Soils Exam 3 Davids Comeback

Preconsolidation Pressure is the maximum effective vertical overburden stress a soil sample has sustained in the past. This quantity is important for understanding soil, particularly for calculating the expected settlement of foundations and embankments. True or False?

True

When all conditions are the same, you expect more settlement from the over-consolidated soil layers than from the normally consolidated soil layers. True or False?

False

According to the Elastic theory method, which calculates the stress (pressure) increment in the subsurface soil layer, the stress (pressure) in the subsurface layers increases by the same magnitude regardless of the location of the contract area. True or False?

False

effective stress is total stress minus pore water pressure. True or False?

True

Which of the following soils has the lowest permeability? Gravel, Sand, Silt, or Clay.

Clay

Which of the following soils has the highest permeability? dirty sand, Clean sand, Clean and Coarse Gravel, Silty clay.

Clean and Coarse Gravel

Which of the following construction applications needs high-permeable soil?

Irrigation Dike/Canal Wall

Septic pipe backfill in the discharge field

Earthen Dam core

Bottom of pond

Septic pipe backfill in the discharge field

The coefficients of permeability for vertical and horizontal flow through non-homogeneous soil layers are always the same. True or False?

False

The approximate method is based on the assumption that the subsurface stress below increases with depth. True or False?

False

Stresses exist at a point within a soil mass due to the _______ of soil laying above that point and as a result of _____ superimposed on the soil mass. Choose the right combination of correct answers.

Soil weight and loads

weight and compaction

water volume or pore water stresses

Air Volume and loads

Soil Weight and Loads

Total stress is the sum of effective stress and neutral stress (pore water pressure). True or False?

True

Effective stress does not include pore water pressure. True or False?

True

According to Elastic Theory applying uniform load over a rectangular area, the vertical stress at depth z below each corner of the rectangle is consistent regardless of depth and dimensional sizes. True or False?

False

Applying the Elastic Theory method to calculate subsurface stress increment at the center of a uniform rectangular area, how many division(s) of the rectangular area is(are) required?

one

two

three

four

Four

Compression causes settlement of soils during or after construction.

Two compression mechanisms are 1) consolidation and 2) compaction.

Consolidation is removing water, and compaction is removing air voids between soil particles. True or False?

True

Consolidation occurs in ________ soil layer, causing settlement over the long period.

Gravel and Sand mix

Gravel, and silt mix

Saturated clay

50% Silt and 50% Sand Mix

Saturated clay

When the load P is applied to the saturated clay soil (subject to consolidation), it is initially applied to porewater stress and then carried by the soil solids as effective stress.

Correct

Incorrect

completely out of sense statement

no answer text provided

Correct

The field consolidation line is constructed from an e-log p graph based on the lab consolidation tests. The field consolidation line is used to calculate the magnitude of the settlement using changes in void ratios by increasing pressure ratings.

Correct

incorrect

Field consolidation line is not used for settlement calculations

Correct

When the applied load is less than pre-consolidated pressure, over-consolidated soils are expected to yield less settlement than normally consolidated soils.

Over conolidation is not related to the magnitude of settlement

Yes

No

Normally consolidated soil has less settlement

Yes

Under the same loading condition, double vertical drainage settles much faster than single drainage.

False, single is faster

True, double is faster

Drainage condition doesnt matter because permeiability coefficient is no different

no difference

True, Double s faster

According to the Elastic theory method that calculates the stress (pressure) increment in the subsurface soil layer, the stress (pressure) at the subsurface layers increases equally at the center and edges of the structure on the ground. True or False?

False

What soil has the Highest Permiability?

Gravel

Consolidation mainly occurs in which type of soil?

Fine graded soils

Highest capilary rise?

Clay

why does water flow in soils change direction and flow rates?

It is due to the fact that soils are layered

What type of drainage is better?

shorter or longer?

Shorter

How does stress incrament and surface loading work?

It decreases by depth but as the depth goes deeper, the area gets larger. (Underground pyramid)

What is the difference between compaction and consolidation?

Compaction: when the void is being compressed out of the soil

Consolidation: When water is squeezed out of the soil

True consolidation needs many tests. True or False?

True

What is the definition of pre-consolidation?

The maximum affective vertical overburden stress that a particular soil sample has sustained in the past. Important for finding expected settlement.

What is the definition of primary settlement?

When water is squeezed out over long period of time

What is the deffinition of secondary settlment?

when the soil particles are being compressed

Is over consolidation good, bad, or doesnt matter?

Good news