Analysis of the static and dynamic behaviour of hydraulic fills

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(1)E.T.S. DE INGENIEROS DE CAMINOS, CANALES Y PUERTOS GROUND ENGINEERING AND MORPHOLOGY DEPARTMENT / DEPARTAMENTO DE INGENIERÍA Y MORFOLOGÍA DEL TERRENO. ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS. PhD THESIS. MANUEL DÁVILA MADRID Ingeniero de Caminos, Canales y Puertos MADRID, 2014. PhD THESIS: ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS.. UNIVERSIDAD POLITÉCNICA DE MADRID.

(2) UNIVERSIDAD POLITÉCNICA DE MADRID. DEPARTAMENTO DE INGENIERÍA Y MORFOLOGÍA DEL TERRENO. ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS.. TESIS DOCTORAL MANUEL DÁVILA MADRID Ingeniero de Caminos, Canales y Puertos Directores de Tesis: CLAUDIO OLALLA MARAÑÓN Dr. Ingeniero de Caminos, Canales y Puertos ENRIQUE ASANZA IZQUIERDO Dr. Ingeniero de Caminos, Canales y Puertos MADRID, 2014. PhD THESIS: ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS.. E.T.S. DE INGENIEROS DE CAMINOS, CANALES Y PUERTOS.

(3) TÍTULO DE TESIS / THESIS TITLE:. Autor / Author:. D. Manuel Dávila Madrid. Directores / Directors:. D. Claudio Olalla Marañón D. Enrique Asanza Izquierdo. Tribunal nombrado por el Mgfco. Y Excmo. Sr. Rector de la Universidad Politécnica de Madrid, el día …... de …………………………. de 2014. Presidente D. …………………………………………………………………………….. Vocal 1º D. ……………………………………………………………………………... Vocal 2º D.…………………………………………………………………………………... Vocal 3º D. ………………………………………………………………………………... Secretario D. ………………………………………………………………………………. Realizado el acto de defensa y lectura de la tesis el día ……. de ………………… de 2014 en ……………………………., los miembros del tribunal acuerdan otorgar la calificación de : ……………………………………………………………………………. .. EL PRESIDENTE. LOS VOCALES. EL SECRETARIO. PhD THESIS: ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS.. ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS / ANALISIS DEL COMPORTAMIENTO ESTÁTICO Y DINÁMICO DE RELLENOS HIDRÁULICOS.

(4) En la actualidad existe un gran conocimiento en la caracterización de rellenos hidráulicos, tanto en su caracterización estática, como dinámica. Sin embargo, son escasos en la literatura estudios más generales y globales de estos materiales, muy relacionados con sus usos y principales problemáticas en obras portuarias y mineras. Los procedimientos semi‐empíricos para la evaluación del efecto silo en las celdas de cajones portuarios, así como para el potencial de licuefacción de estos suelos durantes cargas instantáneas y terremotos, se basan en estudios donde la influencia de los parámetros que los rigen no se conocen en gran medida, dando lugar a resultados con considerable dispersión. Este es el caso, por ejemplo, de los daños notificados por el grupo de investigación del Puerto de Barcelona, la rotura de los cajones portuarios en el Puerto de Barcelona en 2007. Por estos motivos y otros, se ha decidido desarrollar un análisis para la evaluación de estos problemas mediante la propuesta de una metodología teórico‐numérica y empírica. El enfoque teórico‐numérico desarrollado en el presente estudio se centra en la determinación del marco teórico y las herramientas numéricas capaces de solventar los retos que presentan estos problemas. La complejidad del problema procede de varios aspectos fundamentales: el comportamiento no lineal de los suelos poco confinados o flojos en procesos de consolidación por preso propio; su alto potencial de licuefacción; la caracterización hidromecánica de los contactos entre estructuras y suelo (camino preferencial para el flujo de agua y consolidación lateral); el punto de partida de los problemas con un estado de tensiones efectivas prácticamente nulo. En cuanto al enfoque experimental, se ha propuesto una metodología de laboratorio muy sencilla para la caracterización hidromecánica del suelo y las interfaces, sin la necesidad de usar complejos aparatos de laboratorio o procedimientos excesivamente complicados. Este trabajo incluye por tanto un breve repaso a los aspectos relacionados con la ejecución de los rellenos hidráulicos, sus usos principales y los fenómenos relacionados, con el fin de establecer un punto de partida para el presente estudio. Este repaso abarca desde la evolución de las ecuaciones de consolidación tradicionales (Terzaghi, 1943), (Gibson, English & Hussey, 1967) y las metodologías de cálculo (Townsend & McVay, 1990) (Fredlund, Donaldson and Gitirana, 2009) hasta las contribuciones en relación al efecto silo (Ranssen, 1985) (Ravenet, 1977) y sobre el fenómeno de la licuefacción (Casagrande, 1936) (Castro, 1969) (Been & Jefferies, 1985) (Pastor & Zienkiewicz, 1986). Con motivo de este estudio se ha desarrollado exclusivamente un código basado en el método de los elementos finitos (MEF) empleando el programa MATLAB. Para ello, se ha esablecido un marco teórico (Biot, 1941) (Zienkiewicz & Shiomi, 1984) (Segura & Caron, 2004) y numérico (Zienkiewicz & Taylor, 1989) (Huerta & Rodríguez, 1992) (Segura & Carol, 2008) para resolver problemas de consolidación multidimensional con condiciones de contorno friccionales, y los correspondientes modelos constitutivos (Pastor & Zienkiewicz, 1986) (Fiu & Liu, 2011). Asimismo, se ha desarrollado una metodología experimental a través de una serie de ensayos de laboratorio para la calibración de los modelos constitutivos y de la caracterización de parámetros índice y de flujo (Castro, 1969) (Bahda 1997) (Been & Jefferies, 2006). Para ello se han empleado arenas de Hostun como material (relleno hidráulico) de referencia. Como principal aportación se incluyen una serie de nuevos ensayos de corte directo para la caracterización hidromecánica de la interfaz suelo – estructura de hormigón, para diferentes tipos de encofrados y rugosidades.. PhD THESIS: ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS.. RESUMEN.

