Term
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Definition
| All the loose material lying above bedrock |
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Term
| Are all soil definitions the same? |
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Definition
| The term "soil" does not have the same definitions and constraints for soil scientists, geologists, and engineers |
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Term
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Definition
| Most interested in soil organic and hydrologic properties to examine the ability to SUPPORT PLANT LIFE |
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Term
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Definition
| Classify based on engineering purposes (e.g., shear strength) |
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Term
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Definition
| Distinguish between residual soils and transported soils; interested in origin, transport and deposition. |
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Term
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Definition
| Includes humus (organic matter) holds moisture and prevents erosion. |
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Term
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Definition
| Small rock material, high concentrations of clay and oxide minerals |
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Term
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Definition
| Big rocks, small rocks + juvenile soils -> where the above soil came from |
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Term
| Soil types: Geologists perspective |
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Definition
Most soils are residual soils, that is they evolve in place from bedrock to regolith to well-developed soil horizons.
Soils that accumulate in low areas after being eroded are called transported soils. |
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Term
| Soil classification: Engineers |
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Definition
Soils for engineering purposes are based on:
-texture/particle size: gravel, sand, silt, clay
-particle size distribution: into well-graded and poorly-graded soils
-density: closely related to its compressibility, or tendency to settle and compact under an applied load
-shear strength: determines the ability of the soil to support the load of a structure or remain stable on a hillslope
** many of these factors are influenced by the water content of the soil |
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Term
| What are some soil hazards? |
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Definition
Soil material is commonly undergoing a change of volume due to loss or gain of water, exposure to stress or vibrations
-expansive soils
-hydrocompaction of soils
-collapsing soils
-soil liquefaction
- subsidence |
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Term
| What are some effect of weathering and soil hazards on building materials and soils? |
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Definition
-decrease in strength
-loss of elasticity
-decrease in density
-increase in volume
-increase in moisture content
-increase in porosity |
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Term
| What is the most costly source of damage to structures in North America? |
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Definition
expansive soils
-these soils contain a high proportion of swelling clays (clay minerals tend to draw water molecules into the spaces between the silicate sheets, which causes the mineral to swell) |
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Term
| Why do some clays show expansive behaviour? |
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Definition
| Clays have high porosity! |
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Term
| What kinds of damage is caused by expansive soils? |
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Definition
-roller coaster roads
-differential expansion of soils can lead to structural damage
-cracks in houses |
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Term
| What is goal of preloading soils? |
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Definition
To reduce post construction settlement and improve load bearing capacity.
Soils treated: organic silt, varved silts and clays, soft clay, dredged material
Disadvantage: can lead to significant delay of construction projects = $$$$ !!! |
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Term
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Definition
| Refers to the tendency for loose uncompacted soils that are found in some arid environments to compact under load when they are wetted |
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Term
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Definition
| Is defined as a weakly cemented soil subject to large settlement under load and as a result of deterioration of the cementing agent in presence of water. |
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Term
| What is weathering by solution/carbonation and karst formation? |
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Definition
Carbonate rocks dissolved in acidic to neutral waters (surficial or underground)
Problems: sinkholes, foundation for dams, extreme cases - dam failure. |
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Term
| Chemical weathering by hydration and tunnel construction |
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Definition
-Tunnels often pass through dry materials
-tunneling process exposes rock material to atm
-water uptake can lead to swelling of rock |
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Term
| Mining Practices -> Case Studies |
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Definition
-mining processes lead to the exposure and increased surface area of material that has been buried deeply for millions of years or has never seen the surface before
-these materials may unstable under atmospheric
conditions
-depending on the composition these materials may be "extremely prone to weathering" and lead to hazardous acid mine drainage |
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