566 صفحه
Seafloor Processes and Geotechnoloy, 2016
Ronald C. Chaney
Gideon Almagor
CRC Press
مطالب
Section I Environmental Characterization
1. Origin and Development of Marine Geotechnology ......................................................3
1.1 Introduction ...................................................................................................................3
1.2 Definition and Scope of Marine Geotechnology ......................................................3
1.3 Origin of Marine Geotechnology (1786–1899) ...........................................................4
1.4 Twentieth-Century Precedents (1900–1949)...............................................................5
1.5 Development of Marine Geotechnology (1950–2000) ..............................................5
1.5.1 Two Different Paths .........................................................................................5
1.5.2 Shear Strength Measurements .......................................................................7
1.5.3 Submarine Slope Stability ..............................................................................7
1.5.4 Lake Maracaibo ................................................................................................7
1.5.5 Mississippi Delta ..............................................................................................7
1.5.6 North Sea ..........................................................................................................8
1.5.7 Academic ...........................................................................................................9
1.5.8 Marine Geotechnical Laboratories ................................................................9
1.6 Events Occurring to Change Marine Geotechnology in the Late
1970s and Early 1980s ...................................................................................................9
1.7 Inter- and Multidisciplinary Aspects ....................................................................... 10
2. Geological Environments/Processes and Provinces ..................................................... 15
2.1 Introduction ................................................................................................................. 15
2.2 Plate Tectonics and the Physiography of the Ocean Floor .................................... 16
2.3 Sediment Accumulation and Response to Sea-Level Changes ............................ 18
2.4 Sediments .....................................................................................................................25
2.5 Marine Sedimentary Environments.........................................................................28
2.5.1 Shoreline Depositional System ....................................................................28
2.5.1.1 Siliciclastic Shorelines ....................................................................29
2.5.1.2 Environments of Carbonate and Evaporite Sedimentation .....42
2.5.2 Shallow Open-Sea Environments—Shelf Seas ..........................................49
2.5.2.1 Tide-Dominated Shelves ............................................................... 51
2.5.2.2 Storm-Dominated Shelves ............................................................ 51
2.5.2.3 Oceanic Current-Dominated Shelves .......................................... 52
2.5.3 Continental Slope and Continental Rise .................................................... 52
2.5.3.1 Siliciclastic Slopes and Submarine Fans ..................................... 52
2.5.3.2 Carbonate Slopes ............................................................................ 62
2.5.4 Pelagic Environments .................................................................................... 62
2.5.5 Glaciomarine Depositional Systems ...........................................................65
viii Contents
Section II Site Investigation
3. Elements of Site Investigations .........................................................................................71
3.1 Introduction .................................................................................................................71
3.2 Planning a Site Investigation .....................................................................................71
3.3 Site Survey Flow Plan .................................................................................................75
3.4 Positioning ...................................................................................................................77
3.4.1 Location or Positioning .................................................................................77
3.4.1.1 Above Sea Level ..............................................................................77
3.4.1.2 In Water Column ............................................................................77
3.4.2 Water Depth Determination ......................................................................... 78
3.5 Geophysical Surveys: Equipment and Techniques ................................................79
3.5.1 Introduction ....................................................................................................79
3.5.2 Nature of Underwater Explosions ...............................................................79
3.5.2.1 Introduction ....................................................................................79
3.5.2.2 Nonexplosive Energy Sources ...................................................... 81
3.5.3 Detection of Reflections ................................................................................82
3.5.4 Imaging the Seafloor and Obstacles............................................................83
3.5.5 Vertical Profiling ............................................................................................84
3.5.5.1 Reflection Surveys ..........................................................................84
3.5.5.2 Multichannel Seismic Reflection Profiling .................................85
3.5.5.3 Refraction Surveys .........................................................................85
3.5.6 Interpretation of Records ..............................................................................86
3.5.7 Typical Seismic Profiling Operation ...........................................................86
3.6 Vessel Operations ........................................................................................................87
3.7 In Situ Investigations ..................................................................................................87
3.8 Data Management ....................................................................................................... 87
