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33 Cards in this Set
- Front
- Back
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Shallow foundation |
soil is tender |
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Deep foundation |
for high building or heavy loads |
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Geotechnical earthquake engineering |
Huge shock absorbers, walls that slide and Teflon foundation pads that isolate buildings from the gorund all help explain why medium -- and high-rise structures in Japan remained standing in the wake of the country's largest earthquake on record |
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Geoenvironmental |
Landfill design, site assessment, contaminant transport, and site remediation |
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Natural hazards |
Flood protection systems, mudslides, and geotechnical earthquake engineering |
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Emerging geotechnical challenges |
Kart sinkholes, sinkhole by internal erosion, CO2 geostorage, and gas hydrate bearing sediment |
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Soil characteristics |
- soil is particulate media (not continuum) - soil is 3-phase media (solid, water, and gas) - soil is most often used in its natural state and not manufactured - soil is heterogeneous and anisotropic in its natural state in the field - soil is spatially variable on both large and small scales - soil is relatively weak and compressible compared to steel and concrete |
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Geotechnical engineering |
- application of soil mechanics, rock mechanics, geology/geological engineering, engineering judgement/economics - very limited use of code-based design procedures - blend of "science" (theoretically based methods) and "art" (empirically based methods) |
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Scale of analysis |
1. Geological ~100 m 2. Geotechnical engineering ~10 m 3. Lab ~10 cm 4. Microscopic ~ 1 micrometer |
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Rock classes |
1. Igneous 2. Sedimentary 3. Metamorphic |
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Igneous |
results form cooling of magma |
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Sedimentary |
- results from residual or transported deposits of either igneous or metamorphic rock - formed by accumulated deposits of soil particles or remains of organisms that are hardened by pressure and cemented by minerals |
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Metamorphic |
results from igneous or sedimentary rock undergoing change by heat and/or pressure, generally to a harder, stronger state |
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Types of igneous rocks |
1. Basalt - magma cooled quickly 2. Granite - magma cooled slowly (larger crystals) |
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Types of sedimentary rocks |
1. Sandstone - from deposited sands 2. Shale - deposited clay 3. Limestone - deposited skeletal fragments of marine organism |
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Types of metamorphic rocks |
1. Gneiss - from sedimentary rocks, basalt or granite 2. Marble - from limestone 3. Quartzite - from sandstone |
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Types of weathering |
1. Mechanical weathering 2. Chemical weathering |
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Mechanical weathering |
transformation via mechanical means including: - moving water (i.e. erosion) - glacial movement - thermal expansion and contraction - plant roots - wave action - wind - freezing and thawing of water in cracks and joints |
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Chemical weathering |
Transformation via chemical reactions including: - oxidation - hydration - reduction - carbonation - solution - hydrolysis - leaching - cation exchange |
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Quartz (mineral) effect on weathering |
Inert to chemical weathering and reasonably resistant to mechanical weathering |
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Feldspars (mineral) effect on weathering |
Very susceptible to chemical weathering |
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Micas (mineral) effect on weathering |
Similar to feldspars but more resistant to chemical weathering |
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Transported soils |
1. Colluvium 2. Alluvium 3. Lacustrine or marine 4. Loess 5. Aeolian 6. Glacial till |
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Colluvium |
gravity (e.g. landslide) |
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Alluvium |
running water (e.g. river) |
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Lacustrine or marine |
still water (e.g. lake or ocean) |
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Loess |
wind-blown, uniform, fine-grained soil |
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Aeolian |
sand-sized particles deposited by wind |
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Glacial till |
glacial movement |
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Post-depositional processes |
1. Aging 2. Cementation 3. Dissolution 4. Various diageneses |
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Residual soils (vs transported soils) |
- soils that remain at the site of weathering - retains many of the elements that comprise the parent rock |
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Two main techniques to determine Grain Size Distribution (GSD) |
1. Coarse-grained soils: gravel and sand (>= 0.075 mm), sieve analysis (ASTM D422)
The soil is passed through a series of standard test sieves having successively smaller mesh sizes. The mass of soil retained in each sieve is determined and the cumulative percentage by mass passing each sieve is calculated. 2. Fine-grained soils: silt and clay (<= 0.075 mm), hydrometer analysis Sieves cannot be used for fine-grained soils because of their extremely small size. The particle size distribution of a fine soil size can be determined by the method of sedimentation. This method is based on Stoke's law, which governs the velocity at which spherical particles settle in a suspension: the larger the particles the greater the setting velocity. |
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Stages of soil |
brittle-solid, semi-solid, plastic, liquid |