(5) La constante actualización de los parámetros del suelo, hace también de este algoritmo una potente herramienta que permite establecer un interesante juego de perfiles de variables, tales como la densidad, el índice de huecos, la fracción de sólidos, el exceso de presiones, y tensiones y deformaciones. En definitiva, el modelo otorga un mejor entendimiento del efecto silo, término comúnmente usado para definir el fenómeno transitorio del gradiente de presiones laterales en las estructuras de contención en forma de silo. Finalmente se incluyen una serie de comparativas entre los resultados del modelo y de diferentes estudios de la literatura técnica, tanto para el fenómeno de las consolidaciones por preso propio (Fredlund, Donaldson & Gitirana, 2009) como para el estudio del efecto silo (Puertos del Estado, 2006, EuroCódigo (2006), Japan Tech, Stands. (2009), etc.). Para concluir, se propone el diseño de un prototipo de columna de decantación con paredes friccionales, como principal propuesta de futura línea de investigación.. PhD THESIS: ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS.. Finalmente, se han diseñado una serie de algoritmos específicos para la resolución del set de ecuaciones diferenciales de gobierno que definen este problema. Estos algoritmos son de gran importancia en este problema para tratar el procesamiento transitorio de la consolidación de los rellenos hidráulicos, y de otros efectos relacionados con su implementación en celdas de cajones, como el efecto silo y la licuefacciones autoinducida. Para ello, se ha establecido un modelo 2D axisimétrico, con formulación acoplada u‐p para elementos continuos y elementos interfaz (de espesor cero), que tratan de simular las condiciones de estos rellenos hidráulicos cuando se colocan en las celdas portuarias. Este caso de estudio hace referencia clara a materiales granulares en estado inicial muy suelto y con escasas tensiones efectivas, es decir, con prácticamente todas las sobrepresiones ocasionadas por el proceso de autoconsolidación (por peso propio). Por todo ello se requiere de algoritmos numéricos específicos, así como de modelos constitutivos particulares, para los elementos del continuo y para los elementos interfaz. En el caso de la simulación de diferentes procedimientos de puesta en obra de los rellenos se ha requerido la modificacion de los algoritmos empleados para poder así representar numéricamente la puesta en obra de estos materiales, además de poder realizar una comparativa de los resultados para los distintos procedimientos..

(6) Wide research is nowadays available on the characterization of hydraulic fills in terms of either static or dynamic behavior. However, reported comprehensive analyses of these soils when meant for port or mining works are scarce. Moreover, the semi‐empirical procedures for assessing the silo effect on cells in floating caissons, and the liquefaction potential of these soils during sudden loads or earthquakes are based on studies where the underlying influence parameters are not well known, yielding results with significant scatter. This is the case, for instance, of hazards reported by the Barcelona Liquefaction working group, with the failure of harbor walls in 2007. By virtue of this, a complex approach has been undertaken to evaluate the problem by a proposal of numerical and laboratory methodology. Within a theoretical and numerical scope, the study is focused on the numerical tools capable to face the different challenges of this problem. The complexity is manifold; the highly non‐linear behavior of consolidating soft soils; their potentially liquefactable nature, the significance of the hydromechanics of the soil‐structure contact, the discontinuities as preferential paths for water flow, setting “negligible” effective stresses as initial conditions. Within an experimental scope, a straightforward laboratory methodology is introduced for the hydromechanical characterization of the soil and the interface without the need of complex laboratory devices or cumbersome procedures. Therefore, this study includes a brief overview of the hydraulic filling execution, main uses (land reclamation, filled cells, tailing dams, etc.) and the underlying phenomena (self‐weight consolidation, silo effect, liquefaction, etc.). It comprises from the evolution of the traditional consolidation equations (Terzaghi, 1943), (Gibson, English, & Hussey, 1967) and solving methodologies (Townsend & McVay, 1990) (Fredlund, Donaldson and Gitirana, 2009) to the contributions in terms of silo effect (Ranssen, 1895) (Ravenet, 1977) and liquefaction phenomena (Casagrande, 1936) (Castro, 1969) (Been & Jefferies, 1985) (Pastor & Zienkiewicz, 1986). The novelty of the study lies on the development of a Finite Element Method (FEM) code, exclusively formulated for this problem. Subsequently, a theoretical (Biot, 1941) (Zienkiewicz and Shiomi, 1984) (Segura and Carol, 2004) and numerical approach (Zienkiewicz and Taylor, 1989) (Huerta, A. & Rodriguez, A., 1992) (Segura, J.M. & Carol, I., 2008) is introduced for multidimensional consolidation problems with frictional contacts and the corresponding constitutive models (Pastor & Zienkiewicz, 1986) (Fu & Liu, 2011). An experimental methodology is presented for the laboratory test and material characterization (Castro 1969) (Bahda 1997) (Been & Jefferies 2006) using Hostun sands as reference hydraulic fill. A series of singular interaction shear tests for the interface calibration is included. Finally, a specific model algorithm for the solution of the set of differential equations governing the problem is presented. The process of consolidation and settlements involves a comprehensive simulation of the transient process of decantation and the build‐up of the silo effect in cells and certain phenomena related to self‐compaction and liquefaction. For this, an implementation of a 2D axi‐syimmetric coupled model with continuum and interface elements, aimed at simulating conditions and self‐weight consolidation of hydraulic fills once placed into floating caisson cells or close to retaining structures. This basically concerns a loose granular soil with a negligible initial effective stress level at the onset of the process. The implementation requires a specific numerical algorithm as well as specific constitutive models for both the continuum and the interface elements. The simulation of implementation procedures for the fills has required the modification of the. PhD THESIS: ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS.. ABSTRACT.

(7) Furthermore, the continuous updating of the model provides an insightful logging of variable profiles such as density, void ratio and solid fraction profiles, total and excess pore pressure, stresses and strains. This will lead to a better understanding of complex phenomena such as the transient gradient in lateral pressures due to silo effect in saturated soils. Interesting model and literature comparisons for the self‐weight consolidation (Fredlund, Donaldson, & Gitirana, 2009) and the silo effect results (Puertos del Estado (2006), EuroCode (2006), Japan Tech, Stands. (2009)). This study closes with the design of a decantation column prototype with frictional walls as the main future line of research.. PhD THESIS: ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS.. algorithm so that a numerical representation of these procedures is carried out. A comparison of the results for the different procedures is interesting for the global analysis..

(8) I would like to take this opportunity to thank the people who contributed to this research and without whom this would not have gone ahead and had success. I would like to particularly thank my Thesis directors and supervisors, Dr Professor Claudio Olalla and Dr Enrique Asanza. Their practical knowledge and attention to detail taught me many valuable lessons and furthered my understanding of geotechnical engineering greatly. Their assistance and continue motivation in editing and analyzing the research performed was essential for the success of my doctoral programme. Special thanks also go to Dr Professor Manuel Pastor and Dr Pablo Mira and the rest of the members of the Computational Geomechanics Group in CEDEX, Ana Sofía Benítez and Silvia Sancho, who share their time of research with me. I am very thankful for their practical support in completing the aspects of this research related to the numerical computation and software programming. I greatly enjoyed my time with them at the office in CEDEX, where their assistance greatly improved my understanding in this field, as well as the enjoyment of our free time in the laboratory. I would also like to thank the members of “Applied Geotechnics” Department in CEDEX that I was part: Dr Roberto Fernández, Dr Áurea Perucho, José Antonio Díez and specially Dr José Manuel Martínez Santamaría, for their constant assistance in analysing and improving of the research performed and for the search of financial aid. I have benefited greatly from their insights and assistance. Special thanks go also to Institute of Geotechnical Engineering and Construction Management of the Hamburg University of Technology (TUHH), particularly in the figure of Prof. Dr. Ing. Jürgen Grabe for the global support given, to carry out a short stay in Hamburg. The Geotechnical Laboratory of the National Public Works and Engineering Research Centre (CEDEX), throughout the figure of its Director Dr Fernando Pardo, also deserves acknowledgement for the financial support provided for this project through a four year scholarship – research staff training contract. I also would like to highlight the special aid received by the laboratory staff, especially José María Toledo, Clemente Arias and J. Luis Miranda, and the Responsible of the Triaxials Laboratory, Dr. Jose Estaire, who put their trust on me to carry out the test laboratory campaign necessary to achieve the empirical goals of this research. Also special thanks to Dr Marta Sánchez, from Central Structures Laboratory in CEDEX, for the collaboration in the preparation of concrete specimen for the laboratory tests. My enduring gratitude goes to all my family; specially my parents, Manolo and María, and my sister Isabel who supported and encouraged me throughout my education. Finally, I would like to thank all my closer friends, whose encouragement and support enabled me to pursue my interest in this research.. PhD THESIS: ANALYSIS OF THE STATIC AND DYNAMIC BEHAVIOUR OF HYDRAULIC FILLS.. ACKNOWLEDGEMENTS.