3.8.1 Types of Data Acquired ................................................................................88
3.8.2 Management of Data (Metadata) .................................................................88
3.8.3 Presentation and Interpretation of Data .....................................................89
3.8.3.1 Presentation of Data .......................................................................89
3.8.3.2 Interpretation of Data ....................................................................90
4. In Situ Testing .......................................................................................................................93
4.1 Introduction .................................................................................................................93
4.2 Deployment Systems ..................................................................................................95
4.2.1 Introduction ....................................................................................................95
4.2.2 Stationary Seabed Systems ...........................................................................95
4.2.2.1 Stingray ............................................................................................97
4.2.2.2 Seacalf ..............................................................................................97
4.2.3 Mobile or Submersible Seabed Systems......................................................98
4.2.4 Borehole Systems ...........................................................................................99
4.2.4.1 Wison Wireline Cone Penetrometer .......................................... 101
4.3 Sensors ........................................................................................................................ 101
4.3.1 Shear Strength .............................................................................................. 101
4.3.1.1 Cone Penetration Test ..................................................................102
Contents ix
4.3.1.2 Mechanical Friction Cone Penetrometer ...................................106
4.3.1.3 Electric Friction Cone Penetrometer ..........................................106
4.3.1.4 Correlations to Physical Properties ........................................... 108
4.3.1.5 Vane Shear Test ............................................................................. 110
4.3.1.6 Correction for Undrained Strength ........................................... 113
4.3.1.7 Determination of Preconsolidation Pressure and OCR ......... 114
4.3.2 Disturbance Caused by In Situ Strength Testing .................................... 116
4.3.2.1 Disturbance Caused by Drilling Operation ............................. 116
4.3.2.2 Disturbance Caused by Probe Insertion ................................... 117
4.3.2.3 Disturbance Caused by Test Procedure .................................... 117
4.3.3 Other Strength Tests .................................................................................... 119
4.3.3.1 Penetrometers ............................................................................... 120
4.3.4 Water Content and Density ........................................................................ 124
4.3.5 Stress–Strain ................................................................................................. 124
4.3.6 Seismic and Shear Wave ............................................................................. 124
4.4 Sensor Calibration ..................................................................................................... 125
4.5 Special-Purpose Tests ............................................................................................... 125
4.5.1 Plate Bearing Tests ....................................................................................... 125
4.5.2 Hydraulic Fracture ....................................................................................... 126
4.5.3 Resistivity/Conductivity ............................................................................. 126
5. Drilling, Sampling, and Handling of Marine Sediments ......................................... 129
5.1 Introduction ............................................................................................................... 129
5.2 Offshore Soil Sampling ............................................................................................ 130
5.2.1 Introduction .................................................................................................. 130
5.2.2 Self-Contained Shallow Penetration Samplers ........................................ 130
5.2.2.1 Gravity Coring Devices ............................................................... 131
5.2.2.2 Bottom Platform ........................................................................... 131
5.2.3 Fixed Seabed Structures ............................................................................. 134
5.2.4 Deep Penetration—Rotary Drilling and Sampling through
a Drill String ................................................................................................. 134
5.2.4.1 Introduction ............................................................................... 134
5.2.4.2 Drill Rig and Other Drilling Components ............................. 136
5.2.4.3 Drill String and Drill Bit .......................................................... 136
5.2.4.4 Vertical Stabilization of the Drill ............................................. 137
5.2.4.5 Samplers Operated in Motion-Uncompensated
Drill String................................................................................. 139
5.3 Sampler Disturbance ................................................................................................ 144
5.3.1 Alterations of Constituent Materials ......................................................... 146
5.4 Handling and Storage .............................................................................................. 154
5.4.1 Handling and Opening of Cores ............................................................... 154
5.4.2 Storage ........................................................................................................... 155
5.4.2.1 Prevention of Moisture Loss ....................................................... 155
5.4.2.2 Vertical versus Horizontal Storage ............................................ 156
5.4.2.3 Storage Time .................................................................................. 156
5.4.2.4 Temperature of Storage ............................................................... 157
