Term
| name the 4 classifications of soils |
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Definition
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Term
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Definition
| SG = (density of substance) / (density of water) |
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Term
| What is "effective stress" in soil bearing? |
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Definition
| effective stress = (total stress) - (pore water pressure, "u") |
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Term
| What is the pore water pressure, "u", above and below the water table? |
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Definition
| above the water table, it is equal to zero. below the water table, it increases linearly with depth (i.e. a typical fluid). |
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Term
| describe standard penetration test (SPT) and blow count. |
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Definition
| a standard split-spoon sampler is driven by a hammer dropped from a standard height. the blow count, "N", is the number of blows required to travel 12 inches. |
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Term
| describe cone penetrometer test |
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Definition
| It's an alternative to the standard penetration test (SPT). a pointed cone is pushed through soil at a continous rate, and resistance is measured at the tip and sides of the cone. downside: no boring sample is collected, so borings need to be done in addition. disadvantages: cone is expensive and can be damaged/stuck in stiff soils. |
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Term
| Proctor Test measures _____ _________ |
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Definition
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Term
| how does the geotech / civil engineer specify soil compaction? |
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Definition
| specs call for the minimum acceptable density (a percentage of the maximum density determined from the Proctor test) and range of acceptable water content |
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Term
| what is the difference between the Proctor Test and the Modified Proctor Test? |
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Definition
| Proctor Test is 3 layers of soil with a 5.5 lb. hammer dropped 12". Modified Proctor Test is 5 layers of soil, with a 10 lb. hammer falling 18in. |
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Term
| soil angle of internal friction |
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Definition
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Term
| For footing design, how do you account for overburden stress? |
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Definition
| Allowable bearing capacity (aka NET allowable) is the allowed pressure in excess of the overburden stress. |
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