(9) INDEX RESUMEN ..................................................................................................................... 4 ABSTRACT..................................................................................................................... 6 ACKNOWLEDGEMENTS ................................................................................................ 8 1. INTRODUCTION AND TARGETS ............................................................................. 1 1.1. INTRODUCTION. ........................................................................................... 1. 1.2. MAIN TARGETS............................................................................................. 1. 2. HYDRAULIC FILLS. STATE OF KNOWLEDGE. .......................................................... 5 2.1 2.1.1 2.1.2 2.2 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.3 2.3.1 2.3.2 2.3.3 2.3.4 2.4 2.4.1 2.4.2. A GENERAL HYDRAULIC FILLS SCOPE. .......................................................... 5 Hydraulic fills main uses. Construction methods reclamation. ............. 5 Fill mass properties and general classifications..................................... 8 SELF WEIGHT LARGE STRAIN CONSOLIDATION. ........................................ 15 Literature overview. Significant additions. .......................................... 15 Coordinate Systems. ............................................................................ 19 Theory review. The Dependent Variable. ............................................ 20 Constitutive Equations. ........................................................................ 25 Conclusions. ......................................................................................... 25 ARCH‐SILO EFFECT. FLOATING CAISSON CELLS. ........................................ 26 Introduction ......................................................................................... 26 Construction aspects. .......................................................................... 28 Actions affection of caisson cells. ........................................................ 31 Actions estimations.............................................................................. 33 LIQUEFACTION OF HYDRAULIC FILLS. ........................................................ 35 Historical review of liquefaction phenomena. .................................... 35 Theory review. ..................................................................................... 41. 3. NUMERICAL MODELING. ..................................................................................... 51 3.1. INTRODUCTION .......................................................................................... 51. Manual Pequeñas Presas para Países en Desarrollo. I|P a g e.

(10) 3.2 3.2.1 3.2.2 3.3 3.3.1 3.3.2 3.3.3 3.4 3.4.1 3.4.2 3.5 3.5.1 3.5.2 3.6 3.6.1 3.6.2. HYDRO‐MECHANICAL DESCRIPTION. ......................................................... 51 Continuous elements ........................................................................... 51 Interface elements ............................................................................... 59 FEM IMPLEMENTATION. ............................................................................ 61 Continuous elements ........................................................................... 61 Interface elements and discontinuous porous media. ........................ 69 FEM implementation particularities. ................................................... 77 CONSTITUTIVE MODELS. CLASSIC AND GENERALIZED PLASTICITY. .......... 82 Continuous elements. .......................................................................... 82 Interface elements. ............................................................................ 108 ALGORITHM ADAPTION TO THE HIGHLY NON‐LINEAR PROBLEM. ......... 114 Continuous elements ......................................................................... 114 Interface elements ............................................................................. 123 FEM IMPLEMENTATION OF THE DYNAMIC PROBLEM. ........................... 130 Continuous elements ......................................................................... 130 Interface elements ............................................................................. 135. 4. LABORATORY CHARACTERISATION CAMPAIGN................................................ 140 4.1. INTRODUCTION ........................................................................................ 140. 4.2. HOSTUN SANDS AS MATERIAL EMPLOYEED. ........................................... 140. 4.3. FILLS LABORATORY CHARACTERISTATION............................................... 141. 4.3.1 Triaxial Tests. ..................................................................................... 141 4.3.2 Triaxial Test Results. Strength, deformational and flux characterisation. ............................................................................................... 155 4.3.3 Isotropic consolidation in the triaxial cell. Deformational and flux characterisation. ............................................................................................... 158 4.3.4 Oedometers Test results. Deformational and Flux characterisation. 163 4.4 4.4.1 4.4.2 4.4.3. CONSTITUTIVE MODEL ASIGNATION FOR THE INTERFACE. .................... 168 Direct Shear Test. ............................................................................... 168 Shear Test results. Strength and deformational characterisation. ... 174 Shear Test results. Flow characterisation. ......................................... 179. 5. CALIBRATION OF THE FEM MODEL AND CALCULATIONS. ................................ 183 5.1. FEM MODEL VERIFICATIONS.................................................................... 183. Manual Pequeñas Presas para Países en Desarrollo. II | P a g e.

(11) 5.2. GENERAL CONSOLIDATION AND SETTLEMENTS...................................... 183. 5.3. LIMIT LOAD PROBLEM BY DISPLACEMENT CONTROL ............................. 185. 5.4. INTERFACE CONSOLIDATION ................................................................... 197. 5.5. DYNAMIC ELASTIC PROBLEM ................................................................... 199. 5.6. SELF‐WEIGHT CONSOLIDATION PROBLEM .............................................. 207. 5.7. SILO EFFECT CHECKING ............................................................................ 213. 5.7.1 5.7.2 5.7.3 5.7.4. Introduction to the problem .............................................................. 213 Silo effect analysis for wooden formwork concrete walls................. 219 Silo effect analysis for metal formwork concrete walls..................... 221 Analysis of Silo effect results ............................................................. 224. 5.8. IMPLEMENTATION PROCEDURE AND EXTERNAL LOAD APPLICATION. .. 226. 5.9. JACOBIAN MATRIX MODIFICATION ......................................................... 231. 5.10. NUMERICAL VERIFICATIONS OF THE MODEL .......................................... 235. 6. DESIGN AND SETUP OF A FULLY INSTRUMENTED COLUMN OF FILLS DECANTATION.......................................................................................................... 237 6.1 6.1.1 6.1.2 6.2 6.2.1 6.2.2 6.3 6.3.1 6.3.2 6.3.3 6.4 6.4.1. BACKGROUND. ......................................................................................... 237 Introduction. ...................................................................................... 237 Research experiences. ....................................................................... 238 THEORETICAL LAYOUT. ............................................................................ 240 General description. .......................................................................... 240 Operating scheme. ............................................................................. 243 TECHNICAL DETAILS LAYOUT. .................................................................. 245 Mechanical layout .............................................................................. 245 Instrumentation and monitoring ....................................................... 250 Data acquisition system ..................................................................... 251 COLUMN SETUP. ...................................................................................... 252 Equipment setup steps: ..................................................................... 252. 7. CONCLUSIONS AND FUTURE RESEARCH LINES. ................................................ 256 7.1. CONCLUSIONS. ......................................................................................... 256. Manual Pequeñas Presas para Países en Desarrollo. III | P a g e.