x Contents
6. Laboratory Testing at Sea and Ashore............................................................................ 159
6.1 Introduction ............................................................................................................... 159
6.1.1 Requirements for Geotechnical Testing ................................................... 159
6.1.2 Disturbance ................................................................................................... 162
6.1.2.1 Introduction ................................................................................ 162
6.1.2.2 Nature and Mechanism of Sample Disturbance ................... 163
6.1.3 Destructive and Nondestructive Tests ...................................................... 163
6.2 Preparation of Soil Samples ..................................................................................... 165
6.2.1 Introduction .................................................................................................. 165
6.3 Logging, X-Radiography, and Computed Tomography ...................................... 167
6.4 Index/Classification Testing .................................................................................... 167
6.4.1 Introduction .................................................................................................. 167
6.4.2 Principles of Measurement at Sea .............................................................. 168
6.4.2.1 Mass Measurement .................................................................... 168
6.4.2.2 Measurement of Volume Using Helium Pycnometer ........... 168
6.4.2.3 Measurement Matrix for Index Properties ............................. 171
6.4.3 Mass and Volume Relationships ................................................................ 173
6.4.3.1 Water Content ............................................................................. 174
6.4.3.2 Microwave Drying ..................................................................... 176
6.4.3.3 Freeze Drying ............................................................................. 176
6.4.3.4 Pore Water Density..................................................................... 177
6.4.3.5 Bulk Density ................................................................................ 178
6.4.3.6 Density of Solids (Grain Density) ............................................ 179
6.4.3.7 Dry Density/Dry Unit Weight .................................................. 179
6.4.3.8 Porosity ........................................................................................ 180
6.4.3.9 Void Ratio .................................................................................... 181
6.4.3.10 Total Density/Total Unit Weight .............................................. 181
6.4.3.11 Description of Mass–Volume with Correction for Salt
Content in Soils ........................................................................... 182
6.4.4 Particle Characteristics ................................................................................ 189
6.4.4.1 Grain Size Distribution and Classification ............................. 189
6.4.4.2 Mineralogy, Atterberg Limits, and Fabric .............................. 190
6.5 Consolidation ............................................................................................................. 190
6.5.1 Effects of Disturbance ................................................................................. 193
6.5.1.1 Effect on Consolidation Properties .......................................... 194
6.6 Permeability ............................................................................................................... 195
6.6.1 Test Procedures ............................................................................................ 195
6.7 Static Shear Strength ................................................................................................. 196
6.7.1 Undrained Shear Strength .......................................................................... 196
6.7.2 Test Procedure .............................................................................................. 198
6.7.3 Triaxial Testing of High Gas Content Sediments .................................... 199
6.7.3.1 Gas Initially in Solution .............................................................200
6.7.3.2 Gas Initially in Bubble Phase ....................................................203
6.7.3.3 Gas Evolving ...............................................................................204
6.7.3.4 Effect on Strength and Other Properties ................................204
6.7.4 Methods of Correcting Lab Values to In-Situ Strengths ........................205
6.7.4.1 Empirical Correction Method .................................................. 207
6.7.4.2 Analytical Model Technique .................................................... 207
Contents xi
6.7.4.3 Residual Pore Pressure Technique ............................................. 213
6.7.4.4 Analysis of Case Studies ............................................................. 215
6.8 Cyclic and Dynamic Strengths ............................................................................... 216
Section III Geotechnical Properties of Marine Sediments
7. Properties of Marine Soils ................................................................................................ 221
7.1 Introduction ............................................................................................................... 221
7.2 Soil Characterization ................................................................................................ 221
7.2.1 Texture, Structure, and Composition of Soil Particles ........................... 221
7.2.2 Clastic Soils ...................................................................................................222
7.2.2.1 Size, Shape, and Structure ..........................................................222
7.2.2.2 Structure of Coarse-Grained/Noncohesive Sediments ..........225
7.2.2.3 Pore Fluids and Clay Microstructure ........................................227
7.3 Classification of Sediments ......................................................................................233
7.3.1 Laboratory and Visual Procedures ............................................................233
7.3.1.1 Systems of Classification .............................................................233
7.3.1.2 Engineering Classification of Siliciclastic Sediments .............234
7.3.1.3 Classification of Carbonate Sediments ......................................238
