Front Cover
 Title Page
 Table of Contents
 List of Figures
 List of Tables
 List of symbols
 Study background and methodolo...
 Preliminary experiments
 Estimations of fluid mud thickness...
 Mud bed fluidization experimen...
 Experimental data analysis

Group Title: UFL/COEL (University of Florida. Coastal and Oceanographic Engineering Laboratory) ; 92/005
Title: Laboratory experiments on cohesive soil bed fluidization by water waves
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00080460/00001
 Material Information
Title: Laboratory experiments on cohesive soil bed fluidization by water waves
Series Title: UFLCOEL
Physical Description: xvi, 109 leaves : ill., photos ; 28 cm.
Language: English
Creator: Feng, Jingzhi ( Dissertant )
Mehta, Ashish J. ( Thesis advisor )
Dean, Robert G. ( Reviewer )
Moudgil, Brij M. ( Reviewer )
McVay, Michael C. ( Reviewer )
University of Florida -- Coastal and Oceanographic Engineering Dept
Publisher: Coastal & Oceanographic Engineering Dept., University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 1992
Copyright Date: 1992
Subjects / Keywords: Coastal and Oceanographic Engineering thesis M.S   ( local )
Dissertations, Academic -- UF -- Coastal and Oceanographic Engineering   ( local )
Abstract: The mechanism by which fluid mud is formed by water wave motion over coastal and estuarine cohesive soil beds is of evident interest in understanding and interpreting the microfabric of flow-deposited fine sediments in shallow waters, and hence the erodibility of muddy beds due to hydrodynamic forcing. This study investigated water wave-induced fluidization of cohesive soil beds composed of a 50/50 (by weight) mixture of a commercial attapulgite and a kaolinite in a laboratory flume. Temporal and spatial changes of the effective stress were measured during the course of wave action, and from these changes the bed fluidization rate was calculated. A previously developed hydrodynamic wave-mud interaction model of the two-layered water-mud system was employed to study the nature and the degree of wave dissipation, in terms of energy dissipation rate, during the bed fluidization process. By evaluating the mud rheological properties separately, a mud viscosity model was developed, which was then used in conjunction with the wave-mud interaction model to obtain an effective sheared thickness of the bed resulting from wave action. This thickness, considered to be a representative of the fluidized mud thickness, was compared with the latter obtained from pressure measurements. Also, through this wave-mud model the relationship between the rate of fluidization and the rate of wave energy dissipation during fluidization was examined. In general, for a given wave frequency, a larger wave fluidized the bed at a faster rate and to a greater depth than a smaller one. Furthermore, increased bed consolidation time decreased the rate of fluidization due to increased mud rigidity. The rate of bed fluidization was typically greater at the beginning of wave action and decreased with time. Eventually this rate approached zero, while in some cases the wave energy dissipation rate approached a constant value, which increased with wave height. As the fluidization rate approached zero, there appeared to occur an equilibrium value of the bed elevation, and hence a fluid mud thickness, for a given wave condition. During the fluidization process the bed apparently lost its structural integrity by loss of the effective stress through a build-up of the excess pore water pressure. After wave action ceased, the bed structure exhibited recovery by dissipation of the excess pore water pressure. Further studies will be required in which the hydrodynamic model must be improved via a more realistic description of mud rheology and relaxation of the shallow water assumption, and better pressure data must be obtained than in the present study. Nevertheless, this investigation has been instructive in demonstrating relationships between the degree of mud fluidization, wave energy dissipation and bed consolidation time, and thus offers insight into an important mechanism by which coastal and estuarine muds are eroded by wave action. xvi
Abstract: ocean waves, fluidization, rheology
Thesis: Thesis, M.S., Engineering
Funding: This publication is being made available as part of the report series written by the faculty, staff, and students of the Coastal and Oceanographic Program of the Department of Civil and Coastal Engineering.
 Record Information
Bibliographic ID: UF00080460
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.


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Table of Contents
    Front Cover
        Front Cover
    Title Page
        Page i
        Page ii
    Table of Contents
        Page ii
        Page iii
    List of Figures
        Page iv
        Page v
        Page vi
    List of Tables
        Page viii
        Page ix
    List of symbols
        Page x
        Page xi
        Page xii
        Page xiii
        Page xiv
        Page xvi
        Page 1
        Page 2
        Page 3
        Page 4
    Study background and methodology
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
    Preliminary experiments
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
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        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
    Estimations of fluid mud thickness and wave energy dissipation
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
    Mud bed fluidization experiments
        Page 61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
        Page 72
        Page 73
        Page 74
        Page 75
    Experimental data analysis
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
        Page 81
        Page 82
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