(12) 7.1.1 7.1.2 7.1.3 7.2 7.2.1 7.2.2. Theoretical and numerical approach. ................................................ 256 Laboratory approach. ........................................................................ 257 Algorithm implementation and results. ............................................ 258 FUTURE RESEARCH LINES. ....................................................................... 261 Decantation column........................................................................... 261 Future theoretical and laboratory research lines. ............................. 261. APPENDIXES ............................................................................................................. 273 APPENDIX A .............................................................................................................. 274 APPENDIX B .............................................................................................................. 287. Manual Pequeñas Presas para Países en Desarrollo. IV | P a g e.

(13) FIGURE INDEX Figure 1. Trailing Suction Hopper Dredger, TSHD (Hydraulic Fill Manual, 2012). ................................... 6 Figure 2. Rainbowing (Hydraulic Fill Manual, 2012). .............................................................................. 7 Figure 3. Staged bund construction under water using a grab dredger (Hydraulic Fill Manual, 2012). . 8 Figure 4. Fines / Water Content / Solid Content diagram (Scott & Cymerman, 1984). ........................ 11 Figure 5. Formation of clay balls on the reclamation area (Hydraulic Fill Manual, 2012). ................... 12 Figure 6. Pre‐loading of subsoil and effect of vertical drains (Hydraulic Fill Manual, 2012). ............... 13 Figure 7. Crane mounted with tandem vibratory probes (Hydraulic Fill Manual, 2012). ..................... 14 Figure 8. Dynamic compaction machine (Hydraulic Fill Manual, 2012)................................................ 14 Figure 9. Behavior scheme proposed by Imai (1981). .......................................................................... 17 Figure 10. Comparison of Eulerian and Lagrangian coordinate systems (Schiffman, Vick, & Gibson, 1988). .......................................................................................................................................... 19 Figure 11. Different relationships of describing soil deformations. ..................................................... 22 Figure 12. Comparative of lateral pressures. ........................................................................................ 27 Figure 13. 3D perspective of a floating caisson. ................................................................................... 28 Figure 14. Floating dock construction process sequences.................................................................... 29 Figure 15. Continuum sliding process. .................................................................................................. 29 Figure 16. Caisson installation procedures. .......................................................................................... 30 Figure 17. Filling of the caisson cells with rainbowing techniques. ...................................................... 31 Figure 18. Final layout / section of a floating dock. .............................................................................. 31 Figure 19. Pressures exerted when filling a cell (Silo Effect). ............................................................... 32 Figure 20. Dock : Loads exerted on the outer wall at the service stage (Silo Effect). ........................... 32 Figure 21. Compression stresses exerted upon the inner wall (Silo Effect).......................................... 33 Figure 22. Pressures distribution when filling a cell (Silo Effect) according to Spanish code. .............. 34 Figure 23. Aerial view of Fort Peck failure (U.S. Army Corps of Engineers, 1939)). .............................. 36 Figure 24. Nerlerk B‐67 berm and foundation cross section (from Been et al., 1987, with permission NRC of Canada). .......................................................................................................................... 37 Figure 25. Apartment building at Kawagishi‐cho in 1964 Niigata earthquake (Kawasumi‐Hirosi, 1968). ..................................................................................................................................................... 37 Figure 26. Liquefaction failure of Lower San Fernando Dam after the 1971 earthquake (University of California, Berkeley). ................................................................................................................... 38 Figure 27. Aerial view of the Merriespruit tailings dam failure showing the path of the mudflow (Fourie et al., 2001). .................................................................................................................... 39 Figure 28. Gulf Canada’s Molikpaq structure in the Beaufort Sea........................................................ 40. Manual Pequeñas Presas para Países en Desarrollo. V|P a g e.

(14) Figure 29. Details of cyclic ice loading and excess pore pressure (Jefferies & Been, 2006). ................ 40 Figure 30. Failure of embankment on Ackermann Lake triggered by vibroseis trucks (from Hryciw et al., 1990)...................................................................................................................................... 41 Figure 31. Triaxial tests on dense and loose sands (Zienkiewicz et al., 1999). ..................................... 42 Figure 32. Difference between rate and absolute definitions of dilatancy (Jefferies & Been, 2006). .. 42 Figure 33. Critical void ratio hypothesis from direct shear tests (Casagrande, 1975). ......................... 43 Figure 34. Definición del Parámetro de estado (después de Been & Jefferies, 1985). ......................... 44 Figure 35. Instability or flow liquefaction line for onset of liquefaction (after Yang, 2002). ................ 45 Figure 36. Collapse surface representation for onset of liquefaction (after Yang, 2002)..................... 46 Figure 37. Liquefaction types according to Robertson & Fear (1996). ................................................. 47 Figure 38. Scheme for soil undrained behaviour for triaxial compression under static load. (Robertson y Wride, 1998). ............................................................................................................................ 47 Figure 39. Scheme for soil cyclic undrained behaviour illustrating cyclic liquefaction in a sample with initial shear stress. (adapatada de Robertson y Wride, 1998). ................................................... 49 Figure 40. Scheme of the aperture and u variable for the interface. ................................................... 60 Figure 41. Elements implemented in the hydraulic fills model. ........................................................... 63 Figure 42. Eight‐node quadratic and four‐node linear quadrilateral elements. ................................... 64 Figure 43. Zero‐thickness interface elements for the contact. ............................................................. 70 Figure 44. Scheme of the axi‐symmetry of the model. ......................................................................... 80 Figure 45. Capped DP model. Yield surface (De Souza et al., 2008). .................................................... 84 Figure 46. Capped DP model. Flow vectors (De Souza et al., 2008). .................................................... 85 Figure 47. Drucker‐Prager model. Return mapping to cone and apex. ................................................ 90 Figure 48. Modified Cam‐Clay model. Yield surface. ............................................................................ 91 Figure 49. CDP model. Algorithm for selection of the correct return‐mapping procedure (De Souza et al., 2008)...................................................................................................................................... 97 Figure 50. Theoretical yield surface for Pastor Zienkiewicz model..................................................... 104 Figure 51. Schematic behaviour of undrained sand for different Dr (in % per one)........................... 105 Figure 52. Coulomb yield locus for an interface element. .................................................................. 110 Figure 53. Shear behaviour predicted by the Fu‐Liu model. ............................................................... 114 Figure 54. Empirical Relationships for Estimating Hydraulic Conductivity. ........................................ 118 Figure 55. Hostun sands size grain curve. ........................................................................................... 141 Figure 56. Triaxial Cell with Tubular Load cell Mounted Directly in the Loading Piston (Garlanger, 1970). ........................................................................................................................................ 142 Figure 57. Illustration of sample preparation methods for clean sands (from Ishihara 1993). .......... 144 Figure 58. Sample preparation process. ............................................................................................. 146. Manual Pequeñas Presas para Países en Desarrollo. VI | P a g e.