7.3.2 In-Situ Classification Methods ................................................................... 243
7.4 Geophysical Properties of Marine Sediments ...................................................... 245
7.4.1 Introduction .................................................................................................. 245
7.4.2 Acoustic Properties of Marine Sediments ................................................ 245
8. Index, Compressibility, and Strength Properties of Marine Sediments ................253
8.1 Introduction ...............................................................................................................253
8.2 Density and Water Content .....................................................................................254
8.3 Consistency Properties and Organic Materials ....................................................256
8.4 Compressibility and Permeability of Fine-Grained Marine Sediments ........... 261
8.4.1 Sedimentation of a Clay–Water System .................................................... 261
8.4.2 Volume Change of Sediments ....................................................................264
8.4.2.1 Modeling Volume Change ..........................................................264
8.4.2.2 Effect of Sediment Deposition and Erosion on
Consolidation ................................................................................ 268
8.4.2.3 Secondary Consolidation ............................................................ 269
8.4.2.4 Apparent Overconsolidation ...................................................... 272
8.5 Permeability ...............................................................................................................277
8.6 Shear Strength Characterization .............................................................................283
8.6.1 Theoretical Background ..............................................................................284
8.6.2 Mohr–Coulomb Approach .........................................................................288
8.6.3 Empirical Approach .................................................................................... 291
8.6.4 Normalized Behavior Approach ............................................................... 291
8.6.5 Typical Shear Strength Behavior ............................................................... 293
8.7 Effect of Time on Soil Behavior ............................................................................... 293
8.7.1 Introduction .................................................................................................. 293
xii Contents
8.7.2 Creep Behavior .........................................................................................295
8.7.2.1 Introduction ............................................................................ 295
8.7.2.2 Viscoelastic Model Approach ..............................................299
8.7.2.3 Rate Process Approach .........................................................300
8.7.2.4 Empirical Approach .............................................................. 301
9. Cyclic and Dynamic Properties of Marine Sediments ...............................................303
9.1 Introduction .............................................................................................................303
9.2 Theoretical Background ........................................................................................303
9.2.1 Threshold Strain Concept .......................................................................305
9.2.2 Clay Minerals under Cyclic Loading ....................................................308
9.2.3 Sands under Cyclic Loading .................................................................. 311
9.3 Soil Parameter Modeling ....................................................................................... 311
9.4 Behavior of Clays and Silts .................................................................................... 314
9.4.1 Strength Determination .......................................................................... 316
9.4.2 Pore Pressure Build-Up ........................................................................... 319
9.4.3 Reduction and Degradation of Stiffness............................................... 322
9.4.3.1 Effect of Soil Plasticity on Cyclic Response ....................... 325
9.4.3.2 Factors That Affect Measurement of Dynamic
Properties of Clays ................................................................. 329
9.5 Analytical Methods to Predict Cyclic Response of Clays ................................. 332
9.6 Behavior of Granular Materials ............................................................................ 332
9.6.1 Mechanism and Implications of Liquefaction Phenomena ...............334
9.6.2 Variations in Liquefaction ......................................................................335
9.6.3 Wave Interaction with Seabed................................................................336
9.6.3.1 Rigid Seabed ........................................................................... 339
9.6.3.2 Deformable Seabed ................................................................340
9.7 Historical Review of Liquefaction in the Coastal Environment ......................342
9.8 Post-Cyclic Loading Behavior ...............................................................................342
Section IV Slope Stability and Foundations
10. Marine Foundations ........................................................................................................... 371
10.1 Introduction ............................................................................................................. 371
10.1.1 Foundation Types .................................................................................... 371
10.2 Loadings on Foundations ...................................................................................... 371
10.3 Pile Structures in the Marine Environment ....................................................... 373
10.3.1 Introduction .............................................................................................. 373
10.3.2 Modeling the Installation and Loading of a Driven Pile ................... 373
10.3.2.1 Capacity of Driven Piles in Clay .......................................... 373
10.3.2.2 Pore Pressure Equalization................................................... 374
10.3.3 Pile Design ................................................................................................ 374
10.3.3.1 Design Loading and Factor of Safety .................................. 374
