DLS can address important structural and interaction questions despite the fact that atomic resolution cannot be obtained as in crystallography. A1AT protein has been shown to have protective roles of lung cells against emphysema, while fibrinogen is a major factor in the blood clotting process. A systematic approach to study these proteins interactions with lipid membranes and other proteins, using contrast-matching small-angle neutron scattering (SANS), small angle x-ray scattering (SAXS) and dynamic light scattering (DLS), is presented here. A series of structural reference points for each protein in solution were determined by performing measurements under osmotic stress controlled by the addition of polyethylene glycol-1,500 MW (PEG 1500) in the samples. Osmotic pressure changes the free energy of the molecular mixture and has consequences on the structure and the interaction of molecular aggregates. In particular, the measured radius of gyration (Rg) for A1AT shows a sharp structural transition when the concentration of PEG 1500 is between 33 wt\% and 36 wt\%. Similarly, a significant structural change was observed for fibrinogen when the concentration of PEG 1500 was above 40 wt\%. This analysis is applied to a study of A1AT interacting with lipid membranes and to a study of fibrinogen polymerization in the presence of the enzyme thrombin, which catalyzes the formation of blood clots. The experimental approach presented here and the applications to specific questions show that an appropriate combination of scattering methods can produce useful information on the behavior and the interactions of large protein systems in physiological conditions despite the lower resolution compared to crystallography.</div>