(15) Figure 59. CO2 flushing process for the fully saturation..................................................................... 147 Figure 60. Skempton’s B values verification process. ......................................................................... 148 Figure 61. CO2 Isotropic consolidation and volumetric strain monitoring process............................ 149 Figure 62. Deviatoric stress application with piston displacement in triaxial cell. ............................. 150 Figure 63. Volume changes during triaxial test (for a drained test on a dilatant sample).................. 150 Figure 64. Potential error in void ratio during saturation (from Sladen and Handford, 1987)........... 151 Figure 65. Saturation influence on the void ratio (Bahloul, 1990)...................................................... 152 Figure 66. Isotropic compressibility curves (El Hachem, 1987). ......................................................... 152 Figure 67. Membrane penetration scheme. ....................................................................................... 153 Figure 68. Normalized membrane penetration vs grain size (Salden et al., 1985). ............................ 154 Figure 69. Comparison of CSL determined from load controlled and strain rate controlled triaxial compression tests (Been & Jefferies, 2006). ............................................................................. 154 Figure 70. Lubricated end platen for triaxial testing of sands. ........................................................... 155 Figure 71. Drained behavior of Hostun Sand in compression triaxial test; the variation of deviatoric stress with axial strain, for Dr = 60 %. ....................................................................................... 157 Figure 72. Hostun sand stress paths for PZ model calibration for different ranges of Dr. Loose (a) and Medium Dense (b) (some tests from Bahda F. PhD Thesis, 1997). ........................................... 158 Figure 73. Isotropic consolidation process for a sample ICC‐1. .......................................................... 159 Figure 74. Isotropic consolidation graph for Hostun Sand. ................................................................ 160 Figure 75. Determination of t90 through the consolidation curve. Taylor Method. .......................... 162 Figure 76. Graph with the permeability – void ratio relationship for Hostun Sand. .......................... 163 Figure 77. Oedometer graph for Hostun Sands tests. ........................................................................ 164 Figure 78. Taylor method application to time curves. ........................................................................ 166 Figure 79. Medium loose Hostun sand permeability evolution with void ratio. ................................ 168 Figure 80. Stress conditions in the simple shear test. ........................................................................ 169 Figure 81. Formwork specimen preparation (wooden and metallic formwork). ............................... 172 Figure 82. Specimen preparation for Direct Shear Test...................................................................... 173 Figure 83. Hostun sand – concrete structure (wooden formwork) test results calibration with Fu‐Liu model. ....................................................................................................................................... 176 Figure 84. Hostun sand – concrete structure (metal formwork) test results calibration with Fu‐Liu model. ....................................................................................................................................... 177 Figure 85. Soil‐concrete interfaces strength. ...................................................................................... 178 Figure 86. Soil‐concrete interfaces normal strain behaviour (b). ....................................................... 178 Figure 87. Deformational results for initial consolidation in shear tests. ........................................... 180 Figure 88. Taylor method application to time curves. ........................................................................ 181. Manual Pequeñas Presas para Países en Desarrollo. VII | P a g e.

(16) Figure 89. Graph with the permeability – void ratio relationship for Hostun Sands. ......................... 182 Figure 90. Scheme of the settlement – consolidation problem. ........................................................ 184 Figure 91. Analytical and FEM results comparison. ............................................................................ 185 Figure 92. Non linear coupled FE code structure based on the Newton‐Raphson method. .............. 185 Figure 93. Limit load for a FEM problem. ........................................................................................... 186 Figure 94. Geometry of the limit load analysis for a circular footing. ................................................ 192 Figure 95. Approximated failure shape due to a bearing pressure. ................................................... 193 Figure 96. Limit load by the FEM model problem for the Von Mises case. ........................................ 194 Figure 97. Failure shape due to a bearing pressure with the FEM model for the Von Mises case..... 194 Figure 98. Load‐displacements curves by the Drucker‐Prager perfectly plastic models with different material constants (Chen, W.F. & Liu, X.L. “Limit Analysis in Soil Mechanics”, 1990). ............. 195 Figure 99. Limit load by the FEM model for the CDP model for the compression (a) and extension (b) case............................................................................................................................................ 195 Figure 100. Failure shape due to a bearing pressure with the FEM model for the CPD in extension.196 Figure 101. Initial failure wedge (represented by plastic strains) due to bearing pressure with the FEM model for the CPD in extension. ....................................................................................... 196 Figure 102. Discontinuity consolidation problem geometry. ............................................................. 197 Figure 103. Fluid pressure distributions at different times from FEM model and analytically. ......... 199 Figure 104. Discontinuity settlements evolution with time from FEM model.................................... 199 Figure 105. Scheme for one‐dimensional dynamic stress equilibrium. .............................................. 200 Figure 106. Scheme for one‐dimensional wave transmission. ........................................................... 202 Figure 107. Geometry of the dynamic problem for a P wave input at the base. ............................... 203 Figure 108. Geometry of the dynamic problem for an S wave input at the base............................... 203 Figure 109. P and S waves with time for the dynamic problem. ........................................................ 204 Figure 110. P and S waves with space for the dynamic problem. ...................................................... 205 Figure 111. Graphic results with P wave displacement versus time from dynamic FEM model. ....... 206 Figure 112. Graphic results with S wave displacement versus time from dynamic FEM model. ....... 206 Figure 113. Schematic soil/discontinuity index parameters. .............................................................. 208 Figure 114. Schematic FEM algorithm structure for self‐weight large strain consolidation problems. ................................................................................................................................................... 209 Figure 115. FEM model and FSConsol polynomial relationship for compressibility. .......................... 210 Figure 116. FEM model and FSConsol polynomial relationship for permeability ............................... 211 Figure 117. FSConsol analysis input parameters in compressibility and permeability. ...................... 211 Figure 118. FEM model and FSConsol results for void ratio versus height with time. ....................... 212 Figure 119. FEM model and FSConsol results for pore pressure dissipation along the vertical. ........ 212. Manual Pequeñas Presas para Países en Desarrollo. VIII | P a g e.