10.3.3.2 Axial Capacity ........................................................................ 374
10.3.3.3 Pile Settlement ........................................................................ 391
10.3.3.4 Design of Piles for Lateral Loads ......................................... 395
Contents xiii
10.3.3.5 Effect of Cyclic Loading ........................................................ 399
10.3.3.6 Construction and Installation of Pile Structures ..............405
10.4 Gravity Platforms ................................................................................................... 412
10.4.1 Introduction .............................................................................................. 412
10.4.2 Design Requirements .............................................................................. 414
10.4.3 Design Elements ....................................................................................... 415
10.4.4 Geotechnical Design of Foundation System ........................................ 415
10.4.4.1 Bearing Capacity .................................................................... 417
10.4.4.2 Lateral Resistance ..................................................................420
10.4.4.3 Foundation Deformations .................................................... 421
10.4.4.4 Dowel and Skirt Penetration Resistance ............................. 424
10.4.4.5 Base Contact Stress ................................................................427
10.4.4.6 Foundation Tilt .......................................................................427
10.4.4.7 Piping and Erosion ................................................................427
10.4.4.8 Dynamic Analysis .................................................................428
10.4.4.9 Construction and Installation ..............................................428
10.5 Anchor Uplift Capacity ..........................................................................................429
10.5.1 Embedment Mechanisms .......................................................................429
10.5.1.1 Propellant-Actuated Anchor ................................................430
10.5.1.2 Vibration Embedment Anchor .............................................430
10.5.1.3 Screw-In Anchor .................................................................... 431
10.5.1.4 Driven Anchor ........................................................................ 432
10.5.1.5 Jetted Anchors ........................................................................ 432
10.5.2 Anchor Holding Capacity ....................................................................... 432
10.5.2.1 Cohesive Soil: Short-Term Static Loading ...........................434
10.5.2.2 Cohesive Soil: Long-Term Static Loading ...........................435
10.5.2.3 Cohesive Soil: Short-Term Cyclic Loading .........................435
10.5.2.4 Granular Soil: Short- or Long-Term Drained Loading .....435
10.5.2.5 Granular Soil: Long-Term Cyclic Loading ..........................435
10.6 Jack-Up Platforms ...................................................................................................436
10.6.1 Introduction ..............................................................................................436
10.6.2 Support Methods ..................................................................................... 439
10.6.3 Prediction of Leg Penetration during Installation ..............................440
10.6.3.1 Footings Supported on Uniform Soil .................................. 441
10.6.3.2 Footings Supported on Layered Soils ................................. 441
10.7 Hydraulic Filled Islands ........................................................................................447
11. Slope Stability .....................................................................................................................449
11.1 Introduction .............................................................................................................449
11.2 Types of Seafloor Movements ...............................................................................449
11.2.1 Slide Classification ................................................................................... 451
11.2.1.1 Slides Occurring at Time of Deposition ............................. 452
11.2.1.2 Slides Occurring Long after Deposition by Changes
in Sedimentary and Erosional Processes ........................... 452
11.2.1.3 Slides Occurring Long after Deposition due to
Tectonic Processes .................................................................. 452
xiv Contents
11.3 Mechanisms of Movement .................................................................................... 452
11.3.1 Introduction .............................................................................................. 452
11.4 Evaluation of Initiation of Instability ...................................................................453
11.4.1 Introduction ..............................................................................................453
11.4.2 Limit Equilibrium Methods ...................................................................454
11.4.2.1 Undrained Analysis .............................................................. 461
11.4.2.2 Drained Analysis ................................................................... 462
11.4.2.3 Partially Drained Analysis ................................................... 462
11.4.3 Finite-Element Models ............................................................................ 467
11.4.3.1 F.S. Approach .......................................................................... 469
11.4.3.2 Potential Strain Approach .................................................... 469
11.4.3.3 Permanent Deformation Approach ..................................... 470
11.5 Evaluation of the Large Movements of the Soil Mass ....................................... 470
11.5.1 Introduction .............................................................................................. 471
11.5.2 Turbidity Currents (Density Flow Models) .......................................... 472
11.5.3 Plastic and Viscous Flow Models .......................................................... 472
11.5.4 Empirical Methods .................................................................................. 478
11.5.5 Mass Creep ...............................................................................................480
Seafloor Processes and Geotechnology, 2016
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