Aechitectural Graphic Standards Ch 1

Question 1

Clay

Answer 1

determined by the size for particles and composition.

inorganic and have grains less than 0.0002” in diameter.

charged particles and affinity for water.

cohesion and plasticity.

stiff, medium, or soft.

satisfactory bearing material.

Question 2

Silt

Answer 2

inorganic particles less than 0.003” and 0.0002” in diameter.

found at bottom of lakes and river deltas.

Question 3

Sand

Answer 3

0.003” - 0.079” in diameter.

compacted = ideal bearing material

coarse and fine.

Question 4

Gravel

Answer 4

fine to coarse. 0.003” - 0.079” in diameter. fragments range from 0.75” ~ 3”.

good foundation material

Question 5

Cobbles

Answer 5

3”-10”.

reliable foundation-bearing, difficult to compact when used for fill.

Question 6

Boulders

Answer 6

rock fragments greater than 10”.

fill mass of voids between boulders are filled with finer-grained sands and silts.

not good for direct foundation support.

Question 7

Bedrock

Answer 7

Unbroken hard rock.

desirable for extremely high bearing pressure and loads.

Question 8

Residuum

Answer 8

soils derived from the in-place decomposition of bedrock materials.

more weathered near the surface and rocklike with depth.

Question 9

Alluvial Soils

Answer 9

loose and saturated. not good for support of structures or pavements.

Question 10

Colluvial Soils

Answer 10

irregular and loose in composition. Improvement required prior to being used to support buildings or pavements.

Question 11

Aeolian Soils

Answer 11

silt or sand-sized soils. Component in place but loses strength when disturbed or recompacted.

Question 12

Till

Answer 12

Mixture of clay, silt, sand, gravel, and boulders deposited by glaciers.

well graded = excellent foundation strata

Question 13

Loam

Answer 13

humus and sand, silt, or clay

agriculture not foundations

Question 14

Cohesionless Soils

Answer 14

cobbles, gravels, sands, and nonplastic silts.

formed by mechanical weathering

strength caused by interparticle friction

Question 15

Cohesive Soils

Answer 15

clay minerals with unbalanced chemical charge.

attracts water = bonds

Question 16

Consolidation

Answer 16

soils subjected to loads, water within the void spaces supports the change in stress through an increase in pressure.

the resulting reduction in volume over time = consolidation

Question 17

Underconsolidated Soils

Answer 17

Soils deposited in a very loose state. Never experienced stresses equal to or greater than current overburden stresses.

Foundations can expect large short- and long-term settlement.

Question 18

Overconsolidated Soils

Answer 18

Not elastic. Soils that have previously been loaded to stresses above those created by the current soil overburden.

Foundations can expect less short- and long-term settlements.

Question 19

Desiccation

Answer 19

When soils are dried, capillary tension pulls the soil grains together = soils shrinks and lose volume.