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A poorly-graded soil is a soil that does not have a good representation of all sizes of particles from the no. 4 to no. 200 sieve. A poorly-graded gravel is classified as GP, while a poorly-graded sand is classified as SP. Poorly-graded soils are more susceptible to soil liquefaction than well-graded soils. [1]
gravel > 50% of coarse fraction retained on No.4 (4.75 mm) sieve clean gravel <5% smaller than No.200 Sieve GW well-graded gravel, fine to coarse gravel GP poorly graded gravel gravel with >12% fines GM silty gravel GC clayey gravel sand ≥ 50% of coarse fraction passes No.4 (4.75 mm) sieve clean sand SW well-graded sand, fine to coarse sand SP
If the soil particles in a sample are predominantly in a relatively narrow range of sizes, the sample is uniformly graded. If a soil sample has distinct gaps in the gradation curve, e.g., a mixture of gravel and fine sand, with no coarse sand, the sample may be gap graded. Uniformly graded and gap graded soils are both considered to be poorly ...
A sieve analysis (or gradation test) is a practice or procedure used in geology, civil engineering, [1] and chemical engineering [2] to assess the particle size distribution (also called gradation) of a granular material by allowing the material to pass through a series of sieves of progressively smaller mesh size and weighing the amount of material that is stopped by each sieve as a fraction ...
The activity of soil is the ratio of the plasticity index to the clay size fraction. If activity is less than 0.75, the soil is inactive. If activity exceeds 1.4, then the soil is termed active. If activity lies within the above values, then the soil will be moderately active. [10]
CBR values for common soil subgrades can be estimated according to the USC soil types, for example: clay around 2%, sand from 7% (poorly graded) to 10% (well graded), well graded sandy gravel 15%, clayey sand 5-20%, silty gravel 20-60%, gravel from 30-60% poorly-graded to 40-80% if well-graded. [6] [7]
The first modern theoretical models for soil consolidation were proposed in the 1920s by Terzaghi and Fillunger, according to two substantially different approaches. [1] The former was based on diffusion equations in eulerian notation, whereas the latter considered the local Newton’s law for both liquid and solid phases, in which main variables, such as partial pressure, porosity, local ...
The energy exerted by compaction forces the soil to fill available voids, and the additional frictional forces between the soil particles improves the mechanical properties of the soil. Because a wide range of particles are needed in order to fill all available voids, well-graded soils tend to compact better than poorly graded soils.