Introduction to the Physics of Cohesive Sediment Dynamics in the Marine Environment

by Winterwerp; van Kesteren

• ISBN13: 9780444515537
• ISBN10: 0444515534
• eBook ISBN(s): 9780444515537
• Additional ISBN(s): 9780444515537, 9780444515537
• Format: Hardcover
• Copyright: 2004-06-01
• Publisher: Elsevier Science

Summary

This book is an introduction to the physical processes of cohesive sediment in the marine environment. It focuses on highly dynamic systems, such as estuaries and coastal seas. Processes on the continental shelf are also discussed and attention is given to the effects of chemistry, biology and gas. The process descriptions are based on hydrodynamic and soil mechanic principles, which integrate at the soil-water interface. This approach is substantiated through a classification scheme of sediment occurrences in which distinction is made between cohesive and granular material. Emphasis is also placed on the important interactions between turbulent flow and cohesive sediment suspensions, and on the impact of flow-induced forces on the stability of the seabed. An overview of literature on cohesive sediment dynamics is presented and a number of new developments are highlighted, in particular in relation to floc formation, settling and sedimentation, consolidation, bed failure and liquefaction and erosion of the bed. Moreover, it presents a summary on methods and techniques to measure the various sediment properties necessary to quantify the various parameters in the physical-mathematical model descriptions. A number of examples and case studies have been included.