(17) Figure 120. FEM model and FSConsol results for settlement evolution with time along the vertical. ................................................................................................................................................... 212 Figure 121. FEM model results for pore pressure dissipation process at all nodes. .......................... 213 Figure 122. FEM model results for the final solid fraction and relative density disposition. ............. 213 Figure 123. Example of a caisson with lightening circular cells. ......................................................... 216 Figure 124. Axi‐symmetric geometry of the caisson cell for the FEM model. .................................... 217 Figure 125. Mesh of caisson cell axisymmetry model and boundary conditions. .............................. 218 Figure 126. Initial vertical and horizontal thrust (a) and tensional state rotation through Lode’s Angle (b) induced by the contact (in red) at 10% consol. ................................................................... 219 Figure 127. FEM model results for wooden formwork interface.(a) vertical displacements and (b) Relative Density at 95% consol. ................................................................................................ 219 Figure 128. Densification at Gauss points affected (red) or not (blue) by the interface interaction; (a) void ratio evolution and (b) stress paths until 95% consol. ...................................................... 220 Figure 129. FEM model results for PZ stress path (a); and dependency between void ration and effective stress (b) and permeability (c) for wooden formwork. .............................................. 221 Figure 130. FEM model results for evolution of pore pressure dissipation (a) and settlement (b) evolution with time for wooden formwork. ............................................................................. 221 Figure 131. FEM model results for metal formwork interface.(a) vertical displacements and (b) Relative Density at 95% consol.; (c) pore pressure excess at 70% consol................................. 222 Figure 132. FEM model results for PZ stress path (a); and dependency between void ration and effective stress (b) and permeability (c) for metal formwork. .................................................. 223 Figure 133. FEM model results for evolution of pore pressure dissipation (a) and settlement (b) evolution with time for metal formwork. ................................................................................. 223 Figure 134. Horizontal Thrust with silo effect for wooden and metal formwork according SPA recommendations and FEM model for the 95% of consolidation............................................. 225 Figure 135. Vertical stresses with silo effect for wooden and metal formwork according SPA recommendations and FEM model for the 95% of consolidation............................................. 225 Figure 136. Silo effect evolution when permeability of continuum and interfaces are considerably different (a) or similar (b). ......................................................................................................... 226 Figure 137. Schematic activation of the gravity at the FEM algorithm structure, simulating a) Siphoning and b) Pouring. ......................................................................................................... 227 Figure 138. Comparisons FEM results between Pouring and Siphoning procedures a) Lateral Thrust b) Tensile vertical stresses. ............................................................................................................ 228 Figure 139. Comparisons FEM results between Pouring / Siphoning procedures for Void Ratio evolution with time at different heights. .................................................................................. 229. Manual Pequeñas Presas para Países en Desarrollo. IX | P a g e.

(18) Figure 140. Comparisons FEM results between Pouring / Siphoning procedures for Void Ratio evolution with time at initial stages of consolidation. .............................................................. 229 Figure 141. Comparisons between general lateral thrust laws at geotechnical engineering with silo effect results.............................................................................................................................. 230 Figure 142. Comparisons between general lateral thrust laws at geotechnical engineering with silo effect results.............................................................................................................................. 230 Figure 143. Comparisons between general lateral thrust laws at geotechnical engineering with silo effect results.............................................................................................................................. 231 Figure 144. Iterations for convergence with time/step in silo effect analysis with modified and non‐ modified Jacobian matrix. ......................................................................................................... 233 Figure 145. Residue after attaining convergence with time/step in silo effect analysis with modified and non‐modified Jacobian matrix............................................................................................ 234 Figure 146. Comparisons between general lateral thrust laws at geotechnical engineering with silo effect results.............................................................................................................................. 235 Figure 147. Comparisons between general lateral thrust laws at geotechnical engineering with silo effect results.............................................................................................................................. 236 Figure 148. Examples of sedimentation tests devices: (a) Pedroni et al. (2008); (b) Miller et al. (2010) and (c) Tan et al. (1992) ............................................................................................................ 240 Figure 149. Scheme of pressure and friction forces. .......................................................................... 242 Figure 150. Operating scheme. Working steps. .................................................................................. 244 Figure 151. Fitting details of the tongue and groove joint. ................................................................ 246 Figure 152. Details of the modules of the column.............................................................................. 246 Figure 153. Details of the supporting bench coupled to the overflow tank. ...................................... 247 Figure 154. Details of the horizontal support structure of the column. ............................................. 248 Figure 155. Details of the instrumented central rod. ......................................................................... 249 Figure 156. Pumping equipment (by pulses) for siphoning. ............................................................... 249 Figure 157. Slurry agitation tank and pumping equipment. ............................................................... 250 Figure 158. Piezoresistive sensor. ....................................................................................................... 251 Figure 159. Levelling of the bedplate. ................................................................................................ 253 Figure 160. Connection of the siphoning system to the column. ....................................................... 253 Figure 161. Assembly of the column modules and supporting structure. .......................................... 254 Figure 162. Assembly of the instrumented central rod. ..................................................................... 255. Manual Pequeñas Presas para Países en Desarrollo. X|P a g e.

(19) TABLE INDEX Table 1. Relative density Re as function of placement method (Hydraulic Fill Manual, 2012). ............. 9 Table 2. Constitutive relationships employed in consolidation models (Hawlader et al (2008)). ........ 18 Table 3. Gaussian integration points positions and weight factors. ..................................................... 79 Table 4. Classification of sands for different DR. ................................................................................. 105 Table 5. Empirical Relationships for Estimating Hydraulic Conductivity. ........................................... 117 Table 6. Main index parameters of Hostun RF Sands. ........................................................................ 141 Table 7. Triaxial test samples. Test properties at failure. ................................................................... 156 Table 8: Medium loose Hostun sand; the parameters of Pastor‐Zienkiewicz model ......................... 157 Table 9. Isotropic Consolidation samples results................................................................................ 160 Table 10. Isotropic consolidation test. Volume change vs. Square Root of time. .............................. 161 Table 11. Consolidation parameters and permeability values from the isotropic consolidation test. ................................................................................................................................................... 162 Table 12. Oedometer samples results. ............................................................................................... 164 Table 13. Oedometer consolidation test. Vertical Strain vs. Square Root of time. ............................ 165 Table 14. Consolidation parameters and permeability values from the oedometer test. ................. 167 Table 15. Cements resistant to sea water. ......................................................................................... 171 Table 16. Specimen concrete batching. .............................................................................................. 172 Table 17. Sand ‐ concrete samples; initial conditions. ........................................................................ 174 Table 18. Sand ‐ concrete contact; the parameters of Fu‐Liu model. ................................................ 175 Table 19. Normal and shear failure stress pairs for sand ‐ concrete contact. .................................... 178 Table 20. Initial consolidations results in shear tests for soil – concrete contact. ............................. 179 Table 21. Oedometer consolidation test. Vertical Strain vs. Square Root of time. ............................ 180 Table 22. Flow parameters from the initial consolidation at shear tests. .......................................... 182 Table 23. Geometrical parameters of the problem. ........................................................................... 184 Table 24. Soil properties and settlement expected. ........................................................................... 184 Table 25. Soil properties and bearing capacity expected for Von Mises case. ................................... 193 Table 26. Soil properties and bearing capacity expected for the Capped Drucker Prager case. ........ 195 Table 27. Discontinuity hydromechanic properties and analytical results. ........................................ 198 Table 28. Initial wave properties. ....................................................................................................... 203 Table 29. Soil 1 and 2 properties and expected wave parameters. .................................................... 204 Table 30. Soil 1 and 2 impedance and wave amplitude estimations. ................................................. 205 Table 31. Hostun sand; the parameters of Pastor‐Zienkiewicz model for the self‐weight consolidation problem. .................................................................................................................................... 210. Manual Pequeñas Presas para Países en Desarrollo. XI | P a g e.

(20) Table 32. Hostun sand; the parameters of Pastor‐Zienkiewicz model for the silo effect problem. ... 217 Table 33. Hostun sand – concrete structure (wooden formwork); the parameters of Fu‐Liu model for the silo effect problem. ............................................................................................................. 217 Table 34. Hostun sand – concrete structure (metal formwork); the parameters of Fu‐Liu model for the silo effect problem. ............................................................................................................. 217. Manual Pequeñas Presas para Países en Desarrollo. XII | P a g e.

