Soils 2 Flashcards
(32 cards)
Which stress in the ground is typically largest?
Vertical
What is an inherent property of pore water pressure?
It is isotropic
Where is pore pressure usually referenced from?
0 at the top of the water table
What do all measurable effects of a change in stress depend on?
Effective Stress
What caries effective stress?
Grain to grain contacts
That governs soil behavior?
Effective Stress
What is a typical value of the coefficient of lateral earth pressure for sands?
0.3 to 0.8
What is a typical value of the coefficient of lateral earth pressure for clays?
0.5 to»_space; 2
What is coefficient of lateral earth pressure sensitive to?
stress history
What does the total stress depend only upon?
The weight of the soil and water able it.
When is soil stability lost?
when effective stress is 0.
What is the value of i cr for most soils?
0.9 to 1.1 with an average of 1.
Where does heaving generally occur with respect to sheet piles?
within a distance D/2
For an ideal capillary tube, what does alpha equal.
alpha equals 0.
Soil Compression
A stress increase caused by the construction of foundation or other loads, compresses the soil. Deformation of soil particles, Reorientation of soil particles, Expulsion of water or air from the void space.
Elastic Settlement
Caused by the elastic deformation of dry soil and of moist and saturated soils without any change in the moisture content.
Consolidation Settlement
which is the result of volume change in saturated cohesive soil because of expulsion of water that occupies the void spaces.
What happens to saturated sandy soil when consolidation occurs?
Pore water pressure increases immediately, drainage caused by pore water pressure is immediate, elastic settlement and consolidation simultaneously occur
What happens to saturated clayey soils when consolidation occurs.
Pore water pressure increases immediately. Drainage caused by increased pore water pressure occurs slowly and gradually. Associated settlement (consolidation) in the clay continues long time after elastic settlement. Settlement caused by consolidation is usually several times greater then elastic settlement.
Normally Consolidated
the present effective overburden pressure is the maximum pressure to which the soil has been ever subjected in the history.
Overconsolidated
the present effective overburden pressure is less than that which the soil has experienced in the pas
Preconsolidated pressure
The maximum effective past pressure for an over consolidated soil
Compression Index Cc
the slope of the virgin consolidation curve
Swell Index Cs
is the slope of the recompression curve