Table of Contents

1. Introduction	1	(4)
2. Boundary layer flow	5	(24)
2.1 Hydrodynamics and mass balance	5	(9)
2.1.1 The mean water movement	5	(3)
2.1.2 The mass balance for suspended sediment	8	(2)
2.1.3 The kappa-Eturbulence model	10	(4)
2.2 The boundary layer	14	(10)
2.2.1 The structure of the boundary layer	14	(6)
2.2.2 Coherent structures in the boundary layer	20	(4)
2.3 The effect of surface waves	24	(5)
3. The nature of cohesive sediment	29	(58)
3.1 The composition of cohesive sediment	30	(14)
3.1.1 Granular composition of cohesive sediment	30	(5)
3.1.2 Mineral composition of cohesive sediment	35	(6)
3.1.3 Organic composition of cohesive sediment	41	(3)
3.2 Skeleton fabric composition of cohesive sediment	44	(8)
3.2.1 Inter-particle forces	44	(6)
3.2.2 Pore size distribution	50	(2)
3.3 Geotechnical classification of cohesive sediment	52	(20)
3.3.1 Geotechnical parameters	52	(6)
3.3.2 Application to in-situ conditions	58	(14)
3.4 Cohesive sediment in the marine environment	72	(15)
3.4.1 Phenomenological classification of cohesive sediment	72	(6)
3.4.2 Mud content of sand-mud mixtures	78	(4)
3.4.3 Fluid mud	82	(5)
4. Flocculation processes	87	(34)
4.1 Introduction	88	(5)
4.2 Fractal structure of mud flocs	93	(3)
4.3 Flocculation model	96	(15)
4.3.1 Number equation for flocs	96	(3)
4.3.2 Aggregation processes	99	(1)
4.3.3 Floc break-up processes	100	(3)
4.3.4 Eulerian flocculation model	103	(3)
4.3.5 Lagrangean flocculation model	106	(3)
4.3.6 Comparison with field data	109	(2)
4.4 Flocculation time	111	(10)
4.4.1 The gelling concentration	111	(2)
4.4.2 Non-equilibrium conditions	113	(8)
5. Settling and sedimentation	121	(40)
5.1 Introduction	122	(2)
5.2 Settling velocity and floc size	124	(14)
5.2.1 Settling velocity and floc size in still water	124	(3)
5.2.2 Hindered settling	127	(11)
5.3 Deposition and sedimentation	138	(23)
5.3.1 Deposition rate	138	(13)
5.3.2 Sedimentation in flowing water	151	(4)
5.3.3 Sedimentation in harbour basins	155	(6)
6. Sediment-fluid interaction	161	(50)
6.1 Introduction	163	(2)
6.2 Sediment-fluid interaction -literature overview	165	(15)
6.2.1 Non-cohesive sediment	165	(6)
6.2.2 Low-concentration mud suspensions	171	(4)
6.2.3 High-concentration mud suspensions	175	(5)
6.3 Sediment-induced buoyancy effects	180	(27)
6.3.1 The concept of saturation	180	(13)
6.3.2 HCMs in a turbidity maximum	193	(7)
6.3.3 HCMS and rapid siltation	200	(7)
6.4 Sediment-fluid interaction in the benthic boundary layer	207	(4)
7. Self-weight consolidation	211	(42)
7.1 Introduction - classical theory	211	(3)
7.2 The Gibson consolidation equation	214	(4)
7.3 Special cases of the Gibson equation	218	(3)
7.3.1 Terzaghi's consolidation theory	218	(1)
7.3.2 Kynch's sedimentation theory	219	(2)
7.4 Material functions for the Gibson equation	221	(4)
7.5 Application of Gibson's equation	225	(3)
7.6 Fractal description of bed structure	228	(5)
7.6.1 Effective stress	228	(3)
7.6.2 Permeability	231	(2)
7.7 Consolidation as an advection-diffusion process using fractal theory	233	(6)
7.8 Material functions for fractal approach	239	(4)
7.9 Application of fractal approach	243	(3)
7.10 Approximated solution of consolidation equation	246	(7)
8. Mechanical behaviour	253	(90)
8.1 The seafloor as a multi-phase system	254	(10)
8.1.1 Effective stress concept	255	(2)
8.1.2 Drained and undrained behaviour	257	(4)
8.1.3 Compressibility of gaseous water	261	(3)
8.2 Stress-strain relations	264	(20)
8.2.1 Elastic and plastic strains	264	(3)
8.2.2 Elastic stress-strain relations	267	(3)
8.2.3 Elasto-plastic stress-strain relations	270	(3)
8.2.4 Cohesive sediment constitutive relations	273	(11)
8.3 Failure mechanisms	284	(26)
8.3.1 Type of failure	284	(5)
8.3.2 Tensile failure	289	(9)
8.3.3 Tensile failure parameters	298	(5)
8.3.4 Shear failure	303	(7)
8.4 Cyclical behaviour	310	(15)
8.4.1 Cyclic stress-strain relations	311	(8)
8.4.2 Examples of cyclical loading	319	(6)
8.5 Strain-rate dependent behaviour	325	(18)
8.5.1 Range of strain rates	325	(2)
8.5.2 Rheological behaviour	327	(5)
8.5.3 Creep	332	(4)
8.5.4 Dynamic response	336	(7)
9. Erosion and entrainment	343	(40)
9.1 Phenomenological description of erosion	343	(2)
9.2 Literature on erosion	345	(12)
9.2.1 Erosion formulae	345	(4)
9.2.2 Effect of physico-chemical parameters	349	(8)
9.3 Classification scheme for erosion	357	(5)
9.4 Entrainment of fluid mud layers	362	(8)
9.5 Erosion as a drained/undrained process	370	(15)
9.5.1 Flow-induced erosion	370	(7)
9.5.2 Wave-induced erosion	377	(2)
9.5.3 Erosion by turbidity currents	379	(4)
10. Biological effects	383	(14)
10.1 The role of vegetation	385	(1)
10.2 Bio-deposition	386	(3)
10.3 Bio-stabilisation	389	(4)
10.4 Bio-destabilisation	393	(4)
11. Gas in cohesive sediment	397	(32)
11.1 Introduction	397	(6)
11.2 Gas-related processes in sediment	403	(1)
11.3 Biogenic gas production	404	(3)
11.4 Thermodynamic equilibrium of gas in water	407	(6)
11.4.1 Solubility	407	(3)
11.4.2 Liquid phase	410	(1)
11.4.3 Gas hydrates	410	(3)
11.5 Bubble mechanics	413	(10)
11.5.1 Bubble nucleation	413	(2)
11.5.2 Bubble growth	415	(3)
11.5.3 Ebullition of bubbles	418	(1)
11.5.4 Crack initiation and propagation	419	(4)
11.6 Channel formation	423	(6)
References	429
Appendix A: Nomenclature	A-1
Appendix B: Definitions and useful relations	B-1
Appendix C: Measuring techniques	C-1
C.1 Composition and properties of the sediment-water mixture	C-2
C.2 Particle size distribution	C-6
C.2.1 In-situ particle size distribution in the water column	C-6
C.2.2 In-situ particle size distribution in the bed	C-7
C.2.3 Particle size distribution in the laboratory	C-7
C.2.4 Pore size distribution	C-8
C.3 Sediment concentration and density	C-10
C.3.1 In-situ sediment concentration in the water column	C-10
C.3.2 In-situ sediment-concentration (density) in the bed	C-11
C.3.3 Sediment concentration in the laboratory	C-12
C.4 Rheological parameters	C-14
C.5 Soil mechanical parameters	C-17
C.5.1 Atterberg limits	C-17
C.5.2 Permeability	C-18
C.5.3 Total and pore water pressure	C-19
C.5.4 Consolidation parameters	C-20
C.5.5 Stress-strain relations	C-22
C.6 Settling velocity	C-23
C.6.1 Settling velocity in the laboratory	C-23
C.6.2 In-situ settling velocity	C-24
C.7 Erodibility	C-26
C.7.1 Erosion measurements in the laboratory	C-26
C.7.2 Erosion measurements in the field	C-27
Appendix D: Tensor analysis	D-1
D.1 The stress tensor	D-1
D.2 The strain tensor	D-10
D.3 The strain-rate tensor	D-15
D.4 Momentum and energy equations	D-18
Appendix E: The 1DV POINT MODEL	E-1
E.1 The 1DV-equations	E-1
E.2 Numerical implementation of the 1DV-equations	E-14
E.3 Requirements for numerical accuracy	E-15
Subject index	I-1