(21) UPM ‐ ETSICCP. Analysis of static and dynamic behaviour of hydraulic fills.. 1. INTRODUCTION AND TARGETS 1.1. INTRODUCTION.. Hydraulic fills are generally used in civil works, especially for land reclamation projects. The aim with these materials is the creation of new land by raising the elevation of any low‐lying land (either seabed or riverbed) or by pumping out the water from a watery area which is enclosed by dikes. However, this technique, and hence these materials, are also implemented for the construction of tailing dams for the storage of mining waste and also for the filling of the floating caisson cells taking part of the quay walls. Hydraulic filling is defined as the creation of new land by the following general procedures: 1.. Dredging of fill material in a borrow/dredging area by floating equipments called dredgers. In case of mining waste treatment, the fill material comes from the mine operation facilities.. 2.. Transport of fill material from the dredging area to the reclamation site by transport elements such as dredges, barges or pipes.. 3.. Placement of fill material as a mixture of fill material and water in the reclamation area or in the tailing dams. Due to the fully (or almost fully) saturated state of the fill, it becomes a key feature for this study.. As a result of the importance of these materials in civil and geotechnical engineering, hydraulic fills embrace the main doctoral thesis topic. Although there exists a wide research on the characterization of the hydraulic fills in terms of either static or dynamic behaviour, it tends to be more difficult to find reported comprehensive analysis into these soils. Therefore, this study is addressed to conform a better understanding of these filling materials assuming the real ways of implementation. This approach also takes into consideration the soil nature as saturated, loose and generally granular materials.. 1.2. MAIN TARGETS.. This analysis incorporates several points and sections, attending to aims required for the analysis of these materials. The main aim is thus the consecution of a useful tool to deepen in the knowledge of the hydromechanical behaviour of the hydraulic fills, particularly to reproduce the behaviour when implemented as slurry deposition within retaining (cylindrical) structures and during the decantation and consolidation processes. In consecuense, a global approach is necessary, and thus these analysis sections are going from the development of a general overview about the main uses of fills (reclamation lands, filled cells, tailing dams, etc.), up to the main associated phenomenon and problematics linked to hydraulic fills (self‐ weight large consolidation, silo effect, liquefaction, etc.). The study also incorporates a theoretical, numerical and empirical analysis, and finalizes with the design of a decantation column prototype provided with frictional walls and dynamic equipment, and the monitoring of the main behaviour parameters.. Analysis of the static and dynamic behaviour of hydraulic fills. 1|P a g e.

(22) UPM ‐ ETSICCP. Analysis of static and dynamic behaviour of hydraulic fills.. Therefore, several researching lines are open within this study, underlying the targets linked to this analysis. ‐. A theoretical and numerical approach is required for the consecution of a powerful numerical tool. Accordingly, the Biot’s equations are subjects of study for a future formulation of the self‐weight consolidation phenomena concerning the laying of these soils. In this framework, a coupled code based on the Biot theory and on the Finite Element Method (FEM) through techniques of spatial and time discretization, is chosen for the analysis. Specific body and hydraulic charges should also be considered, since they affect most of the hydraulic fills implementations.. ‐. A set of appropriate constitutive models should be taken into consideration for this granular material, in accordance to the associated phenomenon. An overview of these related phenomena is strongly useful for a better choice of the constitutive model representing these granular soils. For instance, the framework of Generalized Plasticity is interesting for the constitutive modeling selection, as well as the possibility of the reproduction of associated behavior such as volumetric plasticity, hardening and liquefaction.. ‐. The behavior of hydraulic fills, when supported on concrete walls or dikes as for the floating caisson cells, possesses a relevant impact in civil works. This aspect requires the implementation of specific elements capable to reflect this soil–concrete interaction, as an especial boundary condition. By virtue of this, Biot’s specific formulation for (zero‐thickness) interface elements [Segura & Carol, 2008] and its implementation in a FEM code is also objective of this study, to reproduce the hydromechanical behavior of the contact. This is essential to understand the transitory phenomena of the silo effect concerning this structure because of the introduction of a conducting channel for water throughout the interface and consequently for pore pressure dissipation. This would have great influence in the whole process since the presence of a discontinuity is expected to accelerate the consolidation process. Furthermore, the rate of consolidation also depends on the aperture of the discontinuity, tightly related to the flow pressure and the coupled mechanical response.. ‐. The mechanical behaviour of the interfaces is also object of study. A model describing the overlapped zone of the contact, dependent on the effective normal stress, is thus necessary for interfaces.. ‐. The development of an axisymmetric model, simulating conditions of the floating caisson cell interior, would provide wide results of the behaviour of these soils when implemented in these concrete cylinders. However, the placement procedures of the fill are supposed to be an important variable for the final results. Therefore, several new algorithms should be analysed for the numerical representation of the procedures, with the aim of comparing the results. External loads should also be implemented to the model at the end of the consolidation in order to visualize its influence on the main parameters and differences from fill deposition procedures.. ‐. The global structure of the algorithm should incorporate two numerical approaches. First of all, the model should start with a negligible effective stress state, which will also depend on the implementation procedure selected. Furthermore, this starting point should match with the initial index parameter state of the soil. Therefore, the model needs to include the updating of the soil / fluid mass force vectors by a gradual increase of the gravity, which will allow the model to start with the proposed initial state. Secondly, a complementary algorithm focusing on the variable updating should be performed at the end of every. Analysis of the static and dynamic behaviour of hydraulic fills. 2|P a g e.

(23) UPM ‐ ETSICCP. Analysis of static and dynamic behaviour of hydraulic fills.. incremental loop, as the force vector is also assumed to change with those new density values. ‐. The results of the model, mainly the silo effect results, are also verified through benchmarking with the reported data obtained experimentally or analytically. However, most of analytical and empirical expressions come from the industrial engineering of storage silos; hence, some differences may be drawn with this specific model. Special attention should be paid to the special boundary conditions in cells, in relation to the storage silos, such as the restricted vertical movements at the bottom, and also to the soil– concrete interfaces as preferential path for pore pressure dissipation. This may involve some differences in the results with regards to those coming from the storage silo, for dried and flowing materials.. ‐. A more advanced algorithm for the resolution of the system of equations is also pursued. The non‐linear nature of the problem and the material behaviour involves slower resolution processes, where convergence of the numerical solution becomes slower or is even never obtained. Therefore, a full and more advanced methodology of resolution is expected to reduce the global computational cost.. ‐. A series of laboratory tests should be carried out to better understand the behaviour of these soft materials and their contact with concrete surface. Therefore, the laboratory test campaign is focused on the calibration of the constitutive models and also to provide the geomaterial and the interfaces with deformational and flow parameters.. ‐. The performance of common laboratory tests (triaxial test, direct shear tests, oedometer tests) is also inside the scope of this document. Both triaxial and shear tests are used worldwide to determine the shear strength and stress strain behaviour of soils. Triaxial tests are thus used to evaluate the constitutive behaviour of these soft soils through consolidated undrained tests (CU), where the excess of pore pressure is measured to determine the effective characteristics. Direct shear tests are also inside this approach, not uniquely to determine the hydromechanical characteristics of the soil, but also the hydromechanical properties of the soil – concrete contacts. The development of a new methodology for the performance of direct shear box tests with interfaces would require a specific procedure to prepare interface specimens. These specimens would be made up of soft soil and concrete tablets with different typology of formwork to illustrate the variability of the construction procedures in the field. A new proposal for the definition of the flow and deformational parameters of the interface should be accomplished to solve the coupled hydromechanical characterization. The concept of an equivalent width is strongly necessary for this point and should be developed within this analysis. Moreover, this is of particular importance due to the lack of rigourous knowledge of permeability at mixed interfaces.. ‐. A full verification of the numerical model should be carried out through an advanced physical scale model in the shape of a decantation column. This test would represent the implementation of hydraulic fills in civil structures (floating caisson cells). Therefore, a decantation column prototype should be proposed and designed, consisting of a fully instrumented column simulating conditions of hydraulic fills. This would be aimed at obtaining a comprehensive characterization of the soil (i.e., density profiles, total and excess pore pressure, strength and stress‐strain characterization, etc), which will be basically used to calibrate the FEM model and to be compared with it. This will also provide with a better understanding of all phenomena concerning this fills, such as the gradient in lateral pressures (the silo effect) and the dynamic response of the soil for future analyses.. Analysis of the static and dynamic behaviour of hydraulic fills. 3|P a g e.

