Soil Mechanics, Materials, & Testing Flashcards

1
Q

What is a quick clay?

A
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2
Q

What is a dispersive soil?

A

Highly erodible clays that often appear as “normal clear”
Difficult to identify from visual inspection/common index tests

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3
Q

What is a collapsible soil?

A

Fine sand and silt with loose structure and weak inter-particle bonds.
Potential for collapse and highly erodible

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4
Q

What soil types does immediate (also known as elastic) settlement occur in?

A

All Types

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5
Q

When does immediate/elastic settlement occur?

A

During and right after construction

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6
Q

What is the dominant settlement in cohesionless, granular, coarse-grained soils?

A

Immediate/Elastic

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7
Q

What is another term for immediate settlement?

A

Elastic settlement

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8
Q

What is the dominant settlement in clay?

A

Primary consolidation

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9
Q

Why does primary consolidation occur in clays?

A

Due to the slow drainage of porewater with excess pressure due to loading

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10
Q

What causes secondary settlement

A

Particle rearrangement and creep

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11
Q

Primary consolidation takes a ____ time and is _____

A

long, substantial

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12
Q

Normally Consolidated (NC) Clay

A

The current effective overburden pressure is equal to the max pressure the soil has been subjected to in the recent past.

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13
Q

Overconsolidated (OC) Clay

A

The current effective overburden pressure is less than the max pressure the soil has been subjected to in the recent past.

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14
Q

Water has a _____ effect on the internal friction angle of cohesionless (gravels, sands) soils. However, the effective stress ______ which causes a _______ overall shear resistance.

A

negligible, decreases, lower

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15
Q

An increased water content of clay results in ______ shear strength and _____ cohesion.

A

decreased, decreases

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16
Q

How do you determine D60, D10, etc.

A

It is the average grain size for the amount passing the X%. Need the chart.

17
Q

Liquid Limit

A

Moisture content at which the soil goes from a plastic state to a liquid state.

18
Q

Plastic Limit

A

Moisture content at which the soil goes from a semisolid to a plastic state.

19
Q

A higher PI indicates a higher ________ and _________.

A

clay particle content and chance of problems (swell potential and heave)

20
Q

Liquidity Index (LI)

A

Relates the moisture content of soil to PI

21
Q

Tensile Stress

A

When a material stretches or increases in length from the addition of a force.

22
Q

Compressive Stress

A

When a material shortens or decreases in length from the addition of a force.

23
Q

Shear Stress

A

Force at which sections or layers move in opposite directions.

24
Q

Define a Poorly Graded Soil

A

Uneven distribution of soil sizes

25
Q

Define a Well Graded Soil

A

Even distribution of soil sizes

26
Q

Define a Gap Graded Soil