(24) UPM ‐ ETSICCP. ‐. Analysis of static and dynamic behaviour of hydraulic fills.. New researching lines are also encouraged to be open to widen this area of knowledge, mainly in topics related to dynamic characterisation of highly non linear parameters and the calibration of the axisymmetric model throughout a decantation column test.. Analysis of the static and dynamic behaviour of hydraulic fills. 4|P a g e.

(25) UPM ‐ ETSICCP. Analysis of static and dynamic behaviour of hydraulic fills.. 2. HYDRAULIC FILLS. STATE OF KNOWLEDGE. 2.1. A GENERAL HYDRAULIC FILLS SCOPE.. 2.1.1. Hydraulic fills main uses. Construction methods reclamation.. The use of hydraulic fills in civil engineering is not a recent invention; for instance, archaeological evidence indicates that land reclamation has existed for thousands of years. In some of the tidal and swampy areas of north of Netherlands and Germany, artificial dwelling mounds were built to protect themselves against flooding some 2000 years ago. Later, around 1500 A.D. a new method was established. “Polders” were constructed by building a ring dike in shallow areas, after which the water was removed from the enclosed low‐lying area by windmill‐driven pumps and, once steam engines became available in the 19th century, by pumping stations. Nevertheless, the most significant moment came through when the modern centrifugal pumps were developed and enabled the current large‐scale reclamations projects by hydraulic filling. On the other hand, tailing dam constructions, linked to mining projects, have been developed over the last century and recent years. Most of them have also been carried out adopting pumping stations and flexible pipelines. However, the main use of hydraulic fills is for land reclamation, either for extended areas or either for the floating caisson cell filling. A brief overview of the hydraulic filling execution (from dredging, treatment of borrow areas, and transportation) is undertaken in order to better understand the whole process, the subjected phenomena and the associated behaviour of these materials. Prior to start with an overview of the filling operations, a general plan for reclamation works should be considered for the dredging, transportation and the reclamation activities. Accordingly, the construction of a hydraulic fill infrastructure involves a number of consecutive phases: ‐. Dredging/mining of the fill material;. ‐. Transport of this material to the reclamation site;. ‐. Placement of the fill at the designated location;. ‐. If necessary, improvement of the subsoil and/or the fill material;. Finally, the design of soil structures, such as embankments for land reclamations and tailing dams, should be capable to predict the safety of these structures against collapse or excessive deformation, under the various loading conditions which are deemed possible.. 2.1.1.1 Dredging techniques Prior to deepen in dredging techniques, it is worth to point out some definitions related to hydraulic fills. A borrow area is a designated area known either to contain sufficient fill material of adequate quality, or to be dredged as a part of another project, without much consideration to the suitability of the material. The quantitative assessment of the potential borrow area should also be considered when undertaking reclamation projects. Also the differences of the density of the fill material in‐situ, and the material after being placed and compacted within the reclamation area (bulking) should be taken into consideration. Furthermore, several combinations of equipments or dredge chains can be thought of for the dredging, transportation and placing of the dredged material. For instance, for a suction dredging, the material is pumped by a dredger through a discharge pipeline into the reclamation area; besides,. Analysis of the static and dynamic behaviour of hydraulic fills. 5|P a g e.

(26) UPM ‐ ETSICCP. Analysis of static and dynamic behaviour of hydraulic fills.. for a mechanical dredging, material is placed in a barge alongside the dredger, in the hopper of the dredger itself or even directly on land. A review of most typical types of dredging equipment and methodologies are included to provide the reader with some basic knowledge. Some of the main dredging equipments regarding suction dredging are: ‐. Plain Suction Dredger. This equipment is based on the erosive action of the water flow which enters the mouth of the suction pipe of the dredger as a result of the vessel’s pumping action. The eroded material is a sand‐water mixture which is finally pumped through the discharge pipeline towards the reclamation site.. ‐. Cutter Suction Dredger. The principle of this equipment is based on a combination of mechanical and suction dredging. The material to be dredged is cut with the dredger’s cutter head and loosened with the erosive action of the water which flows towards the suction mouth by the vessel’s pumping action. The sand‐water mixture is transported through the discharge pipeline into the reclamation area.. ‐. Trailing Suction Hopper Dredger (TSHD). This equipment also uses a combination of mechanical dredging (by cutting) and suction power to loosen the material. However, it is self‐propelled, and the material is pumped into the vessel’s hopper until it is completely filled and the dredge material is finally discharged in the reclamation site (Figure 1).. Figure 1. Trailing Suction Hopper Dredger, TSHD (Hydraulic Fill Manual, 2012). ‐. Backhow dredger. This is basically a hydraulic excavator installed on a pontoon, which uses spuds to secure its position when dredging. The spuds elevate the pontoon in the dredging position, so that considerable excavation forces are delivered to the seabed.. ‐. Grab dredger. This equipment consists of a wire crane installed on a pontoon, and may be anchored by wires or with spuds. Since the dredger uses a wire suspended grab, the maximum dredging force is determined by the weight and design of the grab only. One advantage is that the dredging depth is not limited, but it cannot attain underneath structures.. ‐. Bucket dredger. This is provided with a chain of buckets mounted on a ladder. This ladder is lowered to the seabed and material is cut by the individual buckets while the chain rotates around the top and lower end of the ladder.. 2.1.1.2 Transport of fill material Transport of fill material from the borrow area to the reclamation site can be carried out either by hydraulic transport through pipelines or by hopper dredgers or barges. Depending on the pump capacity of the dredger and boosters, the pumping distance for fine sands and silt may reach up to 15 km and more. Boosters pump stations can be used to increase the pumping capacity. Hydraulic transport through floating pipelines is the most common method for reclamation operations. Part of the floating pipeline may be a sinker line; as a result, it reduces hindrance to. Analysis of the static and dynamic behaviour of hydraulic fills. 6|P a